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Showing new listings for Thursday, 21 November 2024
- [1] arXiv:2411.12751 [pdf, other]
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Title: Flexible and Generic Framework for Complex Nuclear Medicine Scanners using FreeCAD/GDML WorkbenchSubjects: Medical Physics (physics.med-ph)
The design of nuclear imaging scanners is crucial for optimizing detection and imaging processes. While advancements have been made in simplistic, symmetrical modalities, current research is progressing towards more intricate structures, however, the widespread adoption of computer-aided design (CAD) tools for modeling and simulation is still limited. This paper introduces FreeCAD and the GDML Workbench as essential tools for designing and testing complex geometries in nuclear imaging modalities. FreeCAD is a parametric 3D CAD modeler, and GDML is an XML-based language for describing complex geometries in simulations. Their integration streamlines the design and simulation of nuclear medicine scanners, including PET and SPECT scanners. The paper demonstrates their application in creating calibration phantoms and conducting simulations with Geant4, showcasing their precision and versatility in generating sophisticated components for nuclear imaging. The integration of these tools is expected to streamline design processes, enhance efficiency, and facilitate widespread application in the nuclear imaging field.
- [2] arXiv:2411.12810 [pdf, html, other]
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Title: The d-electron contribution to the stopping power of transition metalsComments: 13 figures. Manuscript submitted to Physical Review A, under evaluationSubjects: Atomic Physics (physics.atom-ph); Materials Science (cond-mat.mtrl-sci)
We present a new non-perturbative model to describe the stopping power by ionization of the $d$-electrons of transition metals. These metals are characterized by the filling of the d-subshell and the promotion of part of the electrons to the conduction band. The contribution of d-electrons at low-impact energies has been noted experimentally in the past as a break of the linear dependence of the stopping power with the ion velocity. In this contribution, we describe the response of these electrons considering the atomic "inhomogeneous" momentum distribution. We focus on the transition metals of Groups 10 and 11 in the periodic table: Ni, Pd, Pt, Cu, Ag, and Au. Results describe the low energy-stopping power, with good agreement with the experimental data and available TDDFT results. By combining the present non-perturbative model for the $d$-subshell contribution with other approaches for the valence electrons and for the inner shells, we provide a coherent theoretical method capable of describing the stopping power of these transition metals from the very low to the high energy region.
- [3] arXiv:2411.12821 [pdf, html, other]
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Title: Coherent Structures in One-dimensional Buneman Instability Nonlinear SimulationsSubjects: Plasma Physics (physics.plasm-ph)
Long-duration one-dimensional PIC simulations are presented of Buneman-unstable, initially Maxwellian, electron and ion distributions shifted with respect to one another, providing detailed phase-space videos of the time-dependence. The final state of high initial ion temperature cases is dominated by fast electron holes, but when initial ion temperature is less than approximately four times the electron temperature, ion density modulation produces potential perturbations of approximately ion-acoustic character, modified by the electron distribution shift. Early in the nonlinear phase, they often have electron holes trapped in them ("coupled hole-solitons": CHS). In high-available-energy cases, when major broadening of the electron distribution occurs, both electron holes and coupled hole-solitons can be reflected, giving persistent counter-propagating potential peaks. Analytical theory is presented of steady nonlinear potential structures in model nonlinear particle distribution plasmas with Buneman unstable parameters. It compares favorably in some respects with the nonlinear simulations, but not with the later phases when the electron velocity distributions are greatly modified.
- [4] arXiv:2411.12823 [pdf, other]
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Title: Evaluation of Analytical Models in Scattering Scanning Near-field Optical Microscopy for High Spatial Resolution SpectroscopyJournal-ref: The 29th Iranian Conference on Optics and Photonics (ICOP 2023)Subjects: Optics (physics.optics)
Scattering scanning near-field optical microscopy (s-SNOM) is a technique to enhance the spatial resolution, and when combined by Fourier transform spectroscopy it can provide spectroscopic information with high spatial resolution. This paper studies two analytical models for the s-SNOM probe using atomic force microscopy (AFM) tip and its interaction with a dielectric material. We evaluate the validity of these models by retrieving the permittivity spectrum of a sample material through an inverse method.
- [5] arXiv:2411.12855 [pdf, html, other]
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Title: Linking emitted drops to collective bursting bubbles across a wide range of bubble size distributionsComments: 29 pages, 9 figuresSubjects: Fluid Dynamics (physics.flu-dyn)
Bubbles entrained by breaking waves rise to the ocean surface, where they cluster before bursting and release droplets into the atmosphere. The ejected drops and dry aerosol particles, left behind after the liquid drop evaporates, affect the radiative balance of the atmosphere and can act as cloud condensation nuclei. The remaining uncertainties surrounding the sea spray emissions function motivate controlled laboratory experiments that directly measure and link collective bursting bubbles and the associated drops and sea salt aerosols. We perform experiments in artificial seawater for a wide range of bubble size distributions, measuring both bulk and surface bubble distributions (measured radii from 30 um to 5 mm), together with the associated drop size distribution (salt aerosols and drops of measured radii from 50 nm to 500 um) to quantify the link between emitted drops and bursting surface bubbles. We evaluate how well the individual bubble bursting scaling laws describe our data across all scales and demonstrate that the measured drop production by collective bubble bursting can be represented by a single framework integrating individual bubble bursting scaling laws over the various bubble sizes present in our experiments. We show that film drop production by bubbles between 100 um and 1 mm describes the submicron drop production, while jet drop production by bubbles from 30 um to 2 mm describes the production of drops larger than 1 um. Our work confirms that sea spray emissions functions based on individual bursting processes are reasonably accurate as long as the surface bursting bubble size distribution is known.
- [6] arXiv:2411.12862 [pdf, html, other]
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Title: Non-unique water and contrast agent solutions in dual-energy CTComments: Proceedings paper for accepted contribution to the 8th International Conference on Image Formation in X-Ray Computed TomographySubjects: Medical Physics (physics.med-ph)
The goal of this work is to study occurrences of non-unique solutions in dual-energy CT (DECT) for objects containing water and a contrast agent. Previous studies of the Jacobian of nonlinear systems identified that a vanishing Jacobian determinant indicates the existence of multiple solutions to the system. Vanishing Jacobian determinants are identified for DECT setups by simulating intensity data for practical thickness ranges of water and contrast agent. Once existence is identified, non-unique solutions are found by simulating scan data and finding intensity contours with that intersect multiple times. With this process non-unique solutions are found for DECT setups scanning iodine and gadolinium, including setups using tube potentials in practical ranges. Non-unique solutions demonstrate a large range of differences and can result in significant discrepancies between recovered and true material mapping.
- [7] arXiv:2411.12883 [pdf, html, other]
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Title: Single Mode Wave DecayComments: Submitted for publication in Physics of PlasmasSubjects: Plasma Physics (physics.plasm-ph)
The usual approach on electrostatic wave decay process for a weak beam-plasma system considers two different wave modes interplaying, the Langmuir and ion-sound mode. In the present paper, a single mode approach is shown to be feasible for conditions where the respective dispersion relations undergo topological changes. Numerical solutions for the dispersion relation of a beam-plasma system are presented, supporting the modeling of an analytic dispersion relation of a single wave mode. This wave mode is accounted for in the kinetic equations for particles and waves, which rule the evolution of the system. The results are compared against the two-wave mode approach using Langmuir and ion-sound waves, within the context of weak turbulence theory. It is found that the single mode approach can account for the basic features of particles and waves, since the single mode exhibits both a region of low and high frequency which ultimately play the roles of ion-sound and Langmuir modes, respectively.
- [8] arXiv:2411.12885 [pdf, html, other]
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Title: Time-resolved Coulomb explosion imaging of vibrational wave packets in alkali dimers on helium nanodropletsNicolaj K. Jyde, Henrik H. Kristensen, Lorenz Kranabetter, Jeppe K. Christensen, Emil Hansen, Mads B. Carlsen, Henrik StapelfeldtSubjects: Atomic and Molecular Clusters (physics.atm-clus)
Vibrational wave packets are created in the lowest triplet state \triplet of $\mathrm{K_2}$ and $\mathrm{Rb_2}$ residing on the surface of helium nanodroplets, through non-resonant stimulated impulsive Raman scattering induced by a moderately intense near-infrared laser pulse. A delayed, intense 50-fs laser pulse doubly ionizes the alkali dimers via multiphoton absorption and thereby causes them to Coulomb explode into a pair of alkali ions $\mathrm{Ak^+}$. From the kinetic energy distribution $P(E_\mathrm{kin})$ of the $\mathrm{Ak^+}$ fragment ions, measured at a large number of delays, we determine the time-dependent internuclear distribution $P(R,t)$, which represents the modulus square of the wave packet within the accuracy of the experiment. For both $\mathrm{K_2}$ and $\mathrm{Rb_2}$, $P(R,t)$ exhibits a periodic oscillatory structure throughout the respective 300 ps and 100 ps observation times. The oscillatory structure is reflected in the time-dependent mean value of $R$, $\langle R \rangle(t)$. Fourier transformation of $\langle R \rangle(t)$ shows that the wave packets are composed mainly of the vibrational ground state and the first excited vibrational state, in agreement with numerical simulations. In the case of $\mathrm{K_2}$, the oscillations are observed for 300 ps corresponding to more than 180 vibrational periods with an amplitude that decreases gradually from 0.035 Å to 0.020 Å. Using time-resolved spectral analysis, we find that the decay time of the amplitude is $\sim$ 260 ps. The decrease is ascribed to the weak coupling between the vibrating dimers and the droplet.
- [9] arXiv:2411.12905 [pdf, other]
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Title: Nonlinear optics in 2D materials: from classical to quantumSubjects: Optics (physics.optics); Materials Science (cond-mat.mtrl-sci)
Nonlinear optics has long been a cornerstone of modern photonic technology, enabling a wide array of applications, from frequency conversion to the generation of ultrafast light pulses. Recent breakthroughs in two-dimensional (2D) materials have opened a frontier in this field, offering new opportunities for both classical and quantum nonlinear optics. These atomically thin materials exhibit strong light-matter interactions and large nonlinear responses, thanks to their tunable lattice symmetries, strong resonance effects, and highly engineerable band structures. In this paper, we explore the potential that 2D materials bring to nonlinear optics, covering topics from classical nonlinear optics to nonlinearities at the few-photon level. We delve into how these materials enable possibilities, such as symmetry control, phase matching, and integration into photonic circuits. The fusion of 2D materials with nonlinear optics provides insights into the fundamental behaviors of elementary excitations such as electrons, excitons, and photons in low dimensional systems and has the potential to transform the landscape of next-generation photonic and quantum technologies.
- [10] arXiv:2411.12926 [pdf, html, other]
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Title: Characterization of sea ice kinematics over oceanic eddiesSubjects: Fluid Dynamics (physics.flu-dyn)
Eddies within the meso/submeso-scale range are prevalent throughout the Arctic Ocean, playing a pivotal role in regulating freshwater budget, heat transfer, and sea ice transport. While observations have suggested a strong connection between the dynamics of sea ice and the underlying turbulent flows, quantifying this relationship remains an ambitious task due to the challenges of acquiring concurrent sea ice and ocean measurements. Recently, an innovative study using a unique algorithm to track sea ice floes showed that ice floes can be used as vorticity meters of the ocean. Here, we present a numerical and analytical evaluation of this result by estimating the kinematic link between free-drifting ice floes and underlying ocean eddies using idealized vortex models. These analyses are expanded to explore local eddies in quasi-geostrophic turbulence, providing a more realistic representation of eddies in the Arctic Ocean. We find that in both flow fields, the relationship between floe rotation rates and ocean vorticity depends on the relative size of the ice floe to the eddy. As the floe size approaches and exceeds the eddy size, the floe rotation rates depart from half of the ocean vorticity. Finally, the effects of ice floe thickness, atmospheric winds, and floe-floe collisions on floe rotations are investigated. The derived relations and floe statistics set the foundation for leveraging remote sensing observations of floe motions to characterize eddy vorticity at small to moderate scales. This innovative approach opens new possibilities for quantifying Arctic Ocean eddy characteristics, providing valuable inputs for more accurate climate projections.
- [11] arXiv:2411.12933 [pdf, html, other]
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Title: Degradation of performance in ICF implosions due to Rayleigh--Taylor instabilities: a Hamiltonian perspectiveComments: 24 pages, 10 figures, accepted in Phys. PlasmasSubjects: Plasma Physics (physics.plasm-ph); Fluid Dynamics (physics.flu-dyn)
The Rayleigh--Taylor instability (RTI) is an ubiquitous phenomenon that occurs in inertial-confinement-fusion (ICF) implosions and is recognized as an important limiting factor of ICF performance. To analytically understand the RTI dynamics and its impact on ICF capsule implosions, we develop a first-principle variational theory that describes an imploding spherical shell undergoing RTI. The model is based on a thin-shell approximation and includes the dynamical coupling between the imploding spherical shell and an adiabatically compressed fluid within its interior. Using a quasilinear analysis, we study the degradation trends of key ICF performance metrics (e.g., stagnation pressure, residual kinetic energy, and aerial density) as functions of initial RTI parameters (e.g., the initial amplitude and Legendre mode), as well as the 1D implosion characteristics (e.g., the convergence ratio). We compare analytical results from the theory against nonlinear results obtained by numerically integrating the governing equations of this reduced model. Our findings emphasize the need to incorporate polar flows in the calculation of residual kinetic energy and demonstrate that higher convergence ratios in ICF implosions lead to significantly greater degradation of key performance metrics.
- [12] arXiv:2411.12937 [pdf, html, other]
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Title: Demonstration of OpenMC as a framework for atomic transport and plasma interactionComments: 17 pages, 9 figuresSubjects: Plasma Physics (physics.plasm-ph); Computational Physics (physics.comp-ph)
Modern tooling is demanded for predicting the transport and reaction characteristics of atoms and molecules, especially in the context of magnetic confinement fusion. DEGAS2, among the most common and capable tools currently in use, shares many fundamental similarities with the OpenMC framework, which was primarily developed for neutron and photon transport. In this work, we demonstrate that OpenMC is suitable for atomic transport calculations. The relative error between the models is small, and the performance of OpenMC is at least comparable to DEGAS2. This is the case even without taking advantage of heterogeneous computing architecture, which is only one of the several remarkable new capabilities that this demonstration heralds.
- [13] arXiv:2411.12966 [pdf, html, other]
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Title: Internal stresses in low-Reynolds-number fractal aggregatesSubjects: Fluid Dynamics (physics.flu-dyn)
We present a numerical model of fractal-structured aggregates in low-Reynolds-number flows. Assuming that aggregates are made of cubic particles, we first use a boundary integral method to compute the stresses acting on the boundary of the aggregates. From these external stresses, we compute the stresses within the aggregates in order to gain insights on their breakup, or disaggregation. We focus on systems in which aggregates are either settling under gravity or subjected to a background shear flow and study two types of aggregates, one with fractal dimension slightly less than two and one with fractal dimension slightly above two. We partition the aggregates into multiple shells based on the distance between the individual cubes in the aggregates and their center of mass and observe the distribution of internal stresses in each shell. Our findings indicate that large stresses are least likely to occur near the far edges of the aggregates. We also find that, for settling aggregates, the maximum internal stress scales as about 7.5% of the ratio of an aggregate's apparent weight to the area of the thinnest connection, here a single square. For aggregates exposed to a shear flow, we find that the maximum internal stress scales roughly quadratically with the aggregate radius. In addition, after breaking aggregates at the face with the maximum internal stress, we compute the mass distribution of sub-aggregates and observe significant differences between the settling and shear setups for the two types of aggregates, with the low-fractal-dimension aggregates being more likely to split approximately evenly. Information obtained by our numerical model can be used to develop more refined dynamical models that incorporate disaggregation.
- [14] arXiv:2411.12988 [pdf, html, other]
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Title: Angle measurement method of electronic speckle interferometry based on Michelson interferometerSubjects: Applied Physics (physics.app-ph); Instrumentation and Detectors (physics.ins-det)
{This paper proposes an angle measurement method based on Electronic Speckle Pattern Interferometry (ESPI) using a Michelson interferometer. By leveraging different principles within the same device, this method achieves complementary advantages across various angle ranges, enhancing measurement accuracy while maintaining high robustness. By utilizing CCD to record light field information in real time and combining geometric and ESPI methods, relationships between small angles and light field information are established, allowing for the design of relevant algorithms for real-time angle measurement. Numerical simulations and experiments were conducted to validate the feasibility and practicality of this method. Results indicate that it maintains measurement accuracy while offering a wide angle measurement range, effectively addressing the limitations of small angle measurements in larger ranges, showcasing significant potential for widespread applications in related fields.
- [15] arXiv:2411.13002 [pdf, html, other]
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Title: Multi-scale simulation of red blood cell trauma in large-scale high-shear flows after Norwood operationComments: 31 pages, 16 figuresSubjects: Fluid Dynamics (physics.flu-dyn)
Cardiovascular surgeries and mechanical circulatory support devices create non-physiological blood flow conditions that can be detrimental, especially for pediatric patients. A source of complications is mechanical red blood cell (RBC) damage induced by the localized supraphysiological shear fields. To understand such complications, we introduce a multi-scale numerical model to predict the risk of hemolysis in a set of idealized anatomies. We employed our in-house CFD solver coupled with Lagrangian tracking and cell-resolved fluid-structure interaction to measure flow-induced stresses and strains on the RBC membrane. The Norwood procedure, well-known to be associated with high mortality rate, is selected for its importance in the survival of the single-ventricle population. We simulated three anatomies including 2.5mm and 4.0mm diameter modified Blalock-Taussig (BT) shunts and a 2.5mm central shunt (CS), with hundreds of RBCs in each case for statistical analysis. The results show that the conditions created by these surgeries can elongate RBCs by more than two-fold (3.1% of RBCs for 2.5mm BT shunt, 1.4% for 4mm BT shunt, and 8.8% for CS). Shear and areal strain metrics also reveal that the central shunt creates the greatest deformations on the RBCs membrane, indicating it is a more hemolytic procedure in comparison to the BT shunt. Between the two BT shunts, the smaller diameter is slightly more prone to hemolysis. These conclusions are confirmed when strain history and different damage thresholds are considered. The spatial damage maps produced based on these metrics highlighted hot zones that match the clinical images of shunt thrombosis.
- [16] arXiv:2411.13013 [pdf, html, other]
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Title: Revisiting the hyperfine interval for the $2s2p$ $^3\!P_{J}$ state in $^9$BeSubjects: Atomic Physics (physics.atom-ph)
Using relativistic multiconfiguration Dirac-Hartree-Fock method, we calculate the hyperfine-structure properties of the $2s2p$ $^3\!P_{J}$ state in $^9$Be. The hyperfine-structure properties encompass first-order hyperfine-structure parameters, as well as second-order and third-order corrections arising from the hyperfine mixing of different $2s2p$ $^3\!P_{J}$ levels. Based on our theoretical results, we reanalyze the previously reported measurement of the hyperfine interval for the $2s2p$ $^3\!P$ state in $^9$Be [A. G. Blachman and A. Lurio, Phys. Rev. 153, 164(1967)], yielding updated hyperfine-structure constants. Our results show that the hyperfine-structure constant $B$ of $2s2p$ $^3\!P_{1}$ is notably sensitive to second-order correction. Conversely, accurately determining the hyperfine-structure constant $B$ of $2s2p$ $^3\!P_{2}$ necessitates consideration of the hyperfine-structure constant $C$ in the first-order hyperfine interaction equation. The updated hyperfine-structure constant $B$ of the $2s2p$ $^3\!P_{2}$ state is found to be $1.4542(67)$~MHz, which is approximately $1.7\%$ larger than the previous value of $1.427(9)$~MHz.
By combining our theoretical results with the updated hyperfine-structure constant for the $2s2p$ $^3\!P_{2}$ state, we extract the electric quadrupole moment $Q$ of $^9$Be nucleus to be $0.05320(50)$~b. This value is consistent with the most recent determination using the few-body precision calculation method. Additional, we also discuss the reasons for the discrepancy between the $Q$ values obtained through few-body and previous many-body calculations. - [17] arXiv:2411.13035 [pdf, other]
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Title: Study of Group III-V Waveguides on Sapphire Platform for Photonic Integrated CircuitsManoj Kumar Shah, Richard A. Soref, Diandian Zhang, Wei Du, Gregory J. Salamo, Shui-Qing Yu, Mansour MortazaviComments: 15 pages, 5 figuresSubjects: Optics (physics.optics); Applied Physics (physics.app-ph)
Photonic integrated circuits (PICs) have been acknowledged as the promising platforms for the applications in data communication, Lidar in autonomous driving vehicles, innovative sensor technology, etc. Since the demonstration of optical components individually, integration of both electronics and photonics for functional devices on a common platform has been a key technology driver enhancing the stability and scalability of integrated photonic technologies. Recently, we proposed to use sapphire as a high-performance PIC platform, which enables a fully integrated solution to include a complete set of components with light source, modulator, light detection, passive devices, silicon on sapphire control circuit all-in-one sapphire platform to achieve high-performance low-cost mixed-signal optical links. In parallel to developing ac-tive components such as group III-V lasers on sapphire, in this work, the performance of group III-V straight waveguides on sapphire was systemically studied. The refractive indices contrast between GaAs, InP, GaSb, and sapphire are sufficiently high to achieve low loss over a broad optical wavelength. The calculated loss at wavelengths of 1330 nm, 1550 nm, and 2000 nm for the GaAs, InP, and GaSb rib waveguides are 0.32 dB/cm, 0.67 dB/cm, and 0.70 dB/cm, re-spectively. Since the fundamental element to construct all passive building blocks is the straight waveguide, results from this work would allow us to assess other basic passive building blocks.
- [18] arXiv:2411.13046 [pdf, html, other]
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Title: Active Stabilization of Laser Diode Injection Using a Polarization-Spectroscopy TechniqueSubjects: Optics (physics.optics); Atomic Physics (physics.atom-ph); Quantum Physics (quant-ph)
Laser diode injection-locking is a commonly used method to amplify laser light, while preserving its spectral properties. Fluctuations in the environmental conditions can cause injection-locking to fail, especially when operating with low seed powers or with a swept seed frequency. We present a method inspired by the Hänsch-Couillaud scheme to monitor and actively stabilize the conditions required for injection-locking a laser diode. Using only a few optical components, our scheme can run continuously in the background and is modulation-free. We demonstrate its efficacy by showing its robustness to large fluctuations in diode temperature, seed frequency and power, effectively extending the reliable operating range and stability over time.
- [19] arXiv:2411.13064 [pdf, html, other]
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Title: Twisted fibre: a photonic topological insulatorComments: 23 pages, 16 figuresSubjects: Optics (physics.optics)
The breaking and enforcing of symmetries is a crucial ingredient in designing topologically robust materials. While magnetic fields can break time-reversal symmetry to create Chern insulators in electronic and microwave systems, at optical frequencies natural materials cannot respond to magnetic fields, which presents a challenge for the scalable exploitation of topologically enhanced devices. Here, we leverage the natural geometry of fibre to build a scalable photonic Chern insulator by twisting the fibre during fabrication. The twist inside optical fibre breaks an effective time-reversal symmetry and induces a pseudo-magnetic field, which we observe via photonic Landau levels. Unavoidably, this twist introduces a competing topology-destroying effect through a parabolic profile in the effective refractive index. Using simulations to guide experimental materials design, we discover the Goldilocks regime where the real-space Chern invariant survives, guaranteeing topological protection against fabrication-induced disorder of any symmetry class.
- [20] arXiv:2411.13077 [pdf, html, other]
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Title: Far-field Boundary Conditions for Airfoil Simulation at High Incidence in Steady, Incompressible, Two-dimensional FlowComments: 32 pages, 14 figuresSubjects: Fluid Dynamics (physics.flu-dyn)
This study concerns the far-field boundary conditions (BCs) for airfoil simulations at high incidence where the lift and drag are comparable in magnitude and the moment is significant. A NACA 0012 airfoil was simulated at high Reynolds number with the Spalart-Allmaras turbulence model in incompressible, steady flow. We use the impulse form of the lift, drag, and moment equations applied to a control volume coincident with the square computational domain, to explore the BCs. It is well known that consistency with the lift requires representing the airfoil by a point vortex, but it is largely unknown that consistency with the drag requires a point source as was first discovered by Lagally (1922) and Filon (1926). We show that having a point source in the BCs is more important at high drag than using a point vortex. The reason is that BCs without a point source cause blockage at the top and bottom sidewalls in a manner very similar to wind tunnel blockage for experiments. A simple "Lagally-Filon" correction for small levels of blockage is derived and shown to bring the results much closer to those obtained using boundary conditions including a point source. Although consistent with the lift and drag, the combined point vortex and source boundary condition is not consistent with the moment equation but the further correction for this inconsistency is shown to be very small. We speculate that the correction may be more important in cases where the moment is critical, such as vertical-axis turbines.
- [21] arXiv:2411.13092 [pdf, other]
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Title: On Macroscopic Intricate StatesFrançois Dubois (LMSSC)Journal-ref: Kybernetes, 2017, 47 (2), pp.321-332Subjects: Biological Physics (physics.bio-ph)
The present contribution is in the field of quantum modelling of macroscopic phenomena. The focus is on one enigmatic aspect of quantum physics, namely the Einstein-Podolsky-Rosen paradox and entanglement. After a review of the state of the art concerning macroscopic quantum effects and quantum interaction, this contribution proposes a link between embryology and acupuncture in the framework of macroscopic intricate states induced by quantum mechanics.
- [22] arXiv:2411.13098 [pdf, html, other]
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Title: Method for overcoming the finite space-bandwidth limitation of digital holograms in holographyComments: 9 pages, 6 figuresSubjects: Optics (physics.optics)
A digital hologram has a finite space-bandwidth, which determines the spatial resolution and angular field of view of its reconstructed image. However, a higher space-bandwidth induces aliased replica patterns in the Fresnel diffraction. This study analyzes the spatial distribution of the angular spectrum in an undersampled hologram within the complex domain. The replica functions are identified as higher spatial frequency components of the original function, with the spatial frequency range extending continuously from the original function into the region of the replica functions. Simulations of optical imaging show results consistent with theoretical analysis, demonstrating that imaging performance beyond the space-bandwidth limitation of a digital hologram is achievable. Specifically, a method is proposed to address the challenge of limited viewing angles in holographic displays based on this interpretation. This approach provides an alternative solution to overcome the constraints imposed by the finite space-bandwidth of digital holograms.
- [23] arXiv:2411.13115 [pdf, html, other]
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Title: How interfacial tension enhances drag in turbulent Taylor-Couette flow with neutrally buoyant and equally viscous dropletsSubjects: Fluid Dynamics (physics.flu-dyn)
The presence of dispersed-phase droplets can result in a notable increase in the system's drag. However, our understanding of the mechanism underlying this phenomenon remains limited. In this study, we use three-dimensional direct numerical simulations with a modified multi-marker volume-of-fluid method to investigate liquid-liquid two-phase turbulence in a Taylor-Couette geometry. The dispersed phase has the same density and viscosity as the continuous phase. The Reynolds number $Re\equiv r_i\omega_i d/\nu$ is fixed at 5200, the volume fraction of the dispersed phase is up to $40\%$, and the Weber number $We\equiv \rho u^2_\tau d/\sigma$ is around 8. It is found that the increase in the system's drag originates from the contribution of interfacial tension. Specifically, droplets experience significant deformation and stretching in the streamwise direction due to shear near the inner cylinder. Consequently, the rear end of the droplets lags behind the fore head. This causes opposing interfacial tension effects on the fore head and rear end of the droplets. For the fore head of the droplets, the effect of interfacial tension appears to act against the flow direction. For the rear end, the effect appears to act in the flow direction. The increase in the system's drag is primarily attributed to the effect of interfacial tension on the fore head of the droplets which leads to the hindering effect of the droplets on the surrounding continuous phase. This hindering effect disrupts the formation of high-speed streaks, favoring the formation of low-speed ones, which are generally associated with higher viscous stress and drag of the system. This study provides new insights into the mechanism of drag enhancement reported in our previous experiments.
- [24] arXiv:2411.13128 [pdf, html, other]
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Title: Third-order Orbital Corner State and its Realization in Acoustic CrystalsComments: 10 pages, 7 figuresSubjects: Applied Physics (physics.app-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Three dimensional (3D) third-order topological insulators (TIs) have zero-dimensional (0D) corner states, which are three dimensions lower than bulk. Here we investigate the third-order TIs on breathing pyrochlore lattices with p-orbital freedom. The tight-binding Hamiltonian is derived for the p-orbital model, in which we find that the two orthogonal ${\pi}$-type (transverse) hoppings are the key to open a band gap and obtain higher-order topological corner states. We introduce the Z4 berry phase to characterize the bulk topology and analysis the phase diagram. The corner states, demonstrated in a finite structure of a regular tetrahedron, exhibit rich 3D orbital configurations. Furthermore, we design an acoustic system to introduce the necessary ${\pi}$-type hopping and successfully observe the orbital corner states. Our work extends topological orbital corner states to third-order, which enriches the contents of orbital physics and may lead to applications in novel topological acoustic devices.
- [25] arXiv:2411.13167 [pdf, html, other]
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Title: Anomalous propagators and the particle-particle channel: Bethe-Salpeter equationComments: 19 pages, 8 figuresSubjects: Chemical Physics (physics.chem-ph); Materials Science (cond-mat.mtrl-sci); Mathematical Physics (math-ph); Nuclear Theory (nucl-th)
The Bethe-Salpeter equation has been extensively employed to compute the two-body electron-hole propagator and its poles which correspond to the neutral excitation energies of the system. Through a different time-ordering, the two-body Green's function can also describe the propagation of two electrons or two holes. The corresponding poles are the double ionization potentials and double electron affinities of the system. In this work, a Bethe-Salpeter equation for the two-body particle-particle propagator is derived within the linear-response formalism using a pairing field and anomalous propagators. This framework allows us to compute kernels corresponding to different self-energy approximations ($GW$, $T$-matrix, and second-Born) as in the usual electron-hole case. The performance of these various kernels is gauged for singlet and triplet valence double ionization potentials using a set of 23 small molecules. The description of double core hole states is also analyzed.
- [26] arXiv:2411.13168 [pdf, html, other]
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Title: Entropy-stable fluxes for high-order Discontinuous Galerkin simulations of high-enthalpy flowsSubjects: Fluid Dynamics (physics.flu-dyn)
In the present work, we extend the Discontinuous Galerkin Spectral Element Method (DGSEM) to high-enthalpy reacting gas flows with internal degrees of freedom. An entropy- and kinetic energy-preserving flux function is proposed which allows for use of arbitrary expressions for the internal energies of the constituent gas species. The developed method is applied to simulation of several model problems and compared to the DLR TAU solver.
- [27] arXiv:2411.13174 [pdf, other]
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Title: Production and Loss Processes of Hydrogen Energetic Neutral Atoms in the Heliosphere from 5 eV to 500 keVComments: 22 pages, 7 figures, 3 tables, submitted to ApJSSubjects: Space Physics (physics.space-ph); Solar and Stellar Astrophysics (astro-ph.SR); Atomic Physics (physics.atom-ph)
Energetic Neutral Atom (ENA) observations provide valuable insights into the plasma conditions in the heliosphere and the surrounding interstellar medium. Unlike plasma detectors, which measure charged particles tied to the magnetic fields at their location, ENA detectors capture former ions that were neutralized in distant regions and traverse the heliosphere in straight trajectories. ENA fluxes near the Sun represent line-of-sight integrals of parent ion fluxes multiplied by neutralization (production) rates and reduced by the probability of ENA reionization (loss) processes. So far, most ENA analyses have focused on charge exchange between hydrogen atoms and protons as the primary source of ENAs. Here, we examine various ENA production and loss processes throughout the heliosphere in the broad energy range (5 eV to 500 keV) encompassing the next-generation ENA instruments aboard the Interstellar Mapping and Acceleration Probe (IMAP) mission. Our study considers binary collisions involving the most abundant species: protons, electrons, {\alpha}-particles, He+ ions, photons, as well as hydrogen and helium atoms. Our findings indicate that, in addition to ENAs produced by charge exchange of energetic protons with hydrogen atoms, a significant portion of high-energy ENAs originate from the charge exchange with helium atoms. Below 10 keV, the dominant ENA loss processes are charge exchange collisions with protons and photoionization. However, stripping ionization processes, e.g., from collisions with ambient interstellar neutral hydrogen, become the main loss mechanism for higher energies because the charge exchange rate rapidly decreases.
- [28] arXiv:2411.13185 [pdf, html, other]
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Title: Recovering Mullins damage hyperelastic behaviour with physics augmented neural networksJournal-ref: Journal of the Mechanics and Physics of Solids, Vol. 193, 2024Subjects: Computational Physics (physics.comp-ph)
The aim of this work is to develop a neural network for modelling incompressible hyperelastic behaviour with isotropic damage, the so-called Mullins effect. This is obtained through the use of feed-forward neural networks with special attention to the architecture of the network in order to fulfil several physical restrictions such as objectivity, polyconvexity, non-negativity, material symmetry and thermodynamic consistency. The result is a compact neural network with few parameters that is able to reconstruct the hyperelastic behaviour with Mullinstype damage. The network is trained with artificially generated plane stress data and even correctly captures the full 3D behaviour with much more complex loading conditions. The energy and stress responses are correctly captured, as well as the evolution of the damage. The resulting neural network can be seamlessly implemented in widely used simulation software. Implementation details are provided and all numerical examples are performed in Abaqus.
- [29] arXiv:2411.13194 [pdf, html, other]
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Title: Solver-in-the-loop approach to turbulence closureSubjects: Fluid Dynamics (physics.flu-dyn); Chaotic Dynamics (nlin.CD)
We present a novel methodology for modeling the influence of the unresolved scales of turbulence for sub-grid modeling. Our approach employs the differentiable physics paradigm in deep learning, allowing a neural network to interact with the differential equation evolution and performing an a posteriori optimization by incorporating the solver into the training iteration (an approach known as solver-in-the-loop), thus departing from the conventional a priori instantaneous training approach. Our method ensures that the model is exposed to equations-informed input distributions, accounting for prior corrections and often leading to more accurate and stable time evolution. We present results of our methodology applied to a shell model of turbulence, and we discuss further potential applications to Navier-Stokes equations.
- [30] arXiv:2411.13195 [pdf, other]
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Title: A Systematic Review of Empirical Research on Graphing Numerical Data in K-12 STEM EducationVerena Ruf, Dominik Thues, Sarah Malone, Stefan Kuechemann, Sebastian Becker-Genschow, Markus Vogel, Roland Bruenken, Jochen KuhnComments: 63 pages, 9 figuresSubjects: Physics Education (physics.ed-ph)
Graphs are essential representations in the professions and education concerning the science, technology, engineering, and mathematics (STEM) disciplines. Beyond their academic relevance, graphs find extensive utility in everyday scenarios, ranging from news media to educational materials. This underscores the importance of people's being able to understand graphs. However, the ability to understand graphs is connected to the ability to create graphs. Therefore, in school education, particularly in STEM subjects, not only the understanding but also the skill of constructing graphs from numerical data is emphasized. Although constructing graphs is a skill that most people do not require in their everyday lives and professions, it is a well-established student activity that has been empirically studied several times. Therefore, since a synthesis of the research findings on this topic has not yet been conducted, a summary of the studies investigating graphing via various viewpoints and differing methods could be a valuable contribution. To provide an overview of the empirical literature on this important topic, our systematic review identifies how the construction of convention-based graphical representations of numerical data, referred to as graphing, has been studied in previous research, how effective graphing is, and which types of difficulties are encountered by students. Based on these aspects, we defined inclusion criteria that led to 50 peer-reviewed empirical studies on graphing in K-12 STEM education found in SCOPUS, ERIC, and PsychInfo. Graphing instruction seemed to be beneficial for student learning, not only improving graph construction but also graph interpretation skills. However, the students experienced various difficulties during graphing, both during graph construction and the interpretation and usage of data.
- [31] arXiv:2411.13196 [pdf, html, other]
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Title: Salts promote or inhibit bubbly drag reduction in turbulent Taylor-Couette flowsSubjects: Fluid Dynamics (physics.flu-dyn)
Bubbly drag reduction is considered as one of the most promising techniques to reduce the energy consumption of marine vessels. With this technique bubbles are injected under the hull where they then lubricate the hull, thus reducing the drag of the vessel. Understanding the effects of salts on bubbly drag reduction is therefore of crucial importance in the application of this technique for salt waters. In this study we investigate the effects of MgCl2, Na2SO4, substitute sea salt, and NaCH3COO on the reduction of drag by bubbles in turbulent Taylor-Couette flow. We find that MgCl2, Na2SO4, and substitute sea salt inhibit bubble coalescence, leading to smaller bubbles in the flow, which prove to be less effective for bubbly drag reduction. For these salts we find that the ionic strength is a decent indicator for the observed drag reduction and solutions of these salts with an ionic strength higher than I >= 0.7 mol/l show little to no drag reduction. In contrast, NaCH3COO solutions do not inhibit bubble coalescence and for this salt we even observe an enhanced drag reduction with increasing salt concentration. Finally, for all cases we connect the observed drag reduction to the bubble Weber number and show that bubble deformability is of utmost importance for effective bubbly drag reduction.
- [32] arXiv:2411.13221 [pdf, other]
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Title: Observation of non-Hermitian boundary induced hybrid skin-topological effect excited by synthetic complex frequenciesTianshu Jiang, Chenyu Zhang, Ruo-Yang Zhang, Yingjuan Yu, Zhenfu Guan, Zeyong Wei, Zhanshan Wang, Xinbin Cheng, C. T. ChanSubjects: Optics (physics.optics); Materials Science (cond-mat.mtrl-sci)
The hybrid skin-topological effect (HSTE) has recently been proposed as a mechanism where topological edge states collapse into corner states under the influence of the non-Hermitian skin effect (NHSE). However, directly observing this effect is challenging due to the complex frequencies of eigenmodes. In this study, we experimentally observe HSTE corner states using synthetic complex frequency excitations in a transmission line network. We demonstrate that HSTE induces asymmetric transmission along a specific direction within the topological band gap. Besides HSTE, we identify corner states originating from non-chiral edge states, which are caused by the unbalanced effective onsite energy shifts at the boundaries of the network. Furthermore, our results suggest that whether the bulk interior is Hermitian or non-Hermitian is not a key factor for HSTE. Instead, the HSTE states can be realized and relocated simply by adjusting the non-Hermitian distribution at the boundaries. Our research has deepened the understanding of a range of issues regarding HSTE, paving the way for advancements in the design of non-Hermitian topological devices.
- [33] arXiv:2411.13253 [pdf, html, other]
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Title: The vDZP Basis Set Is Effective For Many Density FunctionalsComments: 14 pages, 1 figureSubjects: Chemical Physics (physics.chem-ph)
In recent years, "composite" density-functional-theory-based methods comprising specially optimized combinations of functionals, basis sets, and empirical corrections have become widely used owing to their robustness and computational efficiency, but the bespoke nature of these methods makes them challenging to develop. Here, we report that the recently reported vDZP basis set can be used in combination with a wide variety of density functionals to produce efficient and accurate results comparable to those obtained with composite methods, but without any method- or correction-specific reparameterization. This result enables rapid quantum chemical calculations to be run with a variety of density functionals without the typical errors incurred by small basis sets.
- [34] arXiv:2411.13256 [pdf, html, other]
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Title: Prevention of resistive wall tearing mode major disruptions with feedbackSubjects: Plasma Physics (physics.plasm-ph)
Resistive wall tearing modes (RWTM) can cause major disruptions. A signature of RWTMs is that the rational surface is sufficiently close to the wall. For $(m,n) = (2,1)$ modes, at normalized minor radius $\rho = 0.75$, the value of $q$ is $q_{75} < 2.$ This is confirmed in simulations and theory and in a DIII-D locked mode disruption database. The $q_{75} < 2$ criterion is valid at high $\beta$ as well as at low $\beta.$ A very important feature of RWTMs is that they produce major disruptions only when the $q_{75} < 2$ criterion is satisfied. If it is not satisfied, or if the wall is ideally conducting, then the mode does not produce a major disruption, although it can produce a minor disruption. Feedback, or rotation of the mode at the wall by complex feedback, can emulate an ideal wall, preventing major disruptions. The $q_{75}$ criterion is analyzed in a linear simulations, and a simple geometric model is given.
- [35] arXiv:2411.13265 [pdf, html, other]
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Title: Edge-Detected 4DSTEM -- effective low-dose diffraction data acquisition method for nanopowder samples in a SEM instrumentComments: 16 pages, 9 figuresSubjects: Applied Physics (physics.app-ph)
The appearance of direct electron detectors marked a new era for electron diffraction. Their high sensitivity and low noise opens the possibility to extend electron diffraction from transmission electron microscopes (TEM) to lower energies such as those found in commercial scanning electron microscopes (SEM).The lower acceleration voltage does however put constraints on the maximum sample thickness and it is a-priori unclear how useful such a diffraction setup could be. On the other hand, nanoparticles are increasingly appearing in consumer products and could form an attractive class of naturally thin samples to investigate with this this http URL this work we present such a diffraction setup and discuss methods to effectively collect and process diffraction data from dispersed crystalline nanoparticles in a commercial SEM instrument. We discuss ways to drastically reduce acquisition time while at the same time lowering beam damage and contamination issues as well as providing significant data reduction leading to fast processing and modest data storage needs. These approaches are also amenable to TEM and could be especially useful in the case of beam-sensitive objects.
- [36] arXiv:2411.13268 [pdf, html, other]
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Title: Enhanced Gas Source Localization Using Distributed IoT Sensors and Bayesian InferenceLeonardo Balocchi, Lorenzo Piro, Luca Biferale, Stefania Bonafoni, Massimo Cencini, Iacopo Nannipieri, Andrea Ria, Luca RoselliSubjects: Fluid Dynamics (physics.flu-dyn)
Identifying a gas source in turbulent environments presents a significant challenge for critical applications such as environmental monitoring and emergency response. This issue is addressed through an approach that combines distributed IoT smart sensors with an algorithm based on Bayesian inference and Monte Carlo sampling techniques. Employing a probabilistic model of the environment, such an algorithm interprets the gas readings obtained from an array of static sensors to estimate the location of the source. The performance of our methodology is evaluated by its ability to estimate the source's location within a given time frame. To test the robustness and practical applications of the methods under real-world conditions, we deployed an advanced distributed sensors network to gather water vapor data from a controlled source. The proposed methodology performs well when using both the synthetic data generated by the model of the environment and those measured in the real experiment, with the source localization error consistently lower than the distance between one sensor and the next in the array.
- [37] arXiv:2411.13275 [pdf, html, other]
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Title: Extreme firebrand transport by atmospheric waves in wildfiresSubjects: Fluid Dynamics (physics.flu-dyn); Dynamical Systems (math.DS); Geophysics (physics.geo-ph)
In wildfires, burning pieces of ember-firebrands-are carried downstream by wind. At the time of landing, these firebrands can start secondary fires far away from the main burning unit. This phenomenon is called spotting and the secondary fires are referred to as spot fires. Here, we first present numerical evidence that atmospheric traveling waves can increase the spotting distance by at least an order of magnitude compared to unidirectional wind conditions. We then present theoretical results explaining this numerical observation. In particular, we show that the firebrand's motion can synchronize with the traveling wave, leading to a surf-like motion for some firebrand particles. This delays the firebrand's landing, making extreme spotting distances possible. This physical phenomena helps explain the discrepancy between previous theoretical estimates of maximum spotting distance and much larger spotting distances observed empirically. We derive new analytical expressions for the landing time and landing distance of the firebrands.
- [38] arXiv:2411.13290 [pdf, html, other]
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Title: Simulating Optical Coherent Nonlinear Response for High-Intensity ExcitationSubjects: Optics (physics.optics); Computational Physics (physics.comp-ph)
Calculation of the coherent nonlinear response of a system is essential to correctly interpret results from advanced techniques such as two-dimensional coherent spectroscopy (2DCS). Usually, even for the simplest systems, such calculations are either performed for low-intensity excitations where perturbative methods are valid and/or by assuming a simplified pulse envelope, such as a {\delta}-function in time. We present exact calculations using the phase-cycling method without making the aforementioned approximations. We introduce a generalized version of the phase-cycling method to isolate an arbitrary N-wave mixing signal. We then apply this method to model the saturation of the nonlinear signal from excitons in semiconductor quantum wells, which is consistent with 2DCS experiments. We also present simulation results that replicate previously-reported experiments with high-intensity excitation of semiconductor quantum dots. By accurately reproducing a variety of phenomena such as higher-order contributions, switching of coherent signal, and changes in photon-echo transients, we prove the efficacy of the phase-cycling method to calculate the coherent nonlinear signal for high-intensity excitation. This method would be particularly useful for systems with multiple, well-separated peaks and/or large inhomogeneity.
- [39] arXiv:2411.13297 [pdf, other]
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Title: Degenerate merging BICs in resonant metasurfacesSubjects: Optics (physics.optics)
Resonant metasurfaces driven by bound states in the continuum (BIC) offer an intriguing approach to engineer high-Q resonances. Merging multiple BICs in the momentum space could further enhance the Q-factor as well as its robustness to fabrication imperfections. Here, we report doubly-degenerate guided mode resonances (GMR) in a resonant metasurface, whose radiation losses could be totally suppressed due to merging BICs. We show that the GMRs and their associated accidental BICs can be evolved into degenerate merging BICs by parametric tuning of the metasurface. Significantly, these two GMRs share the same critical parameter (i.e. lattice constants or thickness) that the merging BICs occur. Interestingly, thanks to the degenerate property of two GMRs, a larger (smaller) period will split one of merging BICs into eight accidental BICs at off-{\Gamma} point, but annihilate the other. Such exotic phenomenon can be well explained from the interaction of GMRs and background Fabry-Perot resonances. Our result provides new strategies to engineering high-Q resonances in resonant metasurfaces for light-matter interaction.
- [40] arXiv:2411.13304 [pdf, other]
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Title: ZnO-based Semiconductors and Structures for Transistors, Optoelectronic Devices and Sustainable ElectronicsComments: 72 pages, 22 figuresSubjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)
Metal oxide thin films are of great interest in scientific advancement, particularly semiconductor thin films in transistors and in a wide range of optoelectronic applications. Many metal oxide thin films attract interest for their electronic bandgap, charge carrier mobility, optical opacity, luminescence, low cost, relative abundance and environmentally-friendly production. Additionally, these properties are often tuneable via particle size, film density, surface morphology, film deposition, growth method, hetero-interface engineering or ion-doping. Zinc oxide as a n-type semiconducting metal oxide is material of great interest owing to its intrinsically wide direct bandgap, high electron mobility, relatively high exciton binding energy, high optical transparency, demonstrated metal-ion doping optoelectronic effects, a range of different particle morphologies and deposition methods, photoluminescence ability, low cost and a variety of existing green synthesis methods. Here, these aspects of zinc oxide and some related oxides are reviewed, focusing on how the unique properties of this metal oxide make it suitable for a range of different applications from thin film transistors, high mobility oxide interfaces, transparent conductive oxides, photoanodes photodetectors, chemical sensors, photocatalysts, superlattice electronics and more. The properties and deposition methods and their impact on functionality will be discussed alongside their role in sustainable optoelectronics for future devices.
- [41] arXiv:2411.13309 [pdf, other]
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Title: Anisotropic manipulation of terahertz spin-waves by spin-orbit torque in a canted antiferromagnetSubjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)
We theoretically and numerically elucidate the electrical control over spin waves in antiferromagnetic materials (AFM) with biaxial anisotropies and Dzyaloshinskii-Moriya interactions. The spin wave dispersion in an AFM manifests as a bifurcated spectrum with distinct high-frequency and low-frequency bands. Utilizing a heterostructure comprised of platinum and the AFM, we demonstrate anisotropic control of spin-wave bands via spin currents with three-dimensional spin polarizations, encompassing both resonant and propagating wave modes. Moreover, leveraging the confined geometry, we explore the possibility of controlling spin waves within a spectral domain ranging from tens of gigahertz to sub-terahertz frequencies. The implications of our findings suggest the potential for developing a terahertz wave source with electrical tunability, thereby facilitating its incorporation into ultrafast, broadband, and wireless communication technologies.
- [42] arXiv:2411.13324 [pdf, html, other]
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Title: An efficient, adaptive solver for accurate simulation of multicomponent shock-interface problems for thermally perfect speciesSubjects: Computational Physics (physics.comp-ph)
A second-order-accurate finite volume method, hybridized by blending an extended double-flux algorithm and a traditionally conservative scheme, is developed. In this scheme, hybrid convective fluxes as well as hybrid interpolation techniques are designed to ensure stability and accuracy in the presence of both material interfaces and shocks. Two computationally efficient approaches, extended from the original double-flux model, are presented to eliminate the well-known "pressure oscillation" phenomenon at material interfaces observed with the traditional conservative scheme. Numerous verification simulations confirm that the method is capable of handling multi-dimensional shock-interface problems reliably and efficiently, even in the presence of viscous and reactive terms.
- [43] arXiv:2411.13328 [pdf, html, other]
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Title: The influence of free-stream turbulence on the fluctuating loads experienced by a cylinder exposed to a turbulent cross-flowSubjects: Fluid Dynamics (physics.flu-dyn)
The impact of several $``\text{flavours}"$ of free-stream turbulence (FST) on the structural response of a cantilevered cylinder, subjected to a turbulent cross-flow is investigated. At high enough Reynolds numbers, the cylinder generates a spectrally rich turbulent wake which significantly contributing to the experienced loads. The presence of FST introduces additional complexity through two primary mechanisms: $\textbf{directly}$, by imposing a fluctuating velocity field on the cylinder's surface, and $\textbf{indirectly}$, by altering the vortex shedding dynamics, modifying the experienced loads. We employ concurrent temporally resolved Particle Image Velocimetry (PIV) and distributed strain measurements using Rayleigh backscattering fibre optic sensors (RBS) to instrument the surrounding velocity field and the structural strain respectively. By using various turbulence-generating grids, and manipulating their distance to the cylinder, we assess a broad FST parameter space allowing us to individually explore the influence of transverse integral length scale ($\mathcal{L}_{13}/D$), and turbulence intensity ($TI$) of the FST on the developing load dynamics. The presence of FST enhances the magnitude of the loads acting on the cylinder. This results from a decreased vortex formation length, increased coherence of regular vortex shedding, and energy associated with this flow structure in the near-wake. The cylinder's structural response is mainly driven by the vortex shedding dynamics, and their modification induced by the presence of FST, ie. the indirect effect outweighs the direct effect. From the explored FST parameter space, $TI$ was seen to be the main driver of enhanced loading conditions, presenting a positive correlation with the fluctuating loads magnitude at the root.
- [44] arXiv:2411.13331 [pdf, html, other]
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Title: Versatile photonic frequency synthetic dimensions using a single Mach-Zehnder-interferometer-assisted device on thin-film lithium niobateZhao-An Wang, Xiao-Dong Zeng, Yi-Tao Wang, Jia-Ming Ren, Chun Ao, Zhi-Peng Li, Wei Liu, Nai-Jie Guo, Lin-Ke Xie, Jun-You Liu, Yu-Hang Ma, Ya-Qi Wu, Shuang Wang, Jian-Shun Tang, Chuan-Feng Li, Guang-Can GuoSubjects: Optics (physics.optics); Quantum Physics (quant-ph)
Investigating physical models with photonic synthetic dimensions has been generating great interest in vast fields of science. The rapid developing thin-film lithium niobate (TFLN) platform, for its numerous advantages including high electro-optic coefficient and scalability, is well compatible with the realization of synthetic dimensions in the frequency together with spatial domain. While coupling resonators with fixed beam splitters is a common experimental approach, it often lacks tunability and limits coupling between adjacent lattices to sites occupying the same frequency domain positions. Here, on the contrary, we conceive the resonator arrays connected by electro-optic tunable Mach-Zehnder interferometers in our configuration instead of fixed beam splitters. By applying bias voltage and RF modulation on the interferometers, our design extends such coupling to long-range scenario and allows for continuous tuning on each coupling strength and synthetic effective magnetic flux. Therefore, our design enriches controllable coupling types that are essential for building programmable lattice networks and significantly increases versatility. As the example, we experimentally fabricate a two-resonator prototype on the TFLN platform, and on this single chip we realize well-known models including tight-binding lattices, topological Hall ladder and Creutz ladder. We directly observe the band structures in the quasi-momentum space and important phenomena such as spin-momentum locking and the Aharonov-Bohm cage effect. These results demonstrate the potential for convenient simulations of more complex models in our configuration.
- [45] arXiv:2411.13347 [pdf, html, other]
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Title: Simulation of Rutherford Cable AC Loss and Magnetization with the Coupled Axial and Transverse Currents MethodComments: 5 pages, 5 figures, presented at ASC 2024Subjects: Accelerator Physics (physics.acc-ph)
The coupled axial and transverse currents (CATI) method was recently introduced to model the AC loss and magnetization in twisted composite superconducting strands with low computational cost and high accuracy. This method involves two-dimensional finite element (FE) models coupled with circuit equations representing the periodicity of the strand. In this paper, we propose to adapt the CATI method to Rutherford cables, which are periodic structures made of transposed superconducting strands. We focus on reproducing the interstrand coupling currents flowing across contact resistances between the strands and we analyze the associated AC loss. We show that results of a reference three-dimensional FE model are accurately reproduced with a strongly reduced computational cost.
- [46] arXiv:2411.13352 [pdf, other]
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Title: New Insights on the High Reconnection Rate and the Diminishment of Ion OutflowCheng-Yu Fan, Shan Wang, Xu-Zhi Zhou, San Lu, Quanming Lu, Prayash Sharma Pyakurel, Qiugang Zong, Zhi-Yang LiuSubjects: Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)
The recently discovered electron-only reconnection has drawn great interests due to abnormal features like lack of ion outflows and high reconnection rates. Using particle-in-cell simulations, we investigate their physical mechanisms. The reconnection rate, when normalized by ion parameters ($R_i$), may appear anomalously high, whereas that normalized by electron parameters ($R_e$) remains ~0.1. We propose that the essence of high $R_i$ is insufficient field line bending outside the electron diffusion region, indicating an incomplete development of the ion diffusion region. It may result from bursty reconnection in thin current sheets, or small system sizes. The ion outflow diminishes at high $\beta_i$ when the gyroradius ($\rho_i$) exceeds the system size. Low-velocity ions still experience notable acceleration from Hall fields. However, a local distribution includes many high-velocity ions that experience random accelerations from different electric fields across $\rho_i$, resulting in near-zero bulk velocities. Our study helps understand reconnection structures and the underlying physics for transitions between different regimes.
- [47] arXiv:2411.13353 [pdf, html, other]
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Title: Miniaturized spectrometer enabled by end-to-end deep learning on large-scale radiative cavity arrayXinyi Zhou, Cheng Zhang, Xiaoyu Zhang, Yi Zuo, Zixuan Zhang, Feifan Wang, Zihao Chen, Hongbin Li, Chao PengComments: 31 pages, 5 figuresSubjects: Optics (physics.optics)
Miniaturized (mini-) spectrometers are highly desirable tools for chemical, biological, and medical diagnostics because of their potential for portable and in situ spectral detection. In this work, we propose and demonstrate a mini-spectrometer that combines a large-scale radiative cavity array with end-to-end deep learning networks. Specifically, we utilize high-Q bound states in continuum cavities with distinct radiation characteristics as the fundamental units to achieve parallel spectral detection. We realize a 36 $\times$ 30 cavity array that spans a wide spectral range from 1525 to 1605 nm with quality factors above 10^4. We further train a deep network with 8000 outputs to directly map arbitrary spectra to array responses excited by the out-of-plane incident. Experimental results demonstrate that the proposed mini-spectrometer can resolve unknown spectra with a resolution of 0.048 nm in a bandwidth of 80 nm and fidelity exceeding 95%, thus offering a promising method for compact, high resolution, and broadband spectroscopy.
- [48] arXiv:2411.13361 [pdf, html, other]
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Title: Integration of Active Learning and MCMC Sampling for Efficient Bayesian Calibration of Mechanical PropertiesComments: 28 pages, 14 figuresSubjects: Computational Physics (physics.comp-ph); Applications (stat.AP); Machine Learning (stat.ML)
Recent advancements in Markov chain Monte Carlo (MCMC) sampling and surrogate modelling have significantly enhanced the feasibility of Bayesian analysis across engineering fields. However, the selection and integration of surrogate models and cutting-edge MCMC algorithms, often depend on ad-hoc decisions. A systematic assessment of their combined influence on analytical accuracy and efficiency is notably lacking. The present work offers a comprehensive comparative study, employing a scalable case study in computational mechanics focused on the inference of spatially varying material parameters, that sheds light on the impact of methodological choices for surrogate modelling and sampling. We show that a priori training of the surrogate model introduces large errors in the posterior estimation even in low to moderate dimensions. We introduce a simple active learning strategy based on the path of the MCMC algorithm that is superior to all a priori trained models, and determine its training data requirements. We demonstrate that the choice of the MCMC algorithm has only a small influence on the amount of training data but no significant influence on the accuracy of the resulting surrogate model. Further, we show that the accuracy of the posterior estimation largely depends on the surrogate model, but not even a tailored surrogate guarantees convergence of the this http URL, we identify the forward model as the bottleneck in the inference process, not the MCMC algorithm. While related works focus on employing advanced MCMC algorithms, we demonstrate that the training data requirements render the surrogate modelling approach infeasible before the benefits of these gradient-based MCMC algorithms on cheap models can be reaped.
- [49] arXiv:2411.13373 [pdf, html, other]
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Title: Upgrade of the Diagnostic Neutral Beam Injector for the RFX-mod2 experimentMarco Barbisan, Marco Boldrin, Luca Cinnirella, Bruno Laterza, Alberto Maistrello, Lionello Marrelli, Federico Molon, Simone Peruzzo, Cesare Taliercio, Marco Valisa, Enrico ZampivaComments: 6 pages (excl. highlights), 8 figures. Contribution to the 33rd Symposium on Fusion Technology (SOFT), 22-27 September 2024. This is a preprint for the "Fusion Engineering and Design" journalSubjects: Plasma Physics (physics.plasm-ph)
Diagnostic Neutral Beam Injectors (DNBI), through the combined use of Charge Exchange Recombination Spectroscopy (CHERS) and Motional Stark effect diagnostics (MSE), are a well-known tool to access important information about magnetically confined plasmas, such as radial profiles of ion temperature, ion flow, impurity content and intensity and direction of the magnetic field. For this purpose, a DNBI was installed and operated in the RFX-mod experiment, which was designed to confine plasma mainly through the Reversed Field Pinch configuration. The DNBI, designed and built by the Budker Institute of Plasma Physics, was based on a source of positive hydrogen ions, accelerated to 50 keV and for an equivalent neutral beam current of about 5 A at the source. The beam could be modulated and the maximum overall duration was 50 ms. With the upgrade of RFX-mod to the present RFX-mod2 machine, the DNBI is being renovated to solve several plant faults and improve the overall reliability of the system. The 50 kV power supply is being improved, as well as the power supplies in the high voltage deck and its insulation transformer. The control system, originally based on CAMAC technology, was redesigned to be fully replaced. This contribution reviews the technical criticalities emerged in the DNBI check-up and the new solutions adopted to make the DNBI operative and more reliable.
- [50] arXiv:2411.13382 [pdf, other]
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Title: Recitation tasks revamped? Evaluation of smartphone experiment tasks in introductory mechanicsSimon Zacharias Lahme (1), Dominik Dorsel (2), Heidrun Heinke (2), Pascal Klein (1), Andreas Müller (3), Christoph Stampfer (2), Sebastian Staacks (2) ((1) University of Göttingen, (2) RWTH Aachen University, (3) University of Geneva)Comments: 21 pages, 19 figures, 10 tablesSubjects: Physics Education (physics.ed-ph)
This study presents an approach to integrate innovative forms of recitation tasks into first-year introductory mechanics, with a primary focus on smartphone-based experimental tasks and additional programming tasks for comparison. Smartphones enable inexpensive physics experiments with digitized first-hand data collection outside lab settings. Such student experiments can enhance homework assignments, breaking down barriers between lectures, recitation groups, and labs, and thereby linking theoretical and experimental aspects of undergraduate physics education. To explore this potential, we implemented and evaluated a sample set of nine smartphone-based experimental tasks and three programming tasks as weekly exercises in a first-year physics course at RWTH Aachen University. Through twelve short surveys involving up to 188 participants, we investigated students' perceptions of learning with the new tasks, focusing on factors such as goal clarity, difficulty, or feasibility at home. In two additional surveys with 108 and 78 participants, students compared the new experimental and programming tasks to each other and to standard recitation tasks based on affective variables. Our findings indicate that the smartphone-based experimental tasks were generally well-suited to the students, which tended to outperform the programming tasks in terms of perceptions of learning with the tasks and affective responses. Overall, students responded positively to the new experimental tasks, with perceptions comparable to, or only partly below those of established standard recitation tasks. Given that most of the experimental tasks were newly implemented "on-the-fly" within a running course, while the standard recitation tasks have been refined over years, these results are encouraging. They suggest that smartphone-based experimental tasks can be successfully integrated into teaching.
- [51] arXiv:2411.13391 [pdf, html, other]
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Title: Impact of Storm Surge and Power Peaking on Tidal-Fluvial Dynamics in Microtidal Neretva River EstuarySubjects: Atmospheric and Oceanic Physics (physics.ao-ph)
This study investigates the interactions between tides, storm surge, river flow, and power peaking in the microtidal Neretva River estuary, Croatia. Based on the existing NS_Tide tool, the study proposes a new non-stationary harmonic model adapted for microtidal conditions, which incorporates linear storm surge, as well as linear and quadratic river discharge terms. This model enhances the NS_Tide's ability to accurately predict water levels from tide-dominated sections downstream to discharge-dominated areas upstream. River discharge was identified as the dominant factor for predicting stage levels at most stations, while the influence of storm surge, though consistent, decreased upstream. Strong tide-river interactions were observed throughout the study domain, with the stationary tidal component consistently contributing to water level fluctuations at all locations, and minimal influence from the tide-surge interaction component. Simulations using the STREAM numerical model were also used to isolate the variability in water levels caused by power peaking. These simulations demonstrated that high-frequency discharge fluctuations due to hydropower plant operations amplify the $S_1$ constituent in upstream river sections and modulate the amplitudes of other tidal constituents in the estuarine and tidal river sections. The proposed method proved highly effective in the microtidal context of the Neretva River and shows potential for adaptation to mesotidal and macrotidal systems.
- [52] arXiv:2411.13393 [pdf, html, other]
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Title: Making molecules by mergoassociation: the role of center-of-mass motionSubjects: Atomic Physics (physics.atom-ph); Chemical Physics (physics.chem-ph); Quantum Physics (quant-ph)
In mergoassociation, two atoms in separate optical traps are combined to form a molecule when the traps are merged. Previous theoretical treatments have considered only the relative motion of the atoms, neglecting coupling to the motion of the center of mass. We develop a theoretical method to include the coupling to center-of-mass motion and consider its consequences for experiments for both weak and strong coupling. We consider the example of RbCs and then extend the treatment to other systems where mergoassociation may be effective, namely RbSr, RbYb and CsYb. We consider the role of the coupling when the traps are anisotropic and the potential use of moveable traps to construct quantum logic gates.
- [53] arXiv:2411.13406 [pdf, html, other]
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Title: Modeling the effect of hydrodynamic wakes in dynamical models of large-scale fish schoolsComments: 28 pages, 19 figures. This paper is considering submission to Physics of FluidsSubjects: Fluid Dynamics (physics.flu-dyn); Biological Physics (physics.bio-ph)
A novel model of the wake of swimming fish is developed and incorporated into a dynamical model of a fish school to explore the effect of hydrodynamics on the emergent behavior in schooling fish. The model incorporates well-established rules for attraction, alignment, and visual detection via a force-momentum balance in the surge, sway, and yaw directions, thereby allowing us to include the effects of body size, shape, and inertia in to the dynamics of fish motion. The key novelty of the model lies in the modeling of the hydrodynamics, which includes not only the potential flow induced by the body of the fish but also the vortex wakes generated by the fish. These hydrodynamic features, as well as the surge, sway, and yaw force coefficients, are parameterized via three-dimensional high-fidelity direct numerical simulations of a carangiform swimmer, thereby enabling a higher degree of realism in these models. The model is used to examine the effect of wake characteristics on the topology and movement of fish schools. The simulations indicate that these wake vortices lead to improved organization within the schools, especially in situations where the social forces are relatively weak.
- [54] arXiv:2411.13413 [pdf, other]
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Title: An air-spaced virtually imaged phased array with 94 MHz resolution for precision spectroscopyComments: 11 pages, 4 figuresSubjects: Optics (physics.optics); Applied Physics (physics.app-ph); Chemical Physics (physics.chem-ph)
We report on an air-spaced virtually imaged phased array (VIPA) spectrometer that resolves the modes of a mid-infrared frequency comb with a repetition rate of 250 MHz, without an optical filter cavity. With a record spectral resolution of 94 MHz for VIPA, the spectrometer enables precision molecular spectroscopy with high resolution, broad spectral coverage and fast data acquisition. We demonstrate the capabilities of the spectrometer by measuring the absorption spectra of molecular species generated in plasmas. Using plasmas of a mixture of nitrogen, hydrogen, and methane at a low pressure of 1.5 mbar, we obtained high-resolution spectra of methane, around 3017 cm$^{-1}$, as well as hydrogen cyanide and ammonia, around 3240 cm$^{-1}$, demonstrating a wide spectral coverage over 290 cm$^{-1}$ (equivalent to 8.7 THz). The spectrometer performance in terms of Allan-Werle deviation and noise-equivalent absorption is discussed. The air-spaced VIPA concept offers a compact and practical spectrometer that harnesses the full potential of a stabilized frequency comb, making it suitable for a wide range of high-precision spectroscopic applications.
- [55] arXiv:2411.13423 [pdf, html, other]
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Title: Online Optimisation of Machine Learning Collision Models to Accelerate Direct Molecular Simulation of Rarefied Gas FlowsSubjects: Fluid Dynamics (physics.flu-dyn); Computational Physics (physics.comp-ph)
We develop an online optimisation algorithm for in situ calibration of collision models in simulations of rarefied gas flows. The online optimised collision models are able to achieve similar accuracy to Direct Molecular Simulation (DMS) at significantly reduced computational cost for 1D normal shocks in argon across a wide range of temperatures and Mach numbers. DMS is a method of simulating rarefied gases which numerically integrates the trajectories of colliding molecules. It often achieves similar fidelity to Molecular Dynamics (MD) simulations, which fully resolve the trajectories of all particles at all times. However, DMS is substantially more computationally expensive than the popular Direct Simulation Monte Carlo (DSMC) method, which uses simple phenomenological models of the collisions. We aim to accelerate DMS by replacing the computationally costly Classical Trajectory Calculations (CTC) with a neural network collision model. A key feature of our approach is that the machine learning (ML) collision model is optimised online during the simulation on a small dataset of CTC trajectories generated in situ during simulations. The online Machine Learning DMS (ML-DMS) is able to reproduce the accuracy of MD and CTC-DMS for 1D normal shocks in argon at a significantly lower computational cost (by a factor of $\sim5$--$15$), at a wide range of physical conditions (Mach numbers $1.55\leq \text{Ma}\leq 50 $, densities $\sim 10^{-4}\text{kg}\text{m}^{-3}$ to $1\text{kg}\text{m}^{-3}$, and temperatures 16K to 300K). We also derive an online optimisation method for calibration of DSMC collision models given a model of the interatomic forces. In our numerical evaluations for 1D normal shocks, the online optimisation method matches or significantly improves the accuracy of VHS (Variable Hard Sphere) DSMC with respect to CTC-DMS (with a $\sim20 \times$ lower computational cost).
- [56] arXiv:2411.13426 [pdf, html, other]
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Title: Compact Blackbody Radiation Atomic Sensor: Measuring Temperature using Optically Excited Atoms in Vapor CellsDavid S. La Mantia, Mingxin Lei, Nikunjkumar Prajapati, Noah Schlossberger, Matthew T. Simons, Christopher L. Holloway, Julia Scherschligt, Stephen P. Eckel, Eric B. NorrgardSubjects: Atomic Physics (physics.atom-ph)
We demonstrate a blackbody radiation thermometer based on optically excited rubidium atoms in a vapor cell. The temperature measurement is fast, with statistical uncertainty as low as 0.1% in one second. We resolve temperature with a precision of 0.04% in the range 308 K to 344 K when averaging for several seconds. Additionally, we describe an extension to this measurement scheme where the device operates as a self-calibrated, or primary, thermometer. We make progress toward realizing a primary thermometer by demonstrating a temperature-dependent self-consistent calibration scheme, with temperature accuracy of order 1% limited by the uncertainty in atomic transition dipole matrix elements.
- [57] arXiv:2411.13434 [pdf, html, other]
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Title: Oscillations of subcritical fast magnetosonic shock boundaries caused by shock reformationComments: 16 pages, 7 figures, accepted for publication in Plasma Physics and Controlled FusionSubjects: Plasma Physics (physics.plasm-ph); High Energy Astrophysical Phenomena (astro-ph.HE)
The evolution of a deformed subcritical fast magnetosonic shock front is compared between two two-dimensional PIC simulations with different orientations of the magnetic field relative to the simulation box. All other initial and simulation conditions are kept identical. Shock boundary oscillations are observed in the simulation where the magnetic field direction is resolved. This oscillation is caused by the reformation of the shock front. One part of the front acts as a shock, while the other functions as a magnetic piston, with both halves changing their states in antiphase. The oscillation period corresponds to the time required for one shock wave to grow as the other collapses. In contrast, the corrugated fast magnetosonic shock does not oscillate in the second simulation, where the magnetic field is oriented out of the simulation plane. This dependence on magnetic field orientation suggests that the shock oscillation is induced by magnetic tension, which is only effective in the first simulation. In both simulations, the shock perturbation does not grow over time, indicating that the shocks are stable. The potential relevance of these findings for the Alfvénic oscillations of the supercritical Earth's bow shock, detected by the MMS multi-spacecraft mission, is also discussed.
- [58] arXiv:2411.13448 [pdf, html, other]
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Title: Taylor Modeling and Comparative Research Containing Aspect-Ratio Dependent Optimization of Three-Dimensional Hk Superjunction MOSFETsSubjects: Applied Physics (physics.app-ph)
This paper presents a comprehensive study on aspect-ratio dependent optimization for specific on-resistance of three-dimensional high-k superjunction MOSFETs. The research introduces a Taylor modeling method, overcoming the computational limitations of the Bessel method. It also employs the Chynoweth model for more accurate breakdown voltage determination. The study provides a comparative analysis of four different superjunction structures, across five aspects: electric field, impact ionization integral, aspect ratio dependent optimization, charge imbalance effect and temperature. The findings offer valuable insights for the manufacturing guidance of superjunction structure selection
- [59] arXiv:2411.13491 [pdf, html, other]
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Title: Neural machine translation of seismic waves for petrophysical inversionJosé Cunha Teixeira, Ludovic Bodet, Agnès Rivière, Santiago G. Solazzi, Amélie Hallier, Alexandrine Gesret, Sanae El Janyani, Marine Dangeard, Amine Dhemaied, Joséphine Boisson GaboriauComments: 70 pages, 33 figuresSubjects: Geophysics (physics.geo-ph)
Effective structural assessment of urban infrastructure is essential for sustainable land use and resilience to climate change and natural hazards. Seismic wave methods are widely applied in these areas for subsurface characterization and monitoring, yet they often rely on time-consuming inversion techniques that fall short in delivering comprehensive geological, hydrogeological, and geomechanical descriptions. Here, we explore the effectiveness of a passive seismic approach coupled with artificial intelligence (AI) for monitoring geological structures and hydrogeological conditions in the context of sinkhole hazard assessment. We introduce a deterministic petrophysical inversion technique based on a language model that decodes seismic wave velocity measurements to infer soil petrophysical and mechanical parameters as textual descriptions. Results successfully delineate 3D subsurface structures with their respective soil nature and mechanical characteristics, while accurately predicting daily water table levels. Validation demonstrates high accuracy, with a normalized root mean square error of 8%, closely rivaling with conventional stochastic seismic inversion methods, while delivering broader insights into subsurface conditions 2,000 times faster. These findings underscore the potential of advanced AI techniques to significantly enhance subsurface characterization across diverse scales, supporting decision-making for natural hazard mitigation.
- [60] arXiv:2411.13492 [pdf, html, other]
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Title: CFD-based design optimization of a 5 kW ducted hydrokinetic turbine with practical constraintsJeongbin Park, Marco Mangano, Sabet Seraj, Bernardo Pacini, Yingqian Liao, Bradford G. Knight, Kartik Naik, Kevin J. Maki, Joaquim R.R.A. Martins, Jing Sun, Yulin PanComments: This work was supported by the US Department of Energy under the award "RAFT: Reconfigurable Array of High-Efficiency Ducted Turbines for Hydrokinetic Energy Harvesting" (Award No. DE-AR0001438)Subjects: Fluid Dynamics (physics.flu-dyn)
Ducted hydrokinetic turbines enhance energy-harvesting efficiency by better conditioning the flow to the blades, which may yield higher power output than conventional freestream turbines for the same reference area. In this work, we present a ducted hydrokinetic turbine design obtained by simultaneously optimizing the duct, blade, and hub geometries. Our optimization framework combines a CFD solver, an adjoint solver, and a gradient-based optimizer to efficiently explore a large design space, together with a feature-based parameterization method to handle the complex geometry. Practical geometrical constraints ensure the manufacturability of the duct in terms of a minimum thickness and the housing of a 5 kW generator within the hub. The optimization converges to a short, thin duct with a rounded leading edge and an elongated hub protruding the duct inlet. The optimized ducted turbine achieves up to 50% efficiency when evaluated by RANS/URANS solvers despite a bulky hub, outperforming the 45% efficiency of the freestream Bahaj turbine featuring the same hub. This work showcases the effectiveness of CFD-based optimization in advancing ducted turbine designs and demonstrates the hydrodynamic benefits of a ducted configuration, paving the way for future research and real-world applications.
- [61] arXiv:2411.13495 [pdf, html, other]
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Title: Diffraction theories for off-Bragg replay: J.T. Sheridan's seminal work and consequencesComments: 15 pages, 6 Figures, Memento late J.T. SheridanJournal-ref: Asian Journal of Physics, Vol 32 (5-8), p 319 (2023)Subjects: Optics (physics.optics)
Based on the seminal work by John T. Sheridan [1] we discuss the usefulness and validity of simple diffraction theories frequently used to determine and characterize optical holographic gratings. Experimental investigations obtained in recent years highlight the correctness of his analysis which favours an alternative approach over the most widely used Kogelnik theory.
- [62] arXiv:2411.13515 [pdf, html, other]
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Title: Optimization of Second-Order Transport Models for Transition-Continuum FlowsSubjects: Fluid Dynamics (physics.flu-dyn); Computational Physics (physics.comp-ph)
Modeling transition-continuum hypersonic flows poses significant challenges due to thermodynamic nonequilibrium and the associated breakdown of the continuum assumption. Standard continuum models such as the Navier-Stokes equations are inaccurate for these flows, and molecular models can be inefficient due to the large number of computational particles required at moderately high densities. We explore computational modeling of transition-continuum flows using a second-order constitutive theory that provides closures for the terms representing the molecular transport of momentum and energy. We optimize the second-order model parameters for one-dimensional viscous shocks using an adjoint-based optimization method, with the objective function comprising the primitive flow variables. Target data is obtained from moments of distribution functions obtained by solving the Boltzmann equation. We compare results using optimized second-order models, the unoptimized second-order model, and the first-order Navier-Stokes model for Mach numbers $M\in[1.1,10]$ and observe improvements to the shock profiles and shock thickness calculations. We validate the optimized models by comparing the predicted viscous stress and heat flux, which are not included in the objective function, to those obtained by integrating the distribution function. The close match to these moments indicates that the satisfactory performance of the optimized second-order models is consistent with the nonequilibrium flow physics.
- [63] arXiv:2411.13530 [pdf, other]
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Title: Towards Linking Histological Changes to Liver Viscoelasticity: A Hybrid Analytical-Computational Micromechanics ApproachComments: 15 pages, 7 figuresSubjects: Biological Physics (physics.bio-ph)
Motivated by elastography that utilizes tissue mechanical properties as biomarkers for liver disease, and the eventual objective of providing explicit links between histology and bulk mechanical properties, we develop a micromechanical modeling approach to capture the effects of fat and collagen deposition in the liver. Specifically, we utilize computational homogenization to convert the microstructural changes in hepatic lobule to the effective viscoelastic modulus of the liver tissue, i.e. predict the bulk material properties by analyzing the deformation of repeating unit cell. The lipid and collagen deposition is simulated with the help of ad hoc algorithms informed by histological observations. Collagen deposition is directly included in the computational model, while composite material theory is used to convert fat content to the microscopic mechanical properties. The results illustrate the ability of the model to capture the effect of both fat and collagen deposition on the viscoelastic moduli and represents a step towards linking histological changes in the liver to its bulk mechanical properties, which can provide insights for accurate diagnosis with elastography.
New submissions (showing 63 of 63 entries)
- [64] arXiv:2411.12794 (cross-list from quant-ph) [pdf, html, other]
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Title: A Universal Protocol for Quantum-Enhanced Sensing via Information ScramblingBryce Kobrin, Thomas Schuster, Maxwell Block, Weijie Wu, Bradley Mitchell, Emily Davis, Norman Y. YaoSubjects: Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas); Statistical Mechanics (cond-mat.stat-mech); Atomic Physics (physics.atom-ph)
We introduce a novel protocol, which enables Heisenberg-limited quantum-enhanced sensing using the dynamics of any interacting many-body Hamiltonian. Our approach - dubbed butterfly metrology - utilizes a single application of forward and reverse time evolution to produce a coherent superposition of a "scrambled" and "unscrambled" quantum state. In this way, we create metrologically-useful long-range entanglement from generic local quantum interactions. The sensitivity of butterfly metrology is given by a sum of local out-of-time-order correlators (OTOCs) - the prototypical diagnostic of quantum information scrambling. Our approach broadens the landscape of platforms capable of performing quantum-enhanced metrology; as an example, we provide detailed blueprints and numerical studies demonstrating a route to scalable quantum-enhanced sensing in ensembles of solid-state spin defects.
- [65] arXiv:2411.12815 (cross-list from astro-ph.HE) [pdf, html, other]
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Title: Multi-Mission Observations of Relativistic Electrons and High-Speed Jets Linked to Shock Generated TransientsSavvas Raptis, Martin Lindberg, Terry Z. Liu, Drew L. Turner, Ahmad Lalti, Yufei Zhou, Primož Kajdič, Athanasios Kouloumvakos, David G. Sibeck, Laura Vuorinen, Adam Michael, Mykhaylo Shumko, Adnane Osmane, Eva Krämer, Lucile Turc, Tomas Karlsson, Christos Katsavrias, Lynn B. Wilson III, Hadi Madanian, Xóchitl Blanco-Cano, Ian J. Cohen, C. Philippe EscoubetSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)
Shock-generated transients, such as hot flow anomalies (HFAs), upstream of planetary bow shocks, play a critical role in electron acceleration. Using multi-mission data from NASA's Magnetospheric Multiscale (MMS) and ESA's Cluster missions, we demonstrate the transmission of HFAs through Earth's quasi-parallel bow shock, associated with acceleration of electrons up to relativistic energies. Energetic electrons, initially accelerated upstream, are shown to remain broadly confined within the transmitted transient structures downstream, where betatron acceleration further boosts their energy due to elevated compression levels. Additionally, high-speed jets form at the compressive edges of HFAs, exhibiting a significant increase in dynamic pressure and potentially contributing to driving further localized compression. Our findings emphasize the efficiency of quasi-parallel shocks in driving particle acceleration far beyond the immediate shock transition region, expanding the acceleration region to a larger spatial domain. Finally, this study underscores the importance of multi-scale observational approach in understanding the convoluted processes behind collisionless shock physics and their broader implications.
- [66] arXiv:2411.12834 (cross-list from astro-ph.IM) [pdf, html, other]
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Title: Bringing together African & European research communities with an inclusive astronomy conferenceChris M. Harrison (Newcastle University), Leah Morabito (Durham University, on behalf of the Organising Committees)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA); Physics Education (physics.ed-ph); Physics and Society (physics.soc-ph)
We report on an international scientific conference, where we brought together the African and European academic astronomy communities. This conference aimed to bridge the gap between those in position of privilege, with ease of access to international networking events (i.e., the typical experience of those affiliated with Western institutions), with those who have been historically excluded (affecting the majority of African scientists/institutions). We describe how we designed the conference around cutting-edge problems in the research field, but with a large focus on building networking and professional relationships. Significant effort went into: (1) ensuring a diverse representation of participants; (2) practically and financially supporting those who may have never attended an international conference and; (3) creating an inclusive and supportive environment through a careful programme of activities, both before and during the event. Throughout this process maintaining scientific integrity was a core commitment. We summarise some of the successes, challenges, and lessons learnt from organising this conference. We also present feedback obtained from participants, which demonstrates an overall achievement of our objectives. This is all combined to provide some key recommendations for any groups, from any research field, who wishes to lead similar initiatives.
- [67] arXiv:2411.12864 (cross-list from cond-mat.mtrl-sci) [pdf, html, other]
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Title: Inverse Faraday effect in 3d, 4d, and 5d transition metalsComments: 13 pages, 14 figuresSubjects: Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph)
Using first-principles calculations, we systematically investigate the spin contributions to the inverse Faraday effect (IFE) in transition metals. The IFE is primarily driven by spin-orbit coupling (SOC)-induced asymmetry between excited electron and hole spin moments. Our results reveal that even elements with smaller electron magnetic moments, like Os, can exhibit higher IFE due to greater electron-hole asymmetry. Pt shows the highest IFE in the 1 - 2 eV frequency range, while Os dominates in the 2 - 4 eV range. In addition, we demonstrate that the IFE of neighboring elements with similar crystal structures (e.g., Ir, Pt, and Au) can be tuned by adjusting their Fermi levels, indicating the importance of d electron filling on IFE. Finally, we find that the trend in electron (or hole) contributions to the IFE closely follows that of the spin Hall conductivity (SHC), however, the total IFE involves more complex interactions.
- [68] arXiv:2411.12869 (cross-list from eess.SY) [pdf, html, other]
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Title: Omnidirectional Wireless Power Transfer for Millimetric Magnetoelectric Biomedical ImplantsWei Wang, Zhanghao Yu, Yiwei Zou, Joshua E Woods, Prahalad Chari, Yumin Su, Jacob T Robinson, Kaiyuan YangComments: 13 pages, 27 figuresJournal-ref: IEEE Journal of Solid-State Circuits, Volume: 59, Issue: 11, Page(s): 3599 - 3611, November 2024Subjects: Systems and Control (eess.SY); Medical Physics (physics.med-ph)
Miniature bioelectronic implants promise revolutionary therapies for cardiovascular and neurological disorders. Wireless power transfer (WPT) is a significant method for miniaturization, eliminating the need for bulky batteries in devices. Despite successful demonstrations of millimetric battery free implants in animal models, the robustness and efficiency of WPT are known to degrade significantly under misalignment incurred by body movements, respiration, heart beating, and limited control of implant orientation during surgery. This article presents an omnidirectional WPT platform for millimetric bioelectronic implants, employing the emerging magnetoelectric (ME) WPT modality, and magnetic field steering technique based on multiple transmitter (TX) coils. To accurately sense the weak coupling in a miniature implant and adaptively control the multicoil TX array in a closed loop, we develop an active echo (AE) scheme using a tiny coil on the implant. Our prototype comprises a fully integrated 14.2 mm3 implantable stimulator embedding a custom low power system on chip (SoC) powered by an ME film, a TX with a custom three channel AE RX chip, and a multicoil TX array with mutual inductance cancellation. The AE RX achieves negative 161 dBm per Hz input referred noise with 64 dB gain tuning range to reliably sense the AE signal, and offers fast polarity detection for driver control. AE simultaneously enhances the robustness, efficiency, and charging range of ME WPT. Under 90 degree rotation from the ideal position, our omnidirectional WPT system achieves 6.8x higher power transfer efficiency (PTE) than a single coil baseline. The tracking error of AE negligibly degrades the PTE by less than 2 percent from using ideal control.
- [69] arXiv:2411.12875 (cross-list from cond-mat.mtrl-sci) [pdf, html, other]
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Title: Magnetoelastic Interactions Reduce Hysteresis in Soft MagnetsSubjects: Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph)
The width of the magnetic hysteresis loop is often correlated with the material's magnetocrystalline anisotropy constant $\kappa_1$. Traditionally, a common approach to reduce the hysteresis width has been to develop alloys with $\kappa_1$ as close to zero as possible. However, contrary to this widely accepted view, we present evidence that magnetoelastic interactions governed by magnetostriction constants, elastic stiffness, and applied stresses play an important role in reducing magnetic hysteresis width, despite large $\kappa_1$ values. We use a nonlinear micromagnetics framework to systematically investigate the interplay between material constants $\lambda_{100}$, $c_{11}$, $c_{12}$, $\kappa_1$, applied or residual stresses $\sigma_{\mathrm{R}}$, and needle domains to collectively lower the energy barrier for magnetization reversal. A distinguishing feature of our work is that we correlate the energy barrier governing the growth of needle domains with the width of the hysteresis loop. This energy barrier approach enables us to capture the nuanced interplay between anisotropy constant, magnetostriction, and applied stresses, and their combined influence on magnetic hysteresis. We propose a mathematical relationship on the coercivity map: $\kappa_1 = \alpha(c_{11}-c_{12})(\lambda_{100}+\beta\sigma_{11})^2$ for which magnetic hysteresis can be minimized for a uniaxial residual stress $\sigma_\mathrm{R} = \sigma_{11}\hat{\mathbf{e}}_1\otimes\hat{\mathbf{e}}_1$ (and for some constants $\alpha$, $\beta$). These results serve as quantitative guidelines to design magnetic alloys with small hysteresis, and potentially guide the discovery of a new generation of soft magnets located beyond the $\kappa_1 \to 0$ region.
- [70] arXiv:2411.12894 (cross-list from quant-ph) [pdf, html, other]
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Title: The time-dependent quantum harmonic oscillator: a pedagogical approach via the Lewis-Riesenfeld dynamical invariant methodComments: 19 pages, 4 figuresSubjects: Quantum Physics (quant-ph); Physics Education (physics.ed-ph)
In quantum mechanics courses, students often solve the Schrödinger equation for the harmonic oscillator with time-independent parameters. However, time-dependent quantum harmonic oscillators (TDHOs) are relevant in modeling several problems as, for instance, the description of quantum motion of particles in traps, in shortcuts to adiabaticity, as well as in quantum scalar fields evolving in expanding universes. In the present paper, we discuss, with a pedagogical approach, the TDHO with time-dependent frequency via the Lewis-Riesenfeld dynamical invariant method, revisiting the main steps to obtain the wave function associated with this model, and briefly discussing the relationship between this oscillator and the generation of squeezed states. As examples of pedagogical applications of TDHOs and the Lewis-Riesenfeld method in quantum mechanics courses, we solve the following problems: the calculation of the transition probability associated with a TDHO which undergoes jumps in its frequency, and the analysis of the dynamics of a quantum particle in a Paul trap.
- [71] arXiv:2411.12897 (cross-list from cs.LG) [pdf, html, other]
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Title: Tree Species Classification using Machine Learning and 3D Tomographic SAR -- a case study in Northern EuropeJournal-ref: Neurips 2024 - Climate Change WorkshopSubjects: Machine Learning (cs.LG); Computer Vision and Pattern Recognition (cs.CV); Data Analysis, Statistics and Probability (physics.data-an)
Tree species classification plays an important role in nature conservation, forest inventories, forest management, and the protection of endangered species. Over the past four decades, remote sensing technologies have been extensively utilized for tree species classification, with Synthetic Aperture Radar (SAR) emerging as a key technique. In this study, we employed TomoSense, a 3D tomographic dataset, which utilizes a stack of single-look complex (SLC) images, a byproduct of SAR, captured at different incidence angles to generate a three-dimensional representation of the terrain. Our research focuses on evaluating multiple tabular machine-learning models using the height information derived from the tomographic image intensities to classify eight distinct tree species. The SLC data and tomographic imagery were analyzed across different polarimetric configurations and geosplit configurations. We investigated the impact of these variations on classification accuracy, comparing the performance of various tabular machine-learning models and optimizing them using Bayesian optimization. Additionally, we incorporated a proxy for actual tree height using point cloud data from Light Detection and Ranging (LiDAR) to provide height statistics associated with the model's predictions. This comparison offers insights into the reliability of tomographic data in predicting tree species classification based on height.
- [72] arXiv:2411.12904 (cross-list from quant-ph) [pdf, html, other]
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Title: Quantum Teleportation with Telecom Photons from Remote Quantum EmittersTim Strobel, Michal Vyvlecka, Ilenia Neureuther, Tobias Bauer, Marlon Schäfer, Stefan Kazmaier, Nand Lal Sharma, Raphael Joos, Jonas H. Weber, Cornelius Nawrath, Weijie Nie, Ghata Bhayani, Caspar Hopfmann, Christoph Becher, Peter Michler, Simone Luca PortalupiSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
The quest for a global quantum internet is based on the realization of a scalable network which requires quantum hardware with exceptional performance. Among them are quantum light sources providing deterministic, high brightness, high-fidelity entangled photons and quantum memories with coherence times in the millisecond range and above. To operate the network on a global scale, the quantum light source should emit at telecommunication wavelengths with minimum propagation losses. A cornerstone for the operation of such a quantum network is the demonstration of quantum teleportation. Here we realize full-photonic quantum teleportation employing one of the most promising platforms, i.e. semiconductor quantum dots, which can fulfill all the aforementioned requirements. Two remote quantum dots are used, one as a source of entangled photon pairs and the other as a single-photon source. The frequency mismatch between the triggered sources is erased using two polarization-preserving quantum frequency converters, enabling a Bell state measurement at telecommunication wavelengths. A post-selected teleportation fidelity of up to 0.721(33) is achieved, significantly above the classical limit, demonstrating successful quantum teleportation between light generated by distinct sources. These results mark a major advance for the semiconductor platform as a source of quantum light fulfilling a key requirement for a scalable quantum network. This becomes particularly relevant after the seminal breakthrough of addressing a nuclear spin in semiconductor quantum dots demonstrating long coherence times, thus fulfilling another crucial step towards a scalable quantum network.
- [73] arXiv:2411.12938 (cross-list from stat.CO) [pdf, html, other]
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Title: Probability distributions and calculations for Hake's ratio statistics in measuring effect sizeComments: 23 pages, 5 figures, 1 tableSubjects: Computation (stat.CO); Data Analysis, Statistics and Probability (physics.data-an)
Ratio statistics and distributions play a crucial role in various fields, including linear regression, metrology, nuclear physics, operations research, econometrics, biostatistics, genetics, and engineering. In this work, we examine the statistical properties and probability calculations of the Hake normalized gain as a measure of effect size and educational effectiveness in physics education. Leveraging existing knowledge about the Hake ratio as a ratio of normal variables and utilizing open data science tools, we developed two novel computational approaches for computing ratio distributions. Our pilot numerical study demonstrates the speed, accuracy, and reliability of calculating ratio distributions through (1) DE quadrature with/without barycentric interpolation, a very quick and efficient quadrature method, and (2) a 2D vectorized numerical inversion of characteristic functions, which offers broader applicability by not requiring knowledge of PDFs or the independence of ratio constituents. These numerical explorations not only deepen the understanding of the Hake ratio's distribution but also showcase the efficiency, precision, and versatility of our proposed methods, making them highly suitable for fast data analysis based on exact probability ratio distributions. This capability has potential applications in multidimensional statistics and uncertainty analysis in metrology, where precise and reliable data handling is essential.
- [74] arXiv:2411.12942 (cross-list from quant-ph) [pdf, html, other]
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Title: The Influence of Thermal Fluctuations on Bosonic Correlations and the AC Stark Effect in Two-Level Atoms: A Superstatistical PerspectiveComments: 16 pages, 6 figuresSubjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); Optics (physics.optics)
We study the influence of thermal fluctuations on the two-time correlation functions of bosonic baths within a superstatistics framework by assuming that fluctuations follow the gamma distribution. We further establish a connection between superstatistics and Tsallis non-additive thermodynamics by introducing a temperature-renormalizing parameter. Our results show that, for an Ohmic model, the system's correlation functions exhibit diverse time-dependent behaviors, with the real and imaginary parts displaying enhancement or suppression depending on temperature and fluctuation strength. Additionally, we analyze the impact of these fluctuations on the quantum master equation of a damped two-level atom coupled to an out-of-equilibrium radiation bath. We demonstrate that while the equation's algebraic structure remains intact, the coupling constants are modified by the fluctuation parameters and cavity volume. Specifically, we observe that the AC Stark effect undergoes significant modifications, with fluctuations influencing the transition between repulsive and attractive energy levels.
- [75] arXiv:2411.12948 (cross-list from cs.LG) [pdf, html, other]
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Title: Machine learned reconstruction of tsunami dynamics from sparse observationsSubjects: Machine Learning (cs.LG); Fluid Dynamics (physics.flu-dyn)
We investigate the use of the Senseiver, a transformer neural network designed for sparse sensing applications, to estimate full-field surface height measurements of tsunami waves from sparse observations. The model is trained on a large ensemble of simulated data generated via a shallow water equations solver, which we show to be a faithful reproduction for the underlying dynamics by comparison to historical events. We train the model on a dataset consisting of 8 tsunami simulations whose epicenters correspond to historical USGS earthquake records, and where the model inputs are restricted to measurements obtained at actively deployed buoy locations. We test the Senseiver on a dataset consisting of 8 simulations not included in training, demonstrating its capability for extrapolation. The results show remarkable resolution of fine scale phase and amplitude features from the true field, provided that at least a few of the sensors have obtained a non-zero signal. Throughout, we discuss which forecasting techniques can be improved by this method, and suggest ways in which the flexibility of the architecture can be leveraged to incorporate arbitrary remote sensing data (eg. HF Radar and satellite measurements) as well as investigate optimal sensor placements.
- [76] arXiv:2411.13018 (cross-list from cond-mat.mtrl-sci) [pdf, other]
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Title: Comparison of Kikuchi Diffraction Geometries in Scanning Electron MicroscopeSubjects: Materials Science (cond-mat.mtrl-sci); Instrumentation and Detectors (physics.ins-det)
Recent advances in scanning electron microscope (SEM) based Kikuchi diffraction have demonstrated the important potential for reflection and transmission methods, like transmission Kikuchi diffraction (TKD) and electron backscatter diffraction (EBSD). Furthermore, with the advent of compact direct electron detectors (DED) it has been possible to place the detector in a variety of configurations within the SEM chamber. This motivates the present work where we explore the similarities and differences of the different geometries that include on-axis TKD & off-axis TKD using electron transparent samples, as well as more conventional EBSD. Furthermore, we compare these with the newest method called "reflection Kikuchi diffraction" RKD where the sample is placed flat in the chamber and the detector is placed below the pole piece. Through remapping collected diffraction patterns, all these methods can be used to generate an experimental "diffraction sphere" that can be used to explore diffraction from any scattering vector from the unit cell, as well as the ability to perform band profile analysis. This diffraction sphere approach enables us to further probe specific differences between the methods, including for example thickness effects in TKD that can result in the generation of diffraction spots, as well as electron scattering path length effects that result in excess and deficiency variations, as well as inversion of bands in experimental patterns.
- [77] arXiv:2411.13087 (cross-list from cond-mat.mes-hall) [pdf, html, other]
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Title: Time-resolved diamond magnetic microscopy of superparamagnetic iron-oxide nanoparticlesB. A. Richards, N. Ristoff, J. Smits, A. Jeronimo Perez, I. Fescenko, M. D. Aiello, F. Hubert, Y. Silani, N. Mosavian, M. Saleh Ziabari, A. Berzins, J. T. Damron, P. Kehayias, D. L. Huber, A. M. Mounce, M. P. Lilly, T. Karaulanov, A. Jarmola, A. Laraoui, V. M. AcostaComments: Main text: 8 pages, 5 figures. Entire manuscript including Appendices: 28 pages, 22 figuresSubjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); Instrumentation and Detectors (physics.ins-det); Medical Physics (physics.med-ph); Quantum Physics (quant-ph)
Superparamagnetic iron-oxide nanoparticles (SPIONs) are promising probes for biomedical imaging, but the heterogeneity of their magnetic properties is difficult to characterize with existing methods. Here, we perform widefield imaging of the stray magnetic fields produced by hundreds of isolated ~30-nm SPIONs using a magnetic microscope based on nitrogen-vacancy centers in diamond. By analyzing the SPION magnetic field patterns as a function of applied magnetic field, we observe substantial field-dependent transverse magnetization components that are typically obscured with ensemble characterization methods. We find negligible hysteresis in each of the three magnetization components for nearly all SPIONs in our sample. Most SPIONs exhibit a sharp Langevin saturation curve, enumerated by a characteristic polarizing applied field, B_c. The B_c distribution is highly asymmetric, with a standard deviation (1.4 mT) that is larger than the median (0.6 mT). Using time-resolved magnetic microscopy, we directly record SPION Néel relaxation, after switching off a 31 mT applied field, with a temporal resolution of ~60 ms that is limited by the ring-down time of the electromagnet coils. For small bias fields B_{hold}=1.5-3.5 mT, we observe a broad range of SPION Néel relaxation times--from milliseconds to seconds--that are consistent with an exponential dependence on B_{hold}. Our time-resolved diamond magnetic microscopy study reveals rich SPION sample heterogeneity and may be extended to other fundamental studies of nanomagnetism.
- [78] arXiv:2411.13106 (cross-list from quant-ph) [pdf, html, other]
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Title: Quantum uncertainty of optical coherenceSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
Light is known to exhibit quantum uncertainty in terms of its amplitude, phase, and polarization. However, quantum uncertainty related to coherence, which is also a fundamental physical property of light, has not been considered to date. Here, we formulate and explore the concept of quantum optical coherence uncertainty. We focus on the first-order coherence of the simplest possible light field, a purely monochromatic plane wave, which is classically completely stable. Starting from a scalar treatment, we show that the field displays zero coherence uncertainty only for a number state. We then proceed to the vectorial regime and establish that any state leads to coherence fluctuations, governed by a set of uncertainty relations depending on the polarization state and space-time points. Our work thus provides fundamental insights into the quantum character of optical coherence, with potential benefits in applications using highly sensitive interferometric and polarimetric techniques.
- [79] arXiv:2411.13114 (cross-list from quant-ph) [pdf, html, other]
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Title: Quantum versatility in PageRankComments: 12pagesJournal-ref: Phys. Rev. Research 6, 043163 (2024)Subjects: Quantum Physics (quant-ph); Physics and Society (physics.soc-ph)
Quantum mechanics empowers the emergence of quantum advantages in various fields, including quantum algorithms. Quantum PageRank is a promising tool for a future quantum internet. Recently, arbitrary phase rotations (APR) have been introduced in the underlying Szegedy's quantum walk of quantum PageRank algorithm. In this work, we thoroughly study the role APR plays in quantum PageRank. We discover the versatility resulting from quantumness. Specifically, we discover the emergence of a cluster phenomenon in rankings considering the rotation phases, i.e. the existence of similar clusters in the distribution of the rankings and their fidelity with the corresponding classical PageRanks, the ranking distribution variance, the coherence and entanglement of PageRank states, and the power law parameter in the ranking distributions on a scale-free network concerning the two rotation phases. Furthermore, we propose an alternate quantum PageRank with APR which provides an extra tunnel for the analysis of PageRank. We also study the PageRank on the trackback graph of a scale-free graph for the investigation of network information traffic tracking. We demonstrate the rich cluster diversity formed in our alternate quantum PageRank, which offers a novel perspective on the quantum versatility of PageRank. Our results present the quantum-enabled perspective for PageRanking and shed light on the design and application of practical quantum PageRank algorithms.
- [80] arXiv:2411.13120 (cross-list from cs.CV) [pdf, other]
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Title: Virtual Staining of Label-Free Tissue in Imaging Mass SpectrometryYijie Zhang, Luzhe Huang, Nir Pillar, Yuzhu Li, Lukasz G. Migas, Raf Van de Plas, Jeffrey M. Spraggins, Aydogan OzcanComments: 33 Pages, 6 FiguresSubjects: Computer Vision and Pattern Recognition (cs.CV); Machine Learning (cs.LG); Medical Physics (physics.med-ph); Optics (physics.optics)
Imaging mass spectrometry (IMS) is a powerful tool for untargeted, highly multiplexed molecular mapping of tissue in biomedical research. IMS offers a means of mapping the spatial distributions of molecular species in biological tissue with unparalleled chemical specificity and sensitivity. However, most IMS platforms are not able to achieve microscopy-level spatial resolution and lack cellular morphological contrast, necessitating subsequent histochemical staining, microscopic imaging and advanced image registration steps to enable molecular distributions to be linked to specific tissue features and cell types. Here, we present a virtual histological staining approach that enhances spatial resolution and digitally introduces cellular morphological contrast into mass spectrometry images of label-free human tissue using a diffusion model. Blind testing on human kidney tissue demonstrated that the virtually stained images of label-free samples closely match their histochemically stained counterparts (with Periodic Acid-Schiff staining), showing high concordance in identifying key renal pathology structures despite utilizing IMS data with 10-fold larger pixel size. Additionally, our approach employs an optimized noise sampling technique during the diffusion model's inference process to reduce variance in the generated images, yielding reliable and repeatable virtual staining. We believe this virtual staining method will significantly expand the applicability of IMS in life sciences and open new avenues for mass spectrometry-based biomedical research.
- [81] arXiv:2411.13190 (cross-list from quant-ph) [pdf, html, other]
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Title: Ab-initio approach to Many-Body Quantum Spin DynamicsComments: 12 pages, 9 figuresSubjects: Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph); Computational Physics (physics.comp-ph)
A fundamental longstanding problem in studying spin models is the efficient and accurate numerical simulation of the long-time behavior of larger systems. The exponential growth of the Hilbert space and the entanglement accumulation at long times pose major challenges for current methods. To address these issues, we employ the multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) framework to simulate the many-body spin dynamics of the Heisenberg model in various settings, including the Ising and XYZ limits with different interaction ranges and random couplings. Benchmarks with analytical and exact numerical approaches show that ML-MCTDH accurately captures the time evolution of one- and two-body observables in both one- and two-dimensional lattices. A comparison of ML-MCTDH with the discrete truncated Wigner approximation (DTWA) demonstrates that our approach excels in handling anisotropic models and consistently provides better results for two-point observables in all simulation instances. Our results indicate that the multilayer structure of ML-MCTDH is a promising numerical framework for handling the dynamics of generic many-body spin systems.
- [82] arXiv:2411.13241 (cross-list from cs.ET) [pdf, other]
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Title: Advanced Plaque Modeling for Atherosclerosis Detection Using Molecular CommunicationAlexander Wietfeld, Pit Hofmann, Jonas Fuchtmann, Pengjie Zhou, Ruifeng Zheng, Juan A. Cabrera, Frank H.P. Fitzek, Wolfgang KellererComments: 6 pages, 6 figuresSubjects: Emerging Technologies (cs.ET); Medical Physics (physics.med-ph)
As one of the most prevalent diseases worldwide, plaque formation in human arteries, known as atherosclerosis, is the focus of many research efforts. Previously, molecular communication (MC) models have been proposed to capture and analyze the natural processes inside the human body and to support the development of diagnosis and treatment methods. In the future, synthetic MC networks are envisioned to span the human body as part of the Internet of Bio-Nano Things (IoBNT), turning blood vessels into physical communication channels. By observing and characterizing changes in these channels, MC networks could play an active role in detecting diseases like atherosclerosis. In this paper, building on previous preliminary work for simulating an MC scenario in a plaque-obstructed blood vessel, we evaluate different analytical models for non-Newtonian flow and derive associated channel impulse responses (CIRs). Additionally, we add the crucial factor of flow pulsatility to our simulation model and investigate the effect of the systole-diastole cycle on the received particles across the plaque channel. We observe a significant influence of the plaque on the channel in terms of the flow profile and CIR across different emission times in the cycle. These metrics could act as crucial indicators for early non-invasive plaque detection in advanced future MC methods.
- [83] arXiv:2411.13313 (cross-list from quant-ph) [pdf, html, other]
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Title: Anomalous dependence of sensitivity on observation time induced by time crystal orderSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
In this letter, we consider a composite atom-cavity system interacting with a ring resonator. In such a system, time crystal regime can be observed. We show that this regime can lead to a quadratic observation time dependence of the system's sensitivity to perturbations due to ability to retain the memory of the atom's initial state. Outside the time crystal regime, the system is not able to retain the memory of the atom's initial state and the sensitivity scales linearly on the observation time. Our results open up a new way for implementation of discrete time crystals in sensing and metrology.
- [84] arXiv:2411.13357 (cross-list from cond-mat.soft) [pdf, html, other]
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Title: Topological comparison of flexible and semiflexible chains in polymer melts with $\theta$-chainsComments: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Chem. Phys. 161, 144904 (2024) and may be found at this https URLJournal-ref: J. Chem. Phys. 161, 144904 (2024)Subjects: Soft Condensed Matter (cond-mat.soft); Statistical Mechanics (cond-mat.stat-mech); Computational Physics (physics.comp-ph)
A central paradigm of polymer physics states that chains in melts behave like random walks as intra- and interchain interactions effectively cancel each other out. Likewise, $\theta$-chains, i.e., chains at the transition from a swollen coil to a globular phase, are also thought to behave like ideal chains, as attractive forces are counterbalanced by repulsive entropic contributions. While the simple mapping to an equivalent Kuhn chain works rather well in most scenarios with corrections to scaling, random walks do not accurately capture the topology and knots particularly for flexible chains. In this paper, we demonstrate with Monte Carlo and molecular dynamics simulations that chains in polymer melts and $\theta$-chains not only agree on a structural level for a range of stiffnesses, but also topologically. They exhibit similar knotting probabilities and knot sizes, both of which are not captured by ideal chain representations. This discrepancy comes from the suppression of small knots in real chains, which is strongest for very flexible chains because excluded volume effects are still active locally and become weaker with increasing semiflexibility. Our findings suggest that corrections to ideal behavior are indeed similar for the two scenarios of real chains and that structure and topology of a chain in a melt can be approximately reproduced by a corresponding $\theta$-chain.
- [85] arXiv:2411.13364 (cross-list from cond-mat.stat-mech) [pdf, html, other]
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Title: Effective dimensional reduction of complex systems based on tensor networksComments: 27 pages, 12 figuresSubjects: Statistical Mechanics (cond-mat.stat-mech); Social and Information Networks (cs.SI); Physics and Society (physics.soc-ph)
The exact treatment of Markovian models of complex systems requires knowledge of probability distributions exponentially large in the number of components $n$. Mean-field approximations provide an effective reduction in complexity of the models, requiring only a number of phase space variables polynomial in system size. However, this comes at the cost of losing accuracy close to critical points in the systems dynamics and an inability to capture correlations in the system. In this work, we introduce a tunable approximation scheme for Markovian spreading models on networks based on Matrix Product States (MPS). By controlling the bond dimensions of the MPS, we can investigate the effective dimensionality needed to accurately represent the exact $2^n$ dimensional steady-state distribution. We introduce the entanglement entropy as a measure of the compressibility of the system and find that it peaks just after the phase transition on the disordered side, in line with the intuition that more complex states are at the 'edge of chaos'. We compare the accuracy of the MPS with exact methods on different types of small random networks and with Markov Chain Monte Carlo methods for a simplified version of the railway network of the Netherlands with 55 nodes. The MPS provides a systematic way to tune the accuracy of the approximation by reducing the dimensionality of the systems state vector, leading to an improvement over second-order mean-field approximations for sufficiently large bond dimensions.
- [86] arXiv:2411.13397 (cross-list from math.AP) [pdf, html, other]
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Title: Stability of the Inviscid Power-Law Vortex in Self-Similar CoordinatesComments: 21 pagesSubjects: Analysis of PDEs (math.AP); Fluid Dynamics (physics.flu-dyn)
We prove that the stationary power-law vortex $\overline{\omega}(x) = \beta |x|^{-\alpha}$, which explicitly solves the incompressible Euler equations in $\mathbb{R}^2$, is linearly stable in self-similar coordinates with the natural scaling.
- [87] arXiv:2411.13402 (cross-list from gr-qc) [pdf, html, other]
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Title: Extraction of gravitational wave signals in realistic LISA dataEleonora Castelli, Quentin Baghi, John G. Baker, Jacob Slutsky, Jérôme Bobin, Nikolaos Karnesis, Antoine Petiteau, Orion Sauter, Peter Wass, William J. WeberComments: 28 pages, 14 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Methods for Astrophysics (astro-ph.IM); Data Analysis, Statistics and Probability (physics.data-an)
The Laser Interferometer Space Antenna (LISA) mission is being developed by ESA with NASA participation. As it has recently passed the Mission Adoption milestone, models of the instruments and noise performance are becoming more detailed, and likewise prototype data analyses must as well. Assumptions such as Gaussianity, Stationarity, and continuous data continuity are unrealistic, and must be replaced with physically motivated data simulations, and data analysis methods adapted to accommodate such likely imperfections. To this end, the LISA Data Challenges have produced datasets featuring time-varying and unequal constellation armlength, and measurement artifacts including data interruptions and instrumental transients. In this work, we assess the impact of these data artifacts on the inference of Galactic Binary and Massive Black Hole properties. Our analysis shows that the treatment of noise transients and gaps is necessary for effective parameter estimation. We find that straightforward mitigation techniques can significantly suppress artifacts, albeit leaving a non-negligible impact on aspects of the science.
- [88] arXiv:2411.13445 (cross-list from cond-mat.soft) [pdf, html, other]
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Title: Elucidating chirality transfer in liquid crystals of virusesJournal-ref: Nature Materials, Volume 23, September 2024, 1276-1282Subjects: Soft Condensed Matter (cond-mat.soft); Biological Physics (physics.bio-ph)
Chirality is ubiquitous in nature across all length scales, with major implications spanning the fields of biology, chemistry and physics to materials science. How chirality propagates from nanoscale building blocks to meso- and macroscopic helical structures remains an open issue. Here, working with a canonical system of filamentous viruses, we demonstrate that their self-assembly into chiral liquid crystal phases quantitatively results from the interplay between two main mechanisms of chirality transfer: electrostatic interactions from the helical charge patterns on the virus surface, and fluctuation-based helical deformations leading to viral backbone helicity. Our experimental and theoretical approach provides a comprehensive framework for deciphering how chirality is hierarchically and quantitatively propagated across spatial scales. Our work highlights the ways in which supramolecular helicity may arise from subtle chiral contributions of opposite handedness which either act cooperatively or competitively, thus accounting for the multiplicity of chiral behaviors observed for nearly identical molecular systems.
- [89] arXiv:2411.13463 (cross-list from cond-mat.soft) [pdf, html, other]
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Title: Dense Suspensions in Rotary ShearSubjects: Soft Condensed Matter (cond-mat.soft); Fluid Dynamics (physics.flu-dyn)
We introduce a novel unsteady shear protocol, which we name Rotary Shear (RS), where the flow and vorticity directions are continuously rotated around the velocity gradient direction by imposing two out-of-phase oscillatory shear (OS) in orthogonal directions. We perform numerical simulations of dense suspensions of rigid non-Brownian spherical particles at volume fractions ($\phi$) between 0.40 and 0.55 subject to this new RS protocol and compare to the classical OS protocol. We find that the suspension viscosity displays a similar non-monotonic response as the strain amplitude ($\gamma_0$) is increased: a minimum viscosity is found at an intermediate, volume-fraction dependent strain amplitude. However, the suspension dynamics is different in the new protocol. Unlike the OS protocol, suspensions under RS do not show self-adsorbing states at any $\gamma_0$ and do not undergo the reversible-irreversible transition: the stroboscropic particle dynamics are always diffusive, which we attribute to the fact that the RS protocol is irreversible. To validate this hypothesis, we introduce a reversible-RS (RRS) protocol, a combination of RS and OS, where we rotate the shear direction (as in RS) until it is instantaneously reversed (as in OS), and find the resulting rheology and dynamics to be closer to OS. Detailed microstructure analysis shows that both the OS and RRS protocols result in a contact-free, isotropic to an in-contact, anisotropic microstructure at the dynamically reversible-to-irreversible transition. The RS protocol does not render such a transition, and the dynamics remain diffusive with an in-contact, anisotropic microstructure for all strain amplitudes.
- [90] arXiv:2411.13496 (cross-list from cs.LG) [pdf, html, other]
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Title: Advancing Heatwave Forecasting via Distribution Informed-Graph Neural Networks (DI-GNNs): Integrating Extreme Value Theory with GNNsFarrukh A. Chishtie, Dominique Brunet, Rachel H. White, Daniel Michelson, Jing Jiang, Vicky Lucas, Emily Ruboonga, Sayana Imaash, Melissa Westland, Timothy Chui, Rana Usman Ali, Mujtaba Hassan, Roland Stull, David HudakComments: 23 pages, 13 figures, pdf formatSubjects: Machine Learning (cs.LG); Atmospheric and Oceanic Physics (physics.ao-ph); Physics and Society (physics.soc-ph)
Heatwaves, prolonged periods of extreme heat, have intensified in frequency and severity due to climate change, posing substantial risks to public health, ecosystems, and infrastructure. Despite advancements in Machine Learning (ML) modeling, accurate heatwave forecasting at weather scales (1--15 days) remains challenging due to the non-linear interactions between atmospheric drivers and the rarity of these extreme events. Traditional models relying on heuristic feature engineering often fail to generalize across diverse climates and capture the complexities of heatwave dynamics. This study introduces the Distribution-Informed Graph Neural Network (DI-GNN), a novel framework that integrates principles from Extreme Value Theory (EVT) into the graph neural network architecture. DI-GNN incorporates Generalized Pareto Distribution (GPD)-derived descriptors into the feature space, adjacency matrix, and loss function to enhance its sensitivity to rare heatwave occurrences. By prioritizing the tails of climatic distributions, DI-GNN addresses the limitations of existing methods, particularly in imbalanced datasets where traditional metrics like accuracy are misleading. Empirical evaluations using weather station data from British Columbia, Canada, demonstrate the superior performance of DI-GNN compared to baseline models. DI-GNN achieved significant improvements in balanced accuracy, recall, and precision, with high AUC and average precision scores, reflecting its robustness in distinguishing heatwave events.
- [91] arXiv:2411.13517 (cross-list from cs.SI) [pdf, html, other]
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Title: Understanding the Personal Networks of People Experiencing Homelessness in King County, WA with aggregate Relational DataSubjects: Social and Information Networks (cs.SI); Physics and Society (physics.soc-ph)
The social networks of people experiencing homelessness are an understudied but vital aspect of their lives, offering access to information, support, and safety. In 2023, the U.S. Department of Housing and Urban Development reported 653,100 people experiencing homelessness on any given night -- a 23% rise since 2022, though likely an undercount. This paper examines a unique three-year dataset (2022-2024) of survey responses from over 3,000 unhoused individuals in King County, WA, collected via network-based sampling methods to estimate the unsheltered population. Our study analyzes the networks of the unsheltered population, focusing on acquaintance, close friendship, kinship, and peer referral networks. Findings reveal a decline in social connectivity over time. The average number of acquaintances dropped from 80 in 2023 to 40 in 2024. Close friendship levels remained stable at 2.5, but given the growth in the homeless population, this suggests decreased network connectivity. Kinship networks expanded, indicating that more family members of unhoused individuals are also experiencing homelessness. These trends suggest increasing social disconnection, possibly driven by displacement and a rise in newly homeless individuals. The growing isolation may reduce opportunities for information sharing and mutual support. However, the increased reliance on family networks highlights the shifting dynamics of social support within this community. This research underscores the need for policies fostering social connections and community building, such as reducing displacement and providing spaces for congregation, to counter the growing anomie among unhoused populations.
- [92] arXiv:2411.13531 (cross-list from math.NA) [pdf, html, other]
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Title: Space-time model reduction in the frequency domainComments: 34 pages, 11 figuresSubjects: Numerical Analysis (math.NA); Fluid Dynamics (physics.flu-dyn)
Most model reduction methods are space-only in that they reduce the spatial dimension of the solution but not the temporal one. These methods integrate an encoding of the state of the nonlinear dynamical system forward in time. We propose a space-time method -- one that solves a system of algebraic equations for the encoding of the trajectory, i.e., the solution on a time interval $[0,T]$. The benefit of this approach is that with the same total number of degrees of freedom, a space-time encoding can leverage spatiotemporal correlations to represent the trajectory far more accurately than a space-only one. We use spectral proper orthogonal decomposition (SPOD) modes, a spatial basis at each temporal frequency tailored to the structures that appear at that frequency, to represent the trajectory. These modes have a number of properties that make them an ideal choice for space-time model reduction. We derive an algebraic system involving the SPOD coefficients that represent the solution, as well as the initial condition and the forcing. The online phase of the method consists of solving this system for the SPOD coefficients given the initial condition and forcing. We test the model on a Ginzburg-Landau system, a $1 + 1$ dimensional nonlinear PDE. We find that the proposed method is $\sim 2$ orders of magnitude more accurate than POD-Galerkin at the same number of modes and CPU time for all of our tests. In fact, the method is substantially more accurate even than the projection of the solution onto the POD modes, which is a lower bound for the error of any space-only Petrov-Galerkin method.
- [93] arXiv:2411.13532 (cross-list from cs.DC) [pdf, other]
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Title: A Distributed-memory Tridiagonal Solver Based on a Specialised Data Structure Optimised for CPU and GPU ArchitecturesComments: 42 pages, 13 figures, 6 tablesSubjects: Distributed, Parallel, and Cluster Computing (cs.DC); Computational Physics (physics.comp-ph)
Various numerical methods used for solving partial differential equations (PDE) result in tridiagonal systems. Solving tridiagonal systems on distributed-memory environments is not straightforward, and often requires significant amount of communication. In this article, we present a novel distributed-memory tridiagonal solver algorithm, DistD2-TDS, based on a specialised data structure. DistD2-TDS algorithm takes advantage of the diagonal dominance in tridiagonal systems to reduce the communications in distributed-memory environments. The underlying data structure plays a crucial role for the performance of the algorithm. First, the data structure improves data localities and makes it possible to minimise data movements via cache blocking and kernel fusion strategies. Second, data continuity enables a contiguous data access pattern and results in efficient utilisation of the available memory bandwidth. Finally, the data layout supports vectorisation on CPUs and thread level parallelisation on GPUs for improved performance. In order to demonstrate the robustness of the algorithm, we implemented and benchmarked the algorithm on CPUs and GPUs. We investigated the single rank performance and compared against existing algorithms. Furthermore, we analysed the strong scaling of the implementation up to 384 NVIDIA H100 GPUs and up to 8192 AMD EPYC 7742 CPUs. Finally, we demonstrated a practical use case of the algorithm by using compact finite difference schemes to solve a 3D non-linear PDE. The results demonstrate that DistD2 algorithm can sustain around 66% of the theoretical peak bandwidth at scale on CPU and GPU based supercomputers.
Cross submissions (showing 30 of 30 entries)
- [94] arXiv:2210.10623 (replaced) [pdf, html, other]
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Title: Names from Greek Myth in Fundamental PhysicsComments: 12 pages + bibliography + 2 indices; suggestions for more entries welcome; v3 update: ~10 new names added, future updates in this https URLSubjects: Popular Physics (physics.pop-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph); Physics Education (physics.ed-ph)
Greek mythology supplies fundamental physics with the names of numerous (100+) experiments, machines, codes, and phenomena. I present the central narrative of Greek mythos via these names. Hyperlinks are provided for their physics counterparts, and the names are collected in myth- and physics-themed indices.
- [95] arXiv:2303.05287 (replaced) [pdf, html, other]
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Title: The epidemiological footprint of contact structures in models with two levels of mixingVincent Bansaye (CMAP, MERGE), François Deslandes (MaIAGE), Madeleine Kubasch (CMAP, MaIAGE, MERGE), Elisabeta Vergu (MaIAGE)Comments: Adding acknowledgementsSubjects: Physics and Society (physics.soc-ph); Populations and Evolution (q-bio.PE)
Models with several levels of mixing (households, workplaces), as well as various corresponding formulations for R0, have been proposed in the literature. However, little attention has been paid to the impact of the distribution of the population size within social structures, effect that can help plan effective interventions. We focus on the influence on the model outcomes of teleworking strategies, consisting in reshaping the distribution of workplace sizes. We consider a stochastic SIR model with two levels of mixing, accounting for a uniformly mixing general population, each individual belonging also to a household and a workplace. The variance of the workplace size distribution appears to be a good proxy for the impact of this distribution on key outcomes of the epidemic, such as epidemic size and peak. In particular, our findings suggest that strategies where the proportion of individuals teleworking depends sublinearly on the size of the workplace outperform the strategy with linear dependence. Besides, one drawback of the model with multiple levels of mixing is its complexity, raising interest in a reduced model. We propose a homogeneously mixing SIR ODE-based model, whose infection rate is chosen as to observe the growth rate of the initial model. This reduced model yields a generally satisfying approximation of the epidemic. These results, robust to various changes in model structure, are very promising from the perspective of implementing effective strategies based on social distancing of specific contacts. Furthermore, they contribute to the effort of building relevant approximations of individual based models at intermediate scales.
- [96] arXiv:2308.08132 (replaced) [pdf, html, other]
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Title: Accuracy of Kohn-Sham density functional theory for warm- and hot-dense matter equation of stateComments: 9 pages, 1 figure, 3 tablesSubjects: Computational Physics (physics.comp-ph); Plasma Physics (physics.plasm-ph)
We study the accuracy of Kohn-Sham density functional theory (DFT) for warm- and hot-dense matter (WDM and HDM). Specifically, considering a wide range of systems, we perform accurate ab initio molecular dynamics simulations with temperature-independent local/semilocal density functionals to determine the equations of state at compression ratios of 3x--7x and temperatures near 1 MK. We find very good agreement with path integral Monte Carlo benchmarks, while having significantly smaller error bars and smoother data, demonstrating the accuracy of DFT for the study of WDM and HDM at such conditions. In addition, using a $\Delta$-machine learned force field scheme, we confirm that the DFT results are insensitive to the choice of exchange-correlation functional, whether local, semilocal, or nonlocal.
- [97] arXiv:2401.09920 (replaced) [pdf, html, other]
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Title: On the determination of the interaction time of GeV neutrinos in large argon gas TPCsA. Saá-Hernández, D. González-Díaz, J. Martín-Albo, M. Tuzi, P. Amedo, J. Baldonedo, C. Benítez, S. Bounasser, E. Casarejos, J. Collazo, A. Fernández-Prieto, D. J. Fernández-Posada, R. Hafeji, S. Leardini, D. Rodas-Rodríguez, A.L. Saborido, A. Segade, A. SlaterSubjects: Instrumentation and Detectors (physics.ins-det)
Next-generation megawatt-scale neutrino beams open the way to studying neutrino-nucleus scattering using gaseous targets for the first time. This represents an opportunity to improve the knowledge of neutrino cross sections in the energy region between hundreds of MeV and a few GeV, of interest for the upcoming generation of long-baseline neutrino oscillation experiments. The challenge is to accurately track and (especially) time the particles produced in neutrino interactions in large and seamless volumes down to few-MeV energies. We propose to accomplish this through an optically-read time projection chamber (TPC) filled with high-pressure argon and equipped with both tracking and timing functions. In this work, we present a detailed study of the time-tagging capabilities of such a device, based on end-to-end optical simulations that include the effect of photon propagation, photosensor response, dark count rate and pulse reconstruction. We show that the neutrino interaction time can be reconstructed from the primary scintillation signal with a precision in the range of 1-2.5 ns ($\sigma$) for point-like deposits with energies down to 5 MeV. A similar response is observed for minimum-ionizing particle tracks extending over lengths of a few meters. A discussion on previous limitations towards such a detection technology, and how they can be realistically overcome in the near future thanks to recent developments in the field, is presented. The performance demonstrated in our analysis seems to be well within reach of next-generation neutrino-oscillation experiments, through the instrumentation of the proposed TPC with conventional reflective materials and a silicon photomultiplier array behind a transparent cathode.
- [98] arXiv:2403.19311 (replaced) [pdf, html, other]
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Title: Pseudounitary Floquet scattering matrix for wave-front shaping in time-periodic photonic mediaComments: Final version with restriction to reciprocal scattering systems removedJournal-ref: Phys. Rev. A 110, 053515 (2024)Subjects: Optics (physics.optics)
The physics of waves in time-varying media provides numerous opportunities for wave control that are unattainable with static media. In particular, Floquet systems with a periodic time modulation are currently of considerable interest. Here, we demonstrate how the scattering properties of a finite Floquet medium can be correctly described by a static Floquet scattering matrix, which satisfies a pseudounitary relation. This algebraic property is a consequence of the conservation of wave action for which we formulate here a continuity equation. Using this Floquet scattering matrix, we further demonstrate how it can be used to transfer concepts for wavefront-shaping based on the Wigner-Smith operator from static to Floquet systems. The eigenstates of the corresponding Floquet Wigner-Smith matrix are shown to be light pulses that are optimally shaped in both their spatial and temporal degrees of freedom for the optical micromanipulation of time-varying media.
- [99] arXiv:2405.20751 (replaced) [pdf, other]
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Title: Linear models of strip-type roughnessSubjects: Fluid Dynamics (physics.flu-dyn)
Prandtl's secondary flows of the second kind generated by laterally-varying roughness are studied using the linearised Reynolds-Averaged Navier-Stokes approach proposed in Zampino et al (2022). The momentum equations are coupled to the Spalart-Allmaras model while the roughness is captured by adapting established strategies for homogeneous roughness to heterogeneous surfaces. Linearisation of the governing equations yields a framework that enables a rapid exploration of the parameter space associated with heterogeneous surfaces, in the limiting case of small spanwise variations of the roughness properties. Channel flow is considered, with longitudinal high and low roughness strips arranged symmetrically. By varying the strip width, it is found that linear mechanisms play a dominant role in determining the size and intensity of secondary flows. In this setting, secondary flows may be interpreted as the time-averaged output response of the turbulent mean flow subjected to a steady forcing produced by the wall heterogeneity. In fact, the linear model predicts that secondary flows are most intense when the strip width is about 0.7 times the half-channel height, in excellent agreement with available data. Furthermore, a unified framework to analyse combinations of heterogeneous roughness properties and laterally-varying topographies, common in applications, is discussed. Noting that the framework assumes small spanwise variations of the surface properties, two separate secondary-flow inducing source mechanisms are identified, i.e. the lateral variation of the virtual origin from which the turbulent structure develops and the lateral variation of the streamwise velocity slip, capturing the acceleration/deceleration perceived by the bulk flow over troughs and crests of non-planar topographies.
- [100] arXiv:2405.20943 (replaced) [pdf, html, other]
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Title: Optimizing EPR pulses for broadband excitation and refocusingComments: 12 pages, 8 figuresSubjects: Chemical Physics (physics.chem-ph); Quantum Physics (quant-ph)
In this paper, we numerically optimize broadband pulse shapes that maximize Hahn echo amplitudes. Pulses are parameterized as neural networks (NN), nonlinear amplitude limited Fourier series (FS), and discrete time series (DT). These are compared to an optimized choice of the conventional hyperbolic secant (HS) pulse shape. A power constraint is included, as are realistic shape distortions due to power amplifier nonlinearity and the transfer function of the microwave resonator. We find that the NN, FS, and DT parameterizations perform equivalently, offer improvements over the best HS pulses, and contain a large number of equivalent optimal solutions, implying the flexibility to include further constraints or optimization goals in future designs.
- [101] arXiv:2406.02719 (replaced) [pdf, other]
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Title: Analysis of the blowout plasma wakefields produced by drive beams with elliptical symmetryP. Manwani, Y. Kang, J. Mann, B. Naranjo, G. Andonian, J. B. Rosenzweig (Department of Physics and Astronomy, UCLA, Los Angeles, California, USA)Comments: 8 pages, 4 figuresSubjects: Accelerator Physics (physics.acc-ph); Plasma Physics (physics.plasm-ph)
In the underdense (blowout) regime of plasma wakefield acceleration (PWFA), the particle beam is denser than the plasma. Under these conditions, the plasma electrons are nearly completely rarefacted from the beam channel, resulting in a nominally uniform ion column. Extensive investigations of this interaction assuming axisymmetry have been undertaken. However, the plasma blowout produced by a transversely asymmetric driver possesses quite different characteristics. They create an asymmetric plasma rarefaction region (bubble) which leads to asymmetric focusing in the two transverse planes. This is also accompanied by an undesired non-uniform accelerating gradient. The asymmetric blowout cross-section is found through simulation to be elliptical, and treating it as such permits a simple extension of the symmetric theory. In particular, focusing fields linear in both transverse directions exist in the bubble. The form of the wake potential and the concomitant matching conditions in this elliptical cavity are discussed in this paper. We also discuss bubble boundary estimation in the long driver limit and applications of the asymmetric features of the wakefield.
- [102] arXiv:2406.13054 (replaced) [pdf, html, other]
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Title: Characterization of a radiation detector based on opaque water-based liquid scintillatorComments: 41 pages, 15 figuresSubjects: Instrumentation and Detectors (physics.ins-det)
We present the characterization of a novel radiation detector based on an opaque water-based liquid scintillator. Opaque scintillators, also known as LiquidO, are made to be highly scattering, such that the scintillation light is effectively confined, and read out through wavelength-shifting fibers. The 1-liter, 32-channel prototype demonstrates the capability for both spectroscopy and topological reconstruction of point-like events. The design, construction, and evaluation of the detector are described, including modeling of the scintillation liquid optical properties and the detector's response to gamma rays of several energies. A mean position reconstruction error of 4.4 mm for 1.6 MeV-equivalent events and 7.4 mm for 0.8 MeV-equivalent events is demonstrated using a simple reconstruction approach analogous to center-of-mass.
- [103] arXiv:2406.13789 (replaced) [pdf, html, other]
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Title: Death, Taxes, and Inequality. Can a Minimal Model Explain Real Economic Inequality?Comments: 12 pages, 5 figures, 1 tableSubjects: Physics and Society (physics.soc-ph); Computational Finance (q-fin.CP)
Income inequality and redistribution policies are modeled with a minimal, endogenous model of a simple foraging economy. Significant income inequalities emerge from the model for populations of equally capable individuals presented with equal opportunities. Stochastic income distributions from the model are compared to empirical data from actual economies. The impacts of redistribution policies on total wealth, income distributions, and inequality are shown to be similar for the empirical data and the model. These comparisons enable detailed determinations of population welfare beyond what is possible with total wealth and inequality metrics. I
- [104] arXiv:2407.12432 (replaced) [pdf, html, other]
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Title: Validation of the static forward Grad-Shafranov equilibrium solvers in FreeGSNKE and Fiesta using EFIT++ reconstructions from MAST-UK. Pentland, N.C. Amorisco, O. El-Zobaidi, S. Etches, A. Agnello, G. K. Holt, A. Ross, C. Vincent, J. Buchanan, S. J. P. Pamela, G. McArdle, L. Kogan, G. CunninghamSubjects: Plasma Physics (physics.plasm-ph); Computational Physics (physics.comp-ph)
A key aspect in the modelling of magnetohydrodynamic (MHD) equilibria in tokamak devices is having access to fast, accurate, and stable numerical simulation methods. There is an increasing demand for reliable methods that can be used to develop traditional or machine learning-based shape control feedback systems, optimise scenario designs, and integrate with other plasma edge or transport modelling codes. To handle such applications, these codes need to be flexible and, more importantly, they need to have been validated against both analytically known and real-world tokamak equilibria to ensure they are consistent and credible. In this paper, we are interested in solving the static forward Grad-Shafranov (GS) problem for free-boundary MHD equilibria. Our focus is on the validation of the static forward solver in the Python-based equilibrium code FreeGSNKE by solving equilibria from magnetics-only EFIT++ reconstructions of MAST-U shots. In addition, we also validate FreeGSNKE against equilibria simulated using the well-established MATLAB-based equilibrium code Fiesta. To do this, we develop a computational pipeline that allows one to load the same (a)symmetric MAST-U machine description into each solver, specify the required inputs (active/passive conductor currents, plasma profiles and coefficients, etc.) from EFIT++, and solve the GS equation for all available time slices across a shot. For a number of different MAST-U shots, we demonstrate that both FreeGSNKE and Fiesta can successfully reproduce various poloidal flux quantities and shape targets (e.g. midplane radii, magnetic axes, separatrices, X-points, and strikepoints) in agreement with EFIT++ calculations to a very high degree of accuracy. We also provide public access to the code/data required to load the MAST-U machine description in FreeGSNKE/Fiesta and reproduce the equilibria in the shots shown.
- [105] arXiv:2407.14160 (replaced) [pdf, html, other]
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Title: Angular momentum dependence in multiphoton ionization and attosecond time delaysSubjects: Atomic Physics (physics.atom-ph)
Attosecond ionization time-delays at photoelectron energies above typically 10 eV are usually interpreted using the so called asymptotic approximation as a sum of the atomic or molecular delays with a universal laser-induced contribution. Here, we employ a two-harmonic RABITT (Reconstruction of Attosecond Beating by Interference of Two-photon Transitions) configuration to isolate the multiphoton pathways and measure the ionization time delays as a function of the dressing field intensity. We show that the validity of the asymptotic theory can be extended to the threshold or to higher-order contributions by rigorously treating the angular-momentum dependence of the continuum-continuum transitions into universal and easily computable partial-wave-specific correction factors. Our asymptotic treatment is also valid for higher-order interfering amplitudes while significantly simplifying their evaluation and providing a transparent physical interpretation. The validity of the method for atomic and molecular targets in the vicinity of resonances, ionization thresholds, and for both the emission-integrated and angularly resolved signal is confirmed by comparison to ab initio calculations over a wide energy range.
- [106] arXiv:2408.03858 (replaced) [pdf, html, other]
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Title: Capturing Nonlinear Electron Dynamics with Fully Characterised Attosecond X-ray PulsesLars Funke, Markus Ilchen, Kristina Dingel, Tommaso Mazza, Terence Mullins, Thorsten Otto, Daniel E. Rivas, Sara Savio, Svitozar Serkez, Peter Walter, Niclas Wieland, Lasse Wülfing, Sadia Bari, Rebecca Boll, Markus Braune, Francesca Calegari, Alberto De Fanis, Winfried Decking, Andreas Duensing, Stefan Düsterer, Felix Egun, Arno Ehresmann, Benjamin Erk, Danilo Enoque Ferreira de Lima, Andreas Galler, Gianluca Geloni, Jan Grünert, Marc Guetg, Patrik Grychtol, Andreas Hans, Arne Held, Ruda Hindriksson, Till Jahnke, Joakim Laksman, Mats Larsson, Jia Liu, Jon P. Marangos, Lutz Marder, David Meier, Michael Meyer, Najmeh Mirian, Christian Ott, Christopher Passow, Thomas Pfeifer, Patrick Rupprecht, Albert Schletter, Philipp Schmidt, Frank Scholz, Simon Schott, Evgeny Schneidmiller, Bernhard Sick, Kai Tiedtke, Sergey Usenko, Vincent Wanie, Markus Wurzer, Mikhail Yurkov, Vitali Zhaunerchyk, Wolfram HelmlSubjects: Optics (physics.optics); Atomic Physics (physics.atom-ph)
Attosecond X-ray pulses are the key to studying electron dynamics at their natural timescale in specifically targeted electronic states. They promise to build the conceptual bridge between physical and chemical photo-reaction processes. Free-electron lasers (FELs) have demonstrated their capability of generating intense attosecond X-ray pulses. The use of SASE-based FELs for time-resolving experiments and investigations of nonlinear X-ray absorption mechanisms, however, necessitates their full pulse-to-pulse characterisation which remains a cutting-edge challenge. We have characterised X-ray pulses with durations of down to 600 attoseconds and peak powers up to 200 GW at ~1 keV photon energy via angular streaking at the Small Quantum Systems instrument of the European XFEL in Germany. As a direct application, we present results of nonlinear X-ray--matter interaction via time-resolved electron spectroscopy on a transient system, observing single- and double-core-hole generation in neon atoms. Using the derived temporal information about each single X-ray pulse, we reveal an otherwise hidden peak-intensity dependence of the probability for formation of double-core vacancies in neon after primary K-shell ionisation. Our results advance the field of attosecond science with highly intense and fully characterised X-ray pulses to the state-specific investigation of electronic motion in non-stationary media.
- [107] arXiv:2408.07306 (replaced) [pdf, other]
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Title: Deep-sub-cycle ultrafast optical pulsesSubjects: Optics (physics.optics)
Sub-cycle optical pulse is of great importance for ultrafast science and technology. While a narrower pulse can offer a higher temporal resolution, so far the pulse width has not reached the limit of half an optical cycle. Here we propose to break the half-cycle limit via inverse Compton scattering in a deep-subwavelength-confined infrared or THz optical driving field, which can be converted into a deep-sub-cycle (i.e., less than half a cycle) ultrafast pulse by relativistic electrons passing through. Quantitatively, by using a deep-subwavelength-confined 0.4-THz 1-ps pulsed driving field and a 3-MeV 1-fs electron bunch, we obtain a $\sim$ 0.1-cycle femtosecond pulse with a peak frequency of $\sim$ 26 THz ($\sim$ 38 fs in optical cycle) and a pulse width of $\sim$ 3.6 fs; with the same driving field and a 30-MeV 50-as electron bunch, we obtain a 0.17-cycle attosecond pulse with a peak frequency of $\sim$ 2.0 PHz ($\sim$ 500 as in optical cycle) and a pulse width of $\sim$ 86 as. Below the optical damage threshold of the field-confinement material, the single-pulse photon number can exceed $10^6$. Such pulses may open opportunities for studying light-matter interaction on the deep-sub-cycle level, and pave a way to unprecedented optical technology ranging from temporal super-resolution optical microscopy and spectroscopy to unconventional atom/molecule polarization and manipulation.
- [108] arXiv:2409.00154 (replaced) [pdf, html, other]
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Title: A note on the amplitude modulation phenomenon in non-canonical wall-bounded flowsComments: Accepted in the Physical Review Fluids, with 13 pages and 3 figuresSubjects: Fluid Dynamics (physics.flu-dyn)
The amplitude modulation phenomena, defined originally by Mathis et al. (J. Fluid Mech., 628, 311-337; 2009), corresponds to a unique non-linear interaction between Reynolds number ($Re_{\tau}$) dependent large-scale motions and $Re_{\tau}$-invariant inner-scale motions observed in canonical wall-bounded flows. While similar non-linear interactions have been quantified previously in non-canonical wall-bounded flows, linking them solely to amplitude modulation is questionable due to the fact that each non-canonical effect is associated with distinct variations in the energies of both the large and inner scaled motions. This study revisits analysis of non-linear triadic interactions, with consideration to various non-canonical effects, by analyzing published hot-wire datasets acquired in the large Melbourne wind tunnel. It is found that triadic interactions, across the entire turbulence scale hierarchy, may become statistically significant with increasing intensity of non-canonical effects such as wall roughness, pressure gradients, and spanwise or wall-normal forcing (when compared relative to their respective canonical baseline cases at matched $Re_{\tau}$). This stands in contrast to previous observations made in canonical flows, where only the interaction between inner scales and inertia-dominated large scales was considered dynamically significant for increasing $Re_{\tau}$. The implications of these findings are discussed for near-wall flow prediction models in non-canonical flows, which should take into account \emph{all} non-linear interactions coexisting in wall-bounded flows.
- [109] arXiv:2409.08423 (replaced) [pdf, other]
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Title: Leveraging Multiplexed Metasurfaces for Multi-Task Learning with All-Optical Diffractive ProcessorsComments: 17 pages, 6 figuresSubjects: Optics (physics.optics); Applied Physics (physics.app-ph)
Diffractive Neural Networks (DNNs) leverage the power of light to enhance computational performance in machine learning, offering a pathway to high-speed, low-energy, and large-scale neural information processing. However, most existing DNN architectures are optimized for single tasks and thus lack the flexibility required for the simultaneous execution of multiple tasks within a unified artificial intelligence platform. In this work, we utilize the polarization and wavelength degrees of freedom of light to achieve optical multi-task identification using the MNIST, FMNIST, and KMNIST datasets. Employing bilayer cascaded metasurfaces, we construct dual-channel DNNs capable of simultaneously classifying two tasks, using polarization and wavelength multiplexing schemes through a meta-atom library. Numerical evaluations demonstrate performance accuracies comparable to those of individually trained single-channel, single-task DNNs. Extending this approach to three-task parallel recognition reveals an expected performance decline yet maintains satisfactory classification accuracies of greater than 80% for all tasks. We further introduce a novel end-to-end joint optimization framework to redesign the three-task classifier, demonstrating substantial improvements over the meta-atom library design and offering the potential for future multi-channel DNN designs. Our study could pave the way for the development of ultrathin, high-speed, and high-throughput optical neural computing systems.
- [110] arXiv:2409.10010 (replaced) [pdf, html, other]
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Title: Optical resonators constitute a universal spin simulatorSubjects: Optics (physics.optics); Disordered Systems and Neural Networks (cond-mat.dis-nn); Quantum Physics (quant-ph)
NP-hard computational problems can be efficiently recast as finding the ground state of an effective spin model. However, to date no convenient setup exists that can universally simulate all of them, even for a fixed problem size. Here we present such a setup, using a series of optical (or polaritonic) resonators arranged in a chain using the geometry recently introduced in [Phys. Rev. Applied 21, 024057 (2024)]. We demonstrate by example how the simulator solves Hamiltonian Cycle and traveling salesman problems, and show that it generalises to any NP-hard problem of arbitrary size.
- [111] arXiv:2409.19615 (replaced) [pdf, html, other]
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Title: The optimal structure of the MRPC detector for 0.511 MeV gamma based on Monte Carlo simulationSubjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)
The detailed simulation of the Multi-gap Resistive Plate Chambers (MRPCs) provides the performance characteristics of MRPCs with different numbers of gas gaps and gap thicknesses. This helps in optimizing the structure of MRPCs under specific conditions by balancing time resolution, detection efficiency, and other performance metrics. To obtain the optimal structure of MRPCs for 0.511 MeV gammas, a complete simulation framework for gamma detection by the MRPCs based on Geant4 and Magboltz software is described in this paper. The simulation shows how gamma interacts with MRPCs and the process of gas ionization, avalanche multiplication, and signal formation. The simulation results are in good agreement with the experimental results. By analyzing the time resolution and detection efficiency, the optimal structure of MRPCs for 0.511 MeV gammas is proposed.
- [112] arXiv:2410.09177 (replaced) [pdf, html, other]
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Title: From {\tt Ferminet} to PINN. Connections between neural network-based algorithms for high-dimensional Schr\"odinger HamiltonianSubjects: Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)
In this note, we establish some connections between standard (data-driven) neural network-based solvers for PDE and eigenvalue problems developed on one side in the applied mathematics and engineering communities (e.g. Deep-Ritz and Physics Informed Neural Networks (PINN)), and on the other side in quantum chemistry (e.g. Variational Monte Carlo algorithms, {\tt Ferminet} or {\tt Paulinet} following the pioneer work of {\it Carleo et. al}. In particular, we re-formulate a PINN algorithm as a {\it fitting} problem with data corresponding to the solution to a standard Diffusion Monte Carlo algorithm initialized thanks to neural network-based Variational Monte Carlo. Connections at the level of the optimization algorithms are also established.
- [113] arXiv:2410.11807 (replaced) [pdf, html, other]
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Title: Regional Ocean Forecasting with Hierarchical Graph Neural NetworksComments: 28 pages, 35 figures. Accepted to the Tackling Climate Change with Machine Learning workshop at NeurIPS 2024Subjects: Atmospheric and Oceanic Physics (physics.ao-ph); Machine Learning (cs.LG)
Accurate ocean forecasting systems are vital for understanding marine dynamics, which play a crucial role in environmental management and climate adaptation strategies. Traditional numerical solvers, while effective, are computationally expensive and time-consuming. Recent advancements in machine learning have revolutionized weather forecasting, offering fast and energy-efficient alternatives. Building on these advancements, we introduce SeaCast, a neural network designed for high-resolution, medium-range ocean forecasting. SeaCast employs a graph-based framework to effectively handle the complex geometry of ocean grids and integrates external forcing data tailored to the regional ocean context. Our approach is validated through experiments at a high spatial resolution using the operational numerical model of the Mediterranean Sea provided by the Copernicus Marine Service, along with both numerical and data-driven atmospheric forcings.
- [114] arXiv:2410.23093 (replaced) [pdf, html, other]
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Title: Differentiable Conservative Radially Symmetric Fluid Simulations and Stellar Winds -- jf1uidsComments: 8 pages, 4 figures, accepted for the Machine Learning and the Physical Sciences workshop at NeurIPS 2024Subjects: Fluid Dynamics (physics.flu-dyn)
We present jf1uids, a one-dimensional fluid solver that can, by virtue of a geometric formulation of the Euler equations, model radially symmetric fluid problems in a conservative manner, i.e., without losing mass or energy. For spherical problems, such as ideal supernova explosions or stellar wind-blown bubble expansions, simulating only along a radial dimension drastically reduces compute and memory demands compared to a full three-dimensional method. This simplification also alleviates constraints on backpropagation through the solver. Written in JAX, jf1uids is a GPU-compatible and fully differentiable simulator. We demonstrate the advantages of this differentiable physics simulator by retrieving the wind's parameters for an adiabatic stellar wind expansion from the final fluid state using gradient descent. As part of a larger "stellar winds, cosmic rays and machine learning" research track, jf1uids serves as a solid foundation to be extended with additional physics modules, foremost cosmic rays and a neural-net powered gas-cooling surrogate and improved by higher order and more accurate numerical schemes. All code is available under this https URL.
- [115] arXiv:2411.04665 (replaced) [pdf, other]
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Title: PZT Optical MemristorsChenlei Li, Hongyan Yu, Tao Shu, Yueyang Zhang, Chengfeng Wen, Hengzhen Cao, Jin Xie, Hanwen Li, Zixu Xu, Gong Zhang, Zejie Yu, Huan Li, Liu Liu, Yaocheng Shi, Feng Qiu, Daoxin DaiSubjects: Optics (physics.optics); Applied Physics (physics.app-ph)
Optical memristors represent a monumental leap in the fusion of photonics and electronics, heralding a new era of applications from neuromorphic computing to artificial intelligence. However, current technologies are hindered by complex fabrication, limited endurance, high optical loss or low modulation depth. For the first time, we reveal optical non-volatility in thin-film Lead Zirconate Titanate (PZT) by electrically manipulating the ferroelectric domains to control the refractive index, providing a brand-new routine for optical memristors. The developed PZT optical memristors offer unprecedented advantages more than exceptional performance metrics like low loss of <2 dB/cm, high precision exceeding 6-bits, large modulation depth with an index change as large as 4.6x10-3. Additionally, these devices offer impressive stability, maintaining minimal wavelength variation for over three weeks and enduring more than 10,000 cycles, and require a mere 0.8 pJ of energy for non-volatile operation. The wafer-scale sol-gel fabrication process also ensures compatible with standardized mass fabrication processes and high scalability for photonic integration. Specially, these devices also demonstrate unique functional duality: setting above a threshold voltage enables non-volatile behaviors, below this threshold allows volatile high-speed optical modulation. This marks the first-ever optical memristor capable of performing high-speed (48 Gbps) and energy-efficient (450 fJ/bit) signal processing and non-volatile retention on a single platform, and is also the inaugural demonstration of scalable functional systems. The PZT optical memristors developed here facilitate the realization of novel paradigms for high-speed and energy-efficient optical interconnects, programmable PICs, quantum computing, neural networks, in-memory computing and brain-like architecture.
- [116] arXiv:2411.05576 (replaced) [pdf, other]
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Title: On-chip Moir\'e Optical Skyrmion Clusters with Nanoscale DynamicsSubjects: Optics (physics.optics); Applied Physics (physics.app-ph)
Skyrmions are topological defects belonging to nontrivial homotopy classes in particle theory, and are recognized as a suitable unit in the high-density, low-dissipation microelectronic devices in condensed matter physics. Their remarkably stable topology has recently been observed in electromagnetic waves. For the evanescent fields near a surface, this has been realized so far only for elementary optical skyrmions, with a fixed skyrmion number. Here we introduce the concept of moiré optical skyrmion clusters, where multi-skyrmions are nested to form a large optical skyrmion cluster that is either crystallized or quasi-crystallized as a consequence of the twisted nanostructures. The rapid inverting of optical skyrmion number is achieved in the imperfectly aligned composite nanostructures. This moiré optical skyrmion interaction mechanism is described by a lattice model. Further, the nucleation and collapse of optical skyrmion are studied, where their nanoscale dynamics are revealed with a tiny change of the twist angle. The sudden reversal of the on-chip skyrmion can serve as a precise beacon of the relative alignment deviation between twisted composite nanostructures.
- [117] arXiv:2411.08505 (replaced) [pdf, html, other]
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Title: LES-FGM modelling of non-premixed auto-igniting turbulent hydrogen flames including preferential diffusionSubjects: Fluid Dynamics (physics.flu-dyn)
Tabulated chemistry methods are a well-known strategy to efficiently store the flows thermochemical properties. In particular, the Flamelet-Generated Manifold (FGM) is a widely used technique that generates the database with a small number of control variables. In order to build such a manifold, these coordinates must be monotonic in space and time. However, the high diffusivity of hydrogen can prevent such requisite.
To avoid the non-monotonicity of control variables (the progress variable, in particular), one practical workaround is to perform the tabulation on zero-dimensional (0D) reactors rather than on one-dimensional (1D) flamelets. Various works already implemented and tested such 0D-based manifold, but mainly in the context of spray engines, where most of the composition is lean and information past the flammability limit is not relevant. The present work aims at investigating, for the first time, the applicability of a tabulation based on homogeneous reactors to study auto-igniting turbulent hydrogen jets.
It is shown that a combined use of homogeneous reactors at the lean side and an extrapolation with 1D flamelets on the richer side is required to capture both chemistry and diffusive effects accurately in pure hydrogen flames. Then, this manifold is coupled to Large-Eddy Simulation (LES) of three-dimensional turbulent mixing layers and evaluated against direct numerical simulation with detailed chemistry. Good agreement is found, in terms of both ignition delay and the following steady-state burning process. Further analyses are carried out on statistics and modelling. In particular, the sensitivity of the LES solution to filter width, turbulence-chemistry interaction and multidimensional flame effects is investigated to provide new relevant insights on modelling non-premixed auto-igniting turbulent hydrogen flames. - [118] arXiv:2411.10211 (replaced) [pdf, html, other]
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Title: Mixing High Harmonic Generation and X-ray Second Harmonic GenerationSubjects: Atomic Physics (physics.atom-ph); Optics (physics.optics)
We theoretically demonstrate the mixing of laser-driven high harmonic generation (HHG) and x-ray second harmonic generation (SHG) in gas-phase atoms, highlighting its potential as a powerful spectroscopic tool for studying atomic and molecular systems. Our simulations confirm the generation of HHG with x-ray SHG (HHG-XSHG) from atomic core electrons through the rescattering of electrons from x-ray two-photon excitation and subsequent tunneling ionization in an optical laser field. The resulting HHG-XSHG spectrum features a broadband multi-peak structure and a distinct spectral cutoff in the x-ray regime. These findings indicate that HHG-XSHG is a valuable technique for probing core-electron dynamics, generating attosecond x-ray pulses, and exploring nonlinear interactions, effectively merging laser-driven attosecond technology with nonlinear x-ray methodologies provided by x-ray free-electron lasers.
- [119] arXiv:2411.10306 (replaced) [pdf, html, other]
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Title: Demonstration of the minimal coupling of horizontal accelerations to rotations in a torsion balance suspended from three wiresSubjects: Instrumentation and Detectors (physics.ins-det)
The Cavendish torsion balance is the instrument of choice for measuring weak forces, such as gravity. Although torsion balances have extremely high sensitivity for measuring forces over ranges of a few cm and more, their dynamics make it difficult to extend this range to much less than fractions of mm. In particular forces such as the Casimir force are usually studied using atomic force microscopes. We present results of our studies of a simple torsion balance with a 3-wire suspension. This device should be able to maintain parallelism between flat plates of areas of a few $\sim\mathrm{cm^2}$ at separations of much less of 10's of $\mathrm{\mu m}$. In this paper we describe our experimental investigation into the coupling of ground tilt to the torsional rotation of the novel device. We show that, like the Cavendish torsion balance, the 3-wire torsion balance is highly insensitive to tilts. We also demonstrate that this tilt sensitivity is itself insensitive to shifts in the centre of mass position of the suspended mass. We discuss simple models of the 3-wire torsion balance that show that it is only the static wire lengths that determine the coupling of tilts and horizontal accelerations. We also discuss designs of torsion balances where sensitivity and noise rejection to tilts are optimised.
- [120] arXiv:2411.12057 (replaced) [pdf, html, other]
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Title: Revealing Structure and Symmetry of Nonlinearity in Natural and Engineering FlowsComments: BY and TC are equal contributors to this work and designated as co-first authorsSubjects: Fluid Dynamics (physics.flu-dyn); Chaotic Dynamics (nlin.CD)
Energy transfer across scales is fundamental in fluid dynamics, linking large-scale flow motions to small-scale turbulent structures in engineering and natural environments. Triadic interactions among three wave components form complex networks across scales, challenging understanding and model reduction. We introduce Triadic Orthogonal Decomposition (TOD), a method that identifies coherent flow structures optimally capturing spectral momentum transfer, quantifies their coupling and energy exchange in an energy budget bispectrum, and reveals the regions where they interact. TOD distinguishes three components--a momentum recipient, donor, and catalyst--and recovers laws governing pairwise, six-triad, and global triad conservation. Applied to unsteady cylinder wake and wind turbine wake data, TOD reveals networks of triadic interactions with forward and backward energy transfer across frequencies and scales.
- [121] arXiv:2411.12381 (replaced) [pdf, other]
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Title: Particle manipulations based on acoustic valley topological rainbow defect-state trappingDecai Wu, Bowei Wu, Tingfeng Ma, Shuanghuizhi Li, Iren Kuznetsova, Ilya Nedospasov, Boyue Su, Teng WangComments: There was an error in Figure 5Subjects: Classical Physics (physics.class-ph)
Acoustic microfluidic is an important technology in particle manipulations in biomedical analyses and detections. However, the particle-movement manipulations achieved by the standing surface acoustic wave is suitable for particles in a thin layer of fluids, however it is difficult to manipulate particles in deeper solutions due to the energy loss of surface acoustic waves. The traditional standing bulk wave method can realize the particle manipulation in deep solutions, but it cannot work properly for particle manipulation within a long distance due to the energy loss. In this work, the topological rainbow defect-state trapping is realized, the results show that an effect of point accumulation of acoustic pressure in the waveguide path exists, the position of maximum acoustic pressure can be adjusted flexibly by changing the frequency of the incident acoustic wave, based on which, long-distance movement and capture manipulations of particles in deep solution have been realized. The phenomenon presented in this work can provide a reliable method for manipulations of continuous long-distance particle movement and capture to meet the demand of multiple processing steps in biochemical analyses and detections. The experiment verification results will be presented in the near future.
- [122] arXiv:2411.12545 (replaced) [pdf, html, other]
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Title: When Theory Meets Experiment: What Does it Take to Accurately Predict $^1$H NMR Dipolar Relaxation Rates in Neat Liquid Water from Theory?Dietmar Paschek, Johanna Busch, Angel Mary Chiramel Tony, Ralf Ludwig, Anne Strate, Nore Stolte, Harald Forbert, Dominik MarxComments: 13 pages, 8 figures, added references, corrected authors list in metadataSubjects: Chemical Physics (physics.chem-ph); Soft Condensed Matter (cond-mat.soft)
In this contribution, we compute the $^1$H nuclear magnetic resonance (NMR) relaxation rate of liquid water at ambient conditions. We are using structural and dynamical information from Coupled Cluster Molecular Dynamics (CCMD) trajectories generated at CCSD(T) electronic structure accuracy while considering also nuclear quantum effects in addition to consulting information from X-ray and neutron scattering experiments. Our analysis is based on a recently presented computational framework for determining the frequency-dependent NMR dipole-dipole relaxation rate of spin $1/2$ nuclei from Molecular Dynamics (MD) simulations, which allows for an effective disentanglement of its structural and dynamical contributions, and is including a correction for finite-size effects inherent to MD simulations with periodic boundary conditions. A close to perfect agreement with experimental relaxation data is achieved if structural and dynamical informations from CCMD trajectories are considered including a re-balancing of the rotational and translational dynamics, according to the product of the self-diffusion coefficient and the reorientational correlation time of the H-H vector $D_0\times\tau_\mathrm{HH}$. The simulations show that this balance is significantly altered when nuclear quantum effects are taken into account. Our analysis suggests that the intermolecular and intramolecular contribution to the $^1$H NMR relaxation rate of liquid water are almost similar in magnitude, unlike to what was predicted earlier from classical MD simulations.
- [123] arXiv:2411.12562 (replaced) [pdf, html, other]
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Title: Refuting the Metaphysics of Wolfram and TegmarkComments: 18 pages, 5 figuresSubjects: History and Philosophy of Physics (physics.hist-ph)
Wolfram's hypergraph dynamics should replace outmoded models in physics. This should even more so be the case if experimental evidence for the theory is found (which I believe is probable). However, due to the breadth and depth of the theory, it may be difficult to produce experimental evidence which falsifies it. Some of Wolfram's personal work relating to his physics project is philosophical, and so mechanics of particular phenomena in the natural world can become a triviality or an aside. In other words, the general theory "casts a wide net", and it is the philosophical topics I will challenge. I find that Wolfram must adopt a radical epistemology through his so-called Observer Theory because there is no clear notion of Truth. Tegmark believes in an objective Truth, but I find its relation to the observer untenable, and the proof of his Mathematical Universe Hypothesis (MUH) is gematria. I argue both Wolfram and Tegmark conflate the inherent potential of mathematical truths with their instantiation or actuality in reality, making a similar error to that of the "so-called" Pythagoreans rebuked by Aristotle. Nonetheless, I believe that combinatorial structures of the kind used in the physics project (abstract rewriting, directed acyclic graphs) will be the future of physics as we know it.
- [124] arXiv:2211.13362 (replaced) [pdf, html, other]
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Title: Double-slit experiment revisitedComments: 15 pages Latex, 6 figures; v2 substantial extension and revision, extra co-authorSubjects: Quantum Physics (quant-ph); Computational Physics (physics.comp-ph); Popular Physics (physics.pop-ph)
The double-slit experiment is one of the quintessential quantum experiments. However, it tends to be overlooked that a theoretical account of this experiment requires the specification of the joint position and time distribution of detection at the screen, whose position marginal yields the famous interference pattern. The difficulty then arises what this distribution should be. While there exists a variety of proposals for a quantum mechanical time observable, there is no consensus about the right choice. Here, we consider Bohmian mechanics, which allows for a natural and practical approach to this problem. We simulate this distribution in the case of an initial Gaussian wave packet passing through a double-slit potential. We also consider a more challenging setup in which one of the slits is shut during flight. To experimentally probe the quantum nature of the time distribution, a sufficient longitudinal spread of the initial wave packet is required, which has not been achieved so far. Without sufficient spread, the temporal aspect of the distribution can be treated classically. We illustrate this for the case of the double-slit experiment with helium atoms by Kurtsiefer et al. [Nature 386, 150 (1997)], which reports the joint position and time distribution.
- [125] arXiv:2308.07298 (replaced) [pdf, html, other]
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Title: Accurate Eye Tracking from Dense 3D Surface Reconstructions using Single-Shot DeflectometrySubjects: Computer Vision and Pattern Recognition (cs.CV); Human-Computer Interaction (cs.HC); Optics (physics.optics)
Eye-tracking plays a crucial role in the development of virtual reality devices, neuroscience research, and psychology. Despite its significance in numerous applications, achieving an accurate, robust, and fast eye-tracking solution remains a considerable challenge for current state-of-the-art methods. While existing reflection-based techniques (e.g., "glint tracking") are considered to be very accurate, their performance is limited by their reliance on sparse 3D surface data acquired solely from the cornea surface. In this paper, we rethink the way how specular reflections can be used for eye tracking: We propose a novel method for accurate and fast evaluation of the gaze direction that exploits teachings from single-shot phase-measuring-deflectometry(PMD). In contrast to state-of-the-art reflection-based methods, our method acquires dense 3D surface information of both cornea and sclera within only one single camera frame (single-shot). For a typical measurement, we acquire $>3000 \times$ more surface reflection points ("glints") than conventional methods. We show the feasibility of our approach with experimentally evaluated gaze errors on a realistic model eye below only $0.12^\circ$. Moreover, we demonstrate quantitative measurements on real human eyes in vivo, reaching accuracy values between only $0.46^\circ$ and $0.97^\circ$.
- [126] arXiv:2310.17819 (replaced) [pdf, html, other]
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Title: Multiplexed Processing of Quantum Information Across an Ultra-wide Optical BandwidthSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
Protocols for processing of quantum information are the foundation of quantum technology, enabling to share secrets at a distance, teleport quantum states, and to implement quantum computation. While many protocols were realized, and even commercialized, the throughput and processing speed of current protocols is limited by the narrow electronic bandwidth of standard measurement devices (typically in the MHz-to-GHz range), which is orders-of-magnitude lower than the optical bandwidth of available quantum optical sources (10-100 THz), indicating that the bandwidth resource is dramatically underutilized in current quantum optical technology. We present a general concept of frequency multiplexed quantum channels and a set of methods to process quantum information efficiently across the available optical bandwidth. Using a broadband source of squeezed light, spectral manipulation methods and parametric homodyne detection, we are able to generate, process and measure all the channels in parallel, thereby harnessing the optical bandwidth for quantum information in an efficient manner. We exemplify the concept through two basic protocols: Multiplexed Continuous-Variable Quantum Key Distribution (CV-QKD) and multiplexed continuous-variable quantum teleportation. The multiplexed QKD protocol is demonstrated in a proof-of-principle experiment, where we successfully carry out QKD over 23 uncorrelated spectral channels, with capability to detect eavesdropping in any channel. These multiplexed methods (and similar) will enable to carry out quantum processing in parallel over hundreds of channels, potentially increasing the throughput of quantum protocols by orders of magnitude.
- [127] arXiv:2311.00888 (replaced) [pdf, other]
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Title: A robust shape model for blood vessels analysisSubjects: Computational Engineering, Finance, and Science (cs.CE); Medical Physics (physics.med-ph)
The availability of digital twins for the cardiovascular system will enable insightful computational tools both for research and clinical practice. This, however, demands robust and well defined models and methods for the different steps involved in the process. We present a vessel coordinate system (VCS) that enables the unanbiguous definition of locations in a vessel section, by adapting the idea of cylindrical coordinates to the vessel geometry. Using the VCS model, point correspondence can be defined among different samples of a cohort, allowing data transfer, quantitative comparison, shape coregistration or population analysis. Furthermore, the VCS model allows for the generation of specific meshes (e.g. cylindrical grids, ogrids) necessary for an accurate reconstruction of the geometries used in fluid simulations. We provide the technical details for coordinates computation and discuss the assumptions taken to guarantee that they are well defined. The VCS model is tested in a series of applications. We present a robust, low dimensional, patient specific vascular model and use it to study phenotype variability analysis of the thoracic aorta within a cohort of patients. Point correspondence is exploited to build an haemodynamics atlas of the aorta for the same cohort. The atlas originates from fluid simulations (Navier-Stokes with Finite Volume Method) conducted using OpenFOAMv10. We finally present a relevant discussion on the VCS model, which covers its impact in important areas such as shape modeling and computer fluids dynamics (CFD).
- [128] arXiv:2401.17372 (replaced) [pdf, html, other]
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Title: Optically-Trapped Nanodiamond-Relaxometry Detection of Nanomolar Paramagnetic Spins in Aqueous EnvironmentsShiva Iyer, Changyu Yao, Olivia Lazorik, Md Shakil Bin Kashem, Pengyun Wang, Gianna Glenn, Michael Mohs, Yinyao Shi, Michael Mansour, Erik Henriksen, Kater Murch, Shankar Mukherji, Chong ZuComments: 7 pages, 3 figuresSubjects: Quantum Physics (quant-ph); Biological Physics (physics.bio-ph)
Probing electrical and magnetic properties in aqueous environments remains a frontier challenge in nanoscale sensing. Our inability to do so with quantitative accuracy imposes severe limitations, for example, on our understanding of the ionic environments in a diverse array of systems, ranging from novel materials to the living cell. The Nitrogen-Vacancy (NV) center in fluorescent nanodiamonds (FNDs) has emerged as a good candidate to sense temperature, pH, and the concentration of paramagnetic species at the nanoscale, but comes with several hurdles such as particle-to-particle variation which render calibrated measurements difficult, and the challenge to tightly confine and precisely position sensors in aqueous environment. To address this, we demonstrate relaxometry with NV centers within optically-trapped FNDs. In a proof of principle experiment, we show that optically-trapped FNDs enable highly reproducible nanomolar sensitivity to the paramagnetic ion, (\mathrm{Gd}^{3+}). We capture the three distinct phases of our experimental data by devising a model analogous to nanoscale Langmuir adsorption combined with spin coherence dynamics. Our work provides a basis for routes to sense free paramagnetic ions and molecules in biologically relevant conditions.
- [129] arXiv:2402.19123 (replaced) [pdf, html, other]
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Title: Sensing atomic superfluid rotation beyond the standard quantum limitComments: 16 pages, 13 figuresJournal-ref: Phys. Rev. A 110, 053514 (2024)Subjects: Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas); Statistical Mechanics (cond-mat.stat-mech); Optics (physics.optics)
Atomic superfluids formed using Bose-Einstein condensates (BECs) in a ring trap are currently being investigated in the context of superfluid hydrodynamics, quantum sensing and matter-wave interferometry. The characterization of the rotational properties of such superfluids is important, but can presently only be performed by using optical absorption imaging, which completely destroys the condensate. Recent studies have proposed coupling the ring BEC to optical cavity modes carrying orbital angular momentum to make minimally destructive measurements of the condensate rotation. The sensitivity of these proposals, however, is bounded below by the standard quantum limit set by the combination of laser shot noise and radiation pressure noise. In this work, we provide a theoretical framework that exploits the fact that the interaction between the scattered modes of the condensate and the light reduces to effective optomechanical equations of motion. We present a detailed theoretical analysis to demonstrate that the use of squeezed light and backaction evasion techniques allows the angular momentum of the condensate to be sensed with noise well below the standard quantum limit. Our proposal is relevant to atomtronics, quantum sensing and quantum information.
- [130] arXiv:2402.19247 (replaced) [pdf, html, other]
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Title: Noisy intermediate-scale quantum simulation of the one-dimensional wave equationLewis Wright, Conor Mc Keever, Jeremy T. First, Rory Johnston, Jeremy Tillay, Skylar Chaney, Matthias Rosenkranz, Michael LubaschComments: 11 pages, 8 figures, 1 tableJournal-ref: Phys. Rev. Research 6, 043169 (2024)Subjects: Quantum Physics (quant-ph); Mathematical Physics (math-ph); Applied Physics (physics.app-ph); Classical Physics (physics.class-ph); Computational Physics (physics.comp-ph)
We design and implement quantum circuits for the simulation of the one-dimensional wave equation on the Quantinuum H1-1 quantum computer. The circuit depth of our approach scales as $O(n^{2})$ for $n$ qubits representing the solution on $2^{n}$ grid points, and leads to infidelities of $O(2^{-4n} t^{2})$ for simulation time $t$ assuming smooth initial conditions. By varying the qubit count we study the interplay between the algorithmic and physical gate errors to identify the optimal working point of minimum total error. Our approach to simulating the wave equation can be used with appropriate state preparation algorithms across different quantum processors and serve as an application-oriented benchmark.
- [131] arXiv:2403.06795 (replaced) [pdf, html, other]
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Title: Exploring noisy Jeffery orbits: A combined Fokker-Planck and Langevin analysis in 2D and 3DComments: 16 pages, 13 Postscript figuresJournal-ref: Physical Review E, 110 (2024) 044143Subjects: Soft Condensed Matter (cond-mat.soft); Fluid Dynamics (physics.flu-dyn)
The behavior of non-spherical particles in a shear-flow is of significant practical and theoretical interest. These systems have been the object of numerous investigations since the pioneering work of Jeffery a century ago. His eponymous orbits describe the deterministic motion of an isolated, rod-like particle in a shear flow. Subsequently, the effect of adding noise was investigated. The theory has been applied to colloidal particles, macromolecules, anisometric granular particles and most recently to microswimmers, for example bacteria. We study the Jeffery orbits of elongated particles subject to noise using Langevin simulations and a Fokker-Planck equation. We extend the analytical solution for infinitely thin needles ($\beta=1$) obtained by Doi and Edwards to particles with arbitrary shape factor ($0\le \beta\le 1$) and validate the theory by comparing it with simulations. We examine the rotation of the particle around the vorticity axis and study the orientational order matrix. We use the latter to obtain scalar order parameters $s$ and $r$ describing nematic ordering and biaxiality from the orientational distribution function. The value of $s$ (nematic ordering) increases monotonically with increasing Péclet number, while $r$ (measure of biaxiality) displays a maximum value. From perturbation theory we obtain simple expressions that provide accurate descriptions at low noise (or large Péclet numbers). We also examine the orientational distribution in the v-grad v plane and in the perpendicular direction. Finally we present the solution of the Fokker-Planck equation for a strictly two-dimensional (2D) system. For the same noise amplitude the average rotation speed of the particle in 3D is larger than in 2D.
- [132] arXiv:2405.21065 (replaced) [pdf, html, other]
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Title: Single-beam grating-chip 3D and 1D optical latticesComments: 7 pages, 3 figures, Supplementary Material, to appear in Phys. Rev. LettSubjects: Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph)
Ultracold atoms are crucial for unlocking truly precise and accurate quantum metrology, and provide an essential platform for quantum computing, communication and memories. One of the largest ongoing challenges is the miniaturization of these quantum devices. Here, we show that the typically macroscopic optical lattice architecture at the heart of many ultra-precise quantum technologies can be realized with a single input laser beam on the same diffractive chip already used to create the ultracold atoms. Moreover, this inherently ultra-stable platform enables access to a plethora of new lattice dimensionalities and geometries, ideally suited for the design of high-accuracy, portable quantum devices.
- [133] arXiv:2406.01865 (replaced) [pdf, html, other]
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Title: The influence of active agent motility on SIRS epidemiological dynamicsComments: 26 pages, 20 figuresSubjects: Soft Condensed Matter (cond-mat.soft); Cellular Automata and Lattice Gases (nlin.CG); Physics and Society (physics.soc-ph)
Active Brownian disks moving in two dimensions that exchange information about their internal state stochastically are chosen to model epidemic spread in a self-propelled population of agents under the susceptible-infected-recovered-susceptible (SIRS) framework. The state of infection of an agent, or disk, governs its self-propulsion speed; consequently, the activity of the agents in the system varies in time. Two different protocols (one-to-one and one-to-many) are considered for the transmission of disease from the infected to susceptible populations. The effectiveness of the two protocols are practically identical at high values of the infection transmission rate. The one-to-many protocol, however, outperforms the one-to-one protocol at lower values of the infection transmission rate. Salient features of the macroscopic SIRS model are revisited, and compared to predictions from the agent-based model. Lastly, the motility induced phase separation in a population of such agents with a fluctuating fraction of active disks is found to be well-described by theories governing phase separation in a mixture of active and passive particles with a constant fraction of passive disks.
- [134] arXiv:2406.05324 (replaced) [pdf, html, other]
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Title: Bipartite reweight-annealing algorithm to extract large-scale data of entanglement entropy and its derivative in high precisionSubjects: Strongly Correlated Electrons (cond-mat.str-el); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics - Theory (hep-th); Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)
We propose a quantum Monte Carlo (QMC) scheme able to extract large-scale data of entanglement entropy (EE) and its derivative with high precision and low technical barrier. We avoid directly computing the overlap of two partition functions within different spacetime manifolds and instead obtain them separately via reweight-annealing scheme. The incremental process can be designed along the path of real physical parameters in this frame, and all intermediates are EEs of corresponding parameters, so the algorithm efficiency is improved by more than $10^4$ of times. The calculation of EE becomes much cheaper and simpler. It opens a way to numerically detect the novel phases and phase transitions by scanning EE in a wide parameter-region in two and higher dimensional systems. We then show the feasibility of using EE and its derivative to find phase transition points and to probe novel phases.
- [135] arXiv:2406.16622 (replaced) [pdf, html, other]
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Title: Simultaneous Generation of Quantum Frequency Combs across Distinct Modal Families in a Single $Si_3 N_4$ Whispering Gallery Mode ResonatorComments: 20 pages, 9 figuresSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
Quantum frequency combs (QFCs) are versatile resources for multi-mode entanglement, such as cluster states, crucial for quantum communication and computation. On-chip whispering gallery mode resonators (WGMRs) can generate these states at ultra-low threshold power. This work demonstrates the simultaneous generation of multiple QFCs using a single on-chip silicon nitride WGMR across distinct modal families. It presents a micro-ring resonator with a radius of 240 $\mathrm{\mu m}$, capable of supporting four modal families within the 130 to 260 $\mathrm{THz}$ frequency range for consistency regulation. The results indicate that, by carefully designing the structure of silicon nitride WGMRs, it is possible to generate quantum entangled frequency combs across distinct modal families simultaneously using monochromatic pump light. It is achieved by modulating the pump mode profiles with a spatial light modulator (SLM) or an on-chip inverse-designed mode converter. This approach offers a simple and low-cost method to achieve higher-density entanglement integration on-chip.
- [136] arXiv:2407.06276 (replaced) [pdf, html, other]
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Title: Four no-go theorems on the existence of spin and orbital angular momentum of massless bosonsComments: 25 pagesSubjects: Mathematical Physics (math-ph); High Energy Physics - Theory (hep-th); Optics (physics.optics)
Interest in the so-called orbital angular momentum (OAM) of light is ever-increasing, driven largely by its diverse range of applications, from new imaging techniques to optical tweezers. However, there are fundamental theoretical issues with decomposing the photon angular momentum operator into spin (SAM) and orbital angular momentum parts. While such an SAM-OAM splitting is unambiguous for massive particles, there are numerous proposed splittings for massless photons and no consensus about which is correct. Moreover, it has been shown that most of the proposed SAM and OAM operators do not satisfy the defining commutation relations of angular momentum operators and are thus not legitimate splittings. Here, we prove that it is generally impossible to split the total angular momentum operator of massless bosons, such as photons and gravitons, into spin and orbital parts. The obstruction to such a splitting can be understood as both geometric and topological. We prove two additional no-go theorems which generalize this result, in particular showing that there are no SAM-OAM splittings even if (1) the SAM operator is allowed to represent non-internal symmetries or (2) if one allows the SAM and OAM operators to generate non-SO(3) symmetries. We show how gauge redundant descriptions of massless particles can suggest SAM-OAM splittings which are invalid once gauge-invariance is imposed.
- [137] arXiv:2408.04703 (replaced) [pdf, html, other]
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Title: Extreme heating of minor ions in imbalanced solar-wind turbulenceComments: 15 pages, 9 figures, accepted for publication in ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)
Minor ions in the solar corona are heated to extreme temperatures, far in excess of those of the electrons and protons that comprise the bulk of the plasma. These highly non-thermal distributions make minor ions sensitive probes of the underlying collisionless heating processes, which are crucial to coronal heating and the creation of the solar wind. The recent discovery of the "helicity barrier" offers a mechanism where imbalanced Alfvénic turbulence in low-beta plasmas preferentially heats protons over electrons, generating high-frequency, proton-cyclotron-resonant fluctuations. We use the hybrid-kinetic particle-in-cell code, Pegasus++, to drive imbalanced Alfvénic turbulence in a 3D low-beta plasma with additional passive ion species, He$^{2+}$ and O$^{5+}$. A helicity barrier naturally develops, followed by clear phase-space signatures of oblique ion-cyclotron-wave heating and Landau-resonant heating from the imbalanced Alfvénic fluctuations. The former results in characteristically arced ion velocity distribution functions, whose non-bi-Maxwellian features are shown by linear ALPS calculations to be critical to the heating process. Additional features include a steep transition-range electromagnetic spectrum, the presence of ion-cyclotron waves propagating in the direction of imbalance, significantly enhanced proton-to-electron heating ratios, anisotropic ion temperatures that are significantly more perpendicular with respect to magnetic field, and extreme heating of heavier species in a manner consistent with empirically derived mass scalings informed by measurements. None of these features are realized in an otherwise equivalent simulation of balanced turbulence. If seen simultaneously in the fast solar wind, these signatures of the helicity barrier would testify to the necessity of incorporating turbulence imbalance in a complete theory for the evolution of the solar wind.
- [138] arXiv:2409.07479 (replaced) [pdf, html, other]
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Title: Decomposing force fields as flows on graphs reconstructed from stochastic trajectoriesRamón Nartallo-Kaluarachchi, Paul Expert, David Beers, Alexander Strang, Morten L. Kringelbach, Renaud Lambiotte, Alain GorielyComments: Proceedings of the Third Learning on Graphs Conference (LoG 2024), PMLR 269, Virtual Event, November 26-29, 2024. 26 pages, 12 figuresSubjects: Statistical Mechanics (cond-mat.stat-mech); Dynamical Systems (math.DS); Data Analysis, Statistics and Probability (physics.data-an); Quantitative Methods (q-bio.QM)
Disentangling irreversible and reversible forces from random fluctuations is a challenging problem in the analysis of stochastic trajectories measured from real-world dynamical systems. We present an approach to approximate the dynamics of a stationary Langevin process as a discrete-state Markov process evolving over a graph-representation of phase-space, reconstructed from stochastic trajectories. Next, we utilise the analogy of the Helmholtz-Hodge decomposition of an edge-flow on a contractible simplicial complex with the associated decomposition of a stochastic process into its irreversible and reversible parts. This allows us to decompose our reconstructed flow and to differentiate between the irreversible currents and reversible gradient flows underlying the stochastic trajectories. We validate our approach on a range of solvable and nonlinear systems and apply it to derive insight into the dynamics of flickering red-blood cells and healthy and arrhythmic heartbeats. In particular, we capture the difference in irreversible circulating currents between healthy and passive cells and healthy and arrhythmic heartbeats. Our method breaks new ground at the interface of data-driven approaches to stochastic dynamics and graph signal processing, with the potential for further applications in the analysis of biological experiments and physiological recordings. Finally, it prompts future analysis of the convergence of the Helmholtz-Hodge decomposition in discrete and continuous spaces.
- [139] arXiv:2409.10301 (replaced) [pdf, html, other]
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Title: Decomposition Pipeline for Large-Scale Portfolio Optimization with Applications to Near-Term Quantum ComputingAtithi Acharya, Romina Yalovetzky, Pierre Minssen, Shouvanik Chakrabarti, Ruslan Shaydulin, Rudy Raymond, Yue Sun, Dylan Herman, Ruben S. Andrist, Grant Salton, Martin J. A. Schuetz, Helmut G. Katzgraber, Marco PistoiaSubjects: Optimization and Control (math.OC); Data Analysis, Statistics and Probability (physics.data-an); Portfolio Management (q-fin.PM); Risk Management (q-fin.RM); Quantum Physics (quant-ph)
Industrially relevant constrained optimization problems, such as portfolio optimization and portfolio rebalancing, are often intractable or difficult to solve exactly. In this work, we propose and benchmark a decomposition pipeline targeting portfolio optimization and rebalancing problems with constraints. The pipeline decomposes the optimization problem into constrained subproblems, which are then solved separately and aggregated to give a final result. Our pipeline includes three main components: preprocessing of correlation matrices based on random matrix theory, modified spectral clustering based on Newman's algorithm, and risk rebalancing. Our empirical results show that our pipeline consistently decomposes real-world portfolio optimization problems into subproblems with a size reduction of approximately 80%. Since subproblems are then solved independently, our pipeline drastically reduces the total computation time for state-of-the-art solvers. Moreover, by decomposing large problems into several smaller subproblems, the pipeline enables the use of near-term quantum devices as solvers, providing a path toward practical utility of quantum computers in portfolio optimization.
- [140] arXiv:2409.14386 (replaced) [pdf, html, other]
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Title: Scattering of TE and TM waves and quantum dynamics generated by non-Hermitian HamiltoniansComments: Expanded version, 22 pages, 6 figures; accepted for publication in in Prog. Theor. Exp. PhysSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
The study of the scattering of electromagnetic waves by a linear isotropic medium with planar symmetry can be reduced to that of their TE and TM modes. For situations where the medium consists of parallel homogeneous slabs, one may use the standard transfer matrix technique to address the scattering problem for these modes. We extend the utility of this technique to inhomogeneous permittivity and permeability profiles by proposing a dynamical formulation of the scattering of TE and TM waves in which the transfer matrix for the medium is given in terms of the evolution operator for an effective non-unitary quantum system. This leads to a system of dynamical equations for the reflection and transmission amplitudes. Decoupling these equations we reduce the solution of the scattering problem for TE and TM modes to that of an initial-value problem for a Riccati equation. We discuss the application of this observation in identifying media that do not reflect TE or TM waves with given wavenumber and incidence angle.
- [141] arXiv:2410.00353 (replaced) [pdf, html, other]
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Title: Bringing multilevel quantum master equations into Lindblad form for complete positivity tests: Two approachesSubjects: Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph); Chemical Physics (physics.chem-ph)
While quantum master equations (QMEs) are the primary workhorse in quantum information science, quantum optics, spectroscopy, and quantum thermodynamics, bringing an arbitrary $N$-level QME into Lindbladian form and verifying complete positivity of the associated quantum dynamical map remain open challenges for $N\ge 3$. We explore and implement two independent methods to accomplish these tasks, which enable one to directly compute the Kossakowski matrix of an arbitrary Markovian QME from its Liouvillian. In the first method, due to Hall, Cresser, Li, and Andersson, the Kossakowski matrix elements are obtained by evaluating the action of the Liouvillian on the orthonormal SU($N$) basis matrices and then computing a sum of matrix-product traces. The second method, developed in this work, is based on the real $N$-level coherence vector and relies on the Moore-Penrose pseudo-inverse of a rectangular matrix composed of the structure constants of SU$(N)$. We show that both methods give identical results, and apply them to establish the complete positivity of the partial secular Bloch-Redfield QME for the $\Lambda$ and V-systems driven by incoherent light. We find that the eigenvalues of the Kossakowski matrix of these seemingly different three-level systems are identical, implying close similarities of their dissipative dynamics. By facilitating the expression of multilevel Markovian QMEs in Lindblad form, our results enable testing the QMEs for complete positivity without solving them, as well as restoring complete positivity by keeping only non-negative eigenvalues of the Kossakowski matrix.
- [142] arXiv:2410.20886 (replaced) [pdf, html, other]
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Title: CODES: Benchmarking Coupled ODE SurrogatesComments: 13 pages, 10 figures, accepted for the Machine Learning and the Physical Sciences workshop at NeurIPS 2024, source code available on GitHub at this https URLSubjects: Machine Learning (cs.LG); Instrumentation and Methods for Astrophysics (astro-ph.IM); Computational Physics (physics.comp-ph)
We introduce CODES, a benchmark for comprehensive evaluation of surrogate architectures for coupled ODE systems. Besides standard metrics like mean squared error (MSE) and inference time, CODES provides insights into surrogate behaviour across multiple dimensions like interpolation, extrapolation, sparse data, uncertainty quantification and gradient correlation. The benchmark emphasizes usability through features such as integrated parallel training, a web-based configuration generator, and pre-implemented baseline models and datasets. Extensive documentation ensures sustainability and provides the foundation for collaborative improvement. By offering a fair and multi-faceted comparison, CODES helps researchers select the most suitable surrogate for their specific dataset and application while deepening our understanding of surrogate learning behaviour.
- [143] arXiv:2410.24115 (replaced) [pdf, html, other]
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Title: gSeaGen code by KM3NeT: an efficient tool to propagate muons simulated with CORSIKAS. Aiello, A. Albert, A.R. Alhebsi, M. Alshamsi, S. Alves Garre, A. Ambrosone, F. Ameli, M. Andre, L. Aphecetche, M. Ardid, S. Ardid, H. Atmani, J. Aublin, F. Badaracco, L. Bailly-Salins, Z. Bardačová, B. Baret, A. Bariego-Quintana, Y. Becherini, M. Bendahman, F. Benfenati, M. Benhassi, M. Bennani, D.M. Benoit, E. Berbee, V. Bertin, S. Biagi, M. Boettcher, D. Bonanno, A.B. Bouasla, J. Boumaaza, M. Bouta, M. Bouwhuis, C. Bozza, R.M. Bozza, H. Brânzaş, F. Bretaudeau, M. Breuhaus, R. Bruijn, J. Brunner, R. Bruno, E. Buis, R. Buompane, J. Busto, B. Caiffi, D. Calvo, A. Capone, F. Carenini, V. Carretero, T. Cartraud, P. Castaldi, V. Cecchini, S. Celli, L. Cerisy, M. Chabab, A. Chen, S. Cherubini, T. Chiarusi, M. Circella, R. Cocimano, J.A.B. Coelho, A. Coleiro, A. Condorelli, R. Coniglione, P. Coyle, A. Creusot, G. Cuttone, R. Dallier, A. De Benedittis, B. De Martino, G. De Wasseige, V. Decoene, I. Del Rosso, L.S. Di Mauro, I. Di Palma, A.F. Díaz, D. Diego-Tortosa, C. Distefano, A. Domi, C. Donzaud, D. Dornic, E. Drakopoulou, D. Drouhin, J.-G. Ducoin, R. Dvornický, T. Eberl, E. Eckerová, A. Eddymaoui, T. van Eeden, M. Eff, D. van Eijk, I. El Bojaddaini, S. El Hedri, V. Ellajosyula, A. Enzenhöfer, G. Ferrara, M. D. Filipović, F. Filippini, D. Franciotti, L.A. FuscoComments: 27 pages, 13 figures, submitted to Computer Physics CommunicationsSubjects: High Energy Physics - Experiment (hep-ex); Instrumentation and Methods for Astrophysics (astro-ph.IM); Computational Physics (physics.comp-ph)
The KM3NeT Collaboration has tackled a common challenge faced by the astroparticle physics community, namely adapting the experiment-specific simulation software to work with the CORSIKA air shower simulation output. The proposed solution is an extension of the open-source code gSeaGen, allowing for the transport of muons generated by CORSIKA to a detector of any size at an arbitrary depth. The gSeaGen code was not only extended in terms of functionalities but also underwent a thorough redesign of the muon propagation routine, resulting in a more accurate and efficient simulation. This paper presents the capabilities of the new gSeaGen code as well as prospects for further developments.
- [144] arXiv:2411.10191 (replaced) [pdf, other]
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Title: FengWu-W2S: A deep learning model for seamless weather-to-subseasonal forecast of global atmosphereComments: 23 pages,8 figuresSubjects: Machine Learning (cs.LG); Artificial Intelligence (cs.AI); Atmospheric and Oceanic Physics (physics.ao-ph)
Seamless forecasting that produces warning information at continuum timescales based on only one system is a long-standing pursuit for weather-climate service. While the rapid advancement of deep learning has induced revolutionary changes in classical forecasting field, current efforts are still focused on building separate AI models for weather and climate forecasts. To explore the seamless forecasting ability based on one AI model, we propose FengWu-Weather to Subseasonal (FengWu-W2S), which builds on the FengWu global weather forecast model and incorporates an ocean-atmosphere-land coupling structure along with a diverse perturbation strategy. FengWu-W2S can generate 6-hourly atmosphere forecasts extending up to 42 days through an autoregressive and seamless manner. Our hindcast results demonstrate that FengWu-W2S reliably predicts atmospheric conditions out to 3-6 weeks ahead, enhancing predictive capabilities for global surface air temperature, precipitation, geopotential height and intraseasonal signals such as the Madden-Julian Oscillation (MJO) and North Atlantic Oscillation (NAO). Moreover, our ablation experiments on forecast error growth from daily to seasonal timescales reveal potential pathways for developing AI-based integrated system for seamless weather-climate forecasting in the future.