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Physics

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Wednesday 16 September

Fluid Dynamics

Control of axial dispersion in polymeric flows: magnetic effect versus electroosmotic effect

Xiaoping Wang, Mengqi Zhang and Haitao Qi

Since Taylor's seminal work on the dispersion of soluble matter, the modeling and control of solute dispersion have received considerable attention. This study investigates the solute dispersion in polymer solutions driven by unsteady magnetohydrodynamic-oscillatory electroosmotic flow within a microtube, aiming to reveal the transport mechanisms in complex rheological media through microscale flow. Firstly, based on the Debye-Hückel approximation, analytical solutions for the electric potential and velocity distributions of mixed magnetohydrodynamic-electrohydrodynamic flows are rigorously derived. Subsequently, using Sankarasubramanian & Gill's generalized dispersion model, mathematical models are developed to systematically investigate the temporal evolution of hydrodynamic dispersion. By investigating the synergistic modulation of electrokinetic and magnetic fields, we identify three distinct flow regimes, namely the electric-field-dominant, competitive transition, and magnetic-field-limited regimes, and quantitatively define their boundaries and evolution with oscillatory Reynolds number $Re$ and Deborah number $De$, thus allowing accurate flow regime classification. Moreover, a non-monotonic critical response governing solute dispersion is observed over a wide range of oscillatory Reynolds numbers, which provides a novel control paradigm for microfluidic mixing and separation. Additionally, through a comparative analysis of fractional Maxwell, classical Maxwell, and Newtonian fluids, we show that microscopic structural relaxation plays a crucial role in macroscopic solute transport under multi-field coupling. Our findings help to reveal flow mechanisms for precise mass transport control in electro-magnetically coupled systems, advancing the development of microfluidic devices and biomedical detection technologies.
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Optics

On imaging capabilities of the Imaging and Medical beamline at the Australian Synchrotron

T.E. Gureyev, K.M. Pavlov, C.J. Hall et al. (+6 more)

Several propagation-based and analyser-based X-ray phase-contrast imaging experiments with over 100 m between the imaged objects and the detector were carried out at the Imaging and Medical beamline (IMBL) of the Australian Synchrotron. These experiments were aimed at characterization of possible phase-contrast imaging setups at IMBL. Effects of the beam divergence, polychromaticity and X-ray source size on the contrast and spatial resolution of images were evaluated quantitatively in different imaging scenarios. The results of this work will be used for improving the existing and developing new imaging capabilities at the beamline. Applications to X-ray phase-contrast tomography of biomedical samples, particularly for medical breast cancer imaging, are briefly discussed.
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All authors T.E. Gureyev, K.M. Pavlov, C.J. Hall, A. Maksimenko, D. Pelliccia, D.M. Paganin, A.W. Stevenson, A. Entezam, H.M. Quiney

Geophysics

Gravitational energy released when Earth quakes: Heat supply for island-arc volcanism

Benjamin F. Chao, Sheng-An Shih, Frederic Deschamps et al. (+1 more)

We address a long-standing paradox in plate tectonics concerning the thermodynamics of its very origin: What supplies the thermal energy for the intense island-arc volcanism at the subduction zones, the supposedly cool end of the mantle convection? We surmise a first-principle physics model tracking the gravitational energy (Eg)-heat conversion within the mantle convection. The scenario points to a great amount of Eg release of ~10 TW induced by the thrust-faulting earthquakes that occur predominantly in the upper mantle at the subduction zones. Generally ~1000 times greater than the seismic energy release or nearly a quarter of the total terrestrial heat flow, this Eg release, upon conversion into heat in the irreversible convection process, supplies amply for the island-arc volcanism. Meanwhile similar but opposite and less vigorous Eg gains at ~2 TW occur at the diverging plate boundaries via the normal-faulting earthquakes. This model resolves the said paradox, and more importantly provides a new paradigm pointing to an active role of seismicity in the plate tectonic energetics and evolution of the convecting mantle.
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All authors Benjamin F. Chao, Sheng-An Shih, Frederic Deschamps, Eh Tan

Mesoscale and Nanoscale Physics

Unconventional linear transverse exciton transport in valley-layer coupling two-dimensional materials

Ci Li

Valley-layer coupling (VLC) two-dimensional (2D) materials define a distinct class of quantum systems in which valleys are related by crystal, rather than time-reversal ($\mathcal{T}$) symmetry, enabling gate-controlled valley-contrasted layer polarization. Here we extend this concept to excitons. Using TiSiCo as a prototype VLC material, we show that a perpendicular electric field $E_{\perp}$ controls exciton- dispersion anisotropy and thereby generates unconventional linear transverse exciton transport in both monolayer and twisted bilayer structures. In the monolayer, this response is characterized by anisotropy-induced transverse conductivities, arising from the antisymmetric combination of diagonal elements in the conductivity tensor and strongly tunable by $E_{\perp}$. In the twisted bilayer, symmetry additionally permits transverse responses from the symmetric part of the conductivity tensor. Since intralayer excitons in different layers are connected by the Förster coupling, these symmetric and antisymmetric responses coexist and compete with the recently proposed $\mathcal{T}$-even layer Hall and Nernst exciton counterflow. This interplay is highly tunable by twisted angle, temperature, and the direction of the in-plane driving force, providing a route to disentangle distinct transverse exciton transport signals experimentally. Our results establish $E_{\perp}$ as a powerful knob for controlling exciton transport via VLC and identify VLC 2D materials as a promising platform for engineered excitonic phenomena.
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High Energy Physics (Theory)

Central charge and black hole entropy for regular extremal black-bounce spacetimes

Xu Ye, Shan-Ping Wu, Yu-Kun Zhang et al. (+1 more)

The Bekenstein-Hawking entropy, proportional to one quarter of the horizon area, is fundamental in black hole thermodynamics and can also be understood via the AdS/CFT correspondence, such as the 3D BTZ black hole and 2D CFT. In this work, we adopt the Kerr/CFT approach to analyze the central charge and black hole entropy for regular extremal black-bounce spacetimes, including the counterparts of the Kerr, Kerr-Newman, and Reissner-Nordström black holes. These spacetimes are free of curvature singularities at $r=0$. We derive the near horizon geometries of these spacetimes and find that they exhibit enhanced symmetry, namely SL$(2,\mathbb{R})\times \mathrm{U}(1)$ or SL$(2,\mathbb{R}) \times \mathrm{SO}(3)$. By imposing appropriate boundary conditions, we analyze their asymptotic symmetry groups, which contain diffeomorphisms as well as the $\mathrm{U}(1)_{\rm gauge}$ symmetry arising from the electromagnetic field. We then extract the central charge from the charge algebra and evaluate the left-moving temperature of the Frolov-Thorne vacuum. It is worth emphasizing that in the black-bounce Kerr-Newman case, the central charge from the electromagnetic contribution vanishes. Furthermore, in the black-bounce Reissner-Nordström case, we uplift the 4D geometry to a 5D configuration by incorporating a $\mathrm{U}(1)$ gauge fiber. Our results show that the microscopic entropy calculated from the Cardy formula is consistent with the Bekenstein-Hawking entropy. This agreement suggests that the Kerr/CFT approach remains valid for certain regular spacetimes without curvature singularities, thereby providing a microscopic statistical understanding of black hole entropy.
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All authors Xu Ye, Shan-Ping Wu, Yu-Kun Zhang, Shao-Wen Wei

Computational Physics

MLegS: A modern mapped Legendre spectral method solver for unbounded domains with parallelization

Sangjoon Lee and Jinge Wang

MLegS is an open-source Modern Fortran code package for solving linear and nonlinear time-dependent partial differential equations on radially unbounded domains. It builds on an earlier in-house prototype, recasting it as a modular solver with a unified interface for fields, transforms, and spectral operators. Within this framework, the numerical formulation maps $0\leq r<\infty$ onto a finite interval, where associated Legendre functions provide the radial basis, while Fourier series represent the periodic azimuthal and axial directions. The mapped radial basis represents radial infinity without imposing an artificial boundary condition at finite radius while incorporating the regularity required at $r=0$ according to azimuthal order. The implementation distributes the corresponding field layouts using the Message-Passing Interface (MPI), with strong- and weak-scaling measurements extending to 512 cores across four compute nodes. Beyond parallel performance, three examples assess the solver across diffusion, reaction-diffusion, and vortex dynamics: closed-form diffusion solutions establish spectral spatial convergence and the design orders of both semi-implicit integrators; a Fisher-Kolmogorov-Petrovsky-Piskunov front matches the linearized solution and propagates at the classical speed within its logarithmic correction; and vortex-pair simulations based on toroidal-poloidal decomposition yield a measured Crow growth rate $2.7\%$ above the theoretical prediction and demonstrate the reconnection of the vortex pair.
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Solar and Stellar Astrophysics

Physics-Informed Neural Networks for Fast Multilayer Spectral Inversion of H{\alpha} 6562.8 A and Ca II 8542.1 A Spectra

Ziyang Zhang, Qin Li, Vasyl B. Yurchyshyn et al. (+4 more)

Strong chromospheric absorption lines such as H$\alpha$ 6562.8 A and Ca II 8542.1 A provide vital diagnostics of plasma dynamics and thermal structure in the solar chromosphere. Multilayer spectral inversion (MLSI) offers a physically interpretable framework for modeling these lines using a finite number of radiative-transfer layers, but conventional MLSI relies on pixel-by-pixel nonlinear least-squares fitting, making it computationally expensive for large imaging spectroscopic data sets. Here, we introduce a physics-informed neural-network (PINN) framework to accelerate MLSI while preserving its analytic radiative-transfer formulation. The network predicts MLSI parameters directly from observed line profiles and passes them through a differentiable MLSI forward model to synthesize spectra. Training follows a two-stage approach: an initial stage optimized solely via spectral reconstruction loss, followed by fine-tuning that combines spectral consistency with parameter-space supervision from conventional MLSI results on a single reference image. This strategy eliminates the need for large precomputed training sets while maintaining physical interpretability. Applied to Fast Imaging Solar Spectrograph (FISS) observations from the Goode Solar Telescope (GST) targeting both quiet-Sun and active-region regions, MLSI-PINN parameter maps reproduce the primary spatial structures of direct inversions, achieving an arithmetic mean pixel-wise Pearson correlation coefficient of 0.933 across all evaluated parameters. The reconstructed spectra closely match both observed profiles and conventional MLSI fits. Post-training, MLSI-PINN processes a raster in approximately 5-15 seconds compared to 3-5 minutes for conventional MLSI, delivering an inference speedup of about 12-60 times without substantial loss in reconstruction quality, enabling efficient MLSI analysis on large chromospheric data sets.
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All authors Ziyang Zhang, Qin Li, Vasyl B. Yurchyshyn, Kangwoo Yi, Haimin Wang, Wenda Cao, Bo Shen

Quantum Physics · Cross-listed from math.CO

Perfect state transfer under matrix powers: parity and spectral arithmetic

Xingkun Song

For a real symmetric matrix $H$ and distinct vertices $a,b$, we classify exponents $k$ for which $H^k$ has perfect state transfer (PST) from $a$ to $b$. If their supported eigenvalues are integer multiples of a common positive number, every odd exponent reduces to $H$ and every positive even exponent reduces to $H^2$. We determine the minimum transfer times using a greatest common divisor of supported spectral differences. For rational symmetric matrices, symmetry of the source vertex support about zero implies the odd-power equivalence without a commensurability assumption; this includes all bipartite graphs. If the source vertex supports zero, PST under one positive even power implies PST under every positive even power. For a symmetric three-point quadratic spectrum whose outer projection signs agree and differ from the central sign, a nonzero rational shift leaves exactly one PST exponent. We classify all adjacency powers of hypercubes, cycles, and Johnson graphs, and all adjacency squares of paths. In particular, the adjacency matrix of $P_7$ has PST from vertex $2$ to vertex $6$ only at exponent $2$.
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Chaotic Dynamics

A New Route to Chaos through the Geometric Composition of Non-Normal Amplification

D. Sornette, V. R. Saiprasad and V. Troude

Chaos emerges when stretching is repeatedly recycled by reinjection. We uncover a new route to chaos in which the decisive variable is the temporal order of non-normal tangent maps: periodic and chaotic states can share essentially the same one-step stretching statistics while their ordered products acquire opposite Lyapunov growth. We introduce the ordered-product growth rate $h_L$ over $L$ successive tangent maps, which reveals how states indistinguishable at one step separate under geometric composition and identifies the finite composition scale at which chaos emerges. We use this mechanism to establish a new form of global chaos control: minute phase actions reorient the successive non-normal amplification directions so that their geometric composition becomes contracting, suppressing chaos at fixed dissipation without reducing local amplification or targeting a preselected orbit.
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Fluid Dynamics

Library-learning-assisted robust principal component analysis for denoising severely corrupted flow fields

Pablo Koop, Isabel Scherl and Kai Fukami

Large-amplitude entrywise corruption can distort flow-field data and contaminate extracted modes. Robust principal component analysis (RPCA) separates low-rank flow content from a sparse corruption component, but recovery deteriorates when corruption occupies a large fraction of measurements. We introduce library-learning-assisted robust principal component analysis (LLA-RPCA), which restricts the recovered spatial basis to combinations of functions from a fixed candidate library and prescribes the available modal capacity. Here, the library contains standard trigonometric functions and graph-Laplacian eigenfunctions. The decomposition is solved via augmented-Lagrangian alternating minimization. The method is evaluated on a post-stall NACA0012 wake, oscillating-cylinder wake video data, and particle image velocimetry (PIV) measurements of a flat plate undergoing a transverse gust encounter. For the first two cases, synthetic large-amplitude entrywise corruption is imposed over fractions from 0% to 90%. LLA-RPCA retains coherent wake structures and recovers dominant linear modes at corruption levels where standard RPCA retains residual corruption, attenuates the reconstructed field, or collapses to a one-dimensional reconstruction. For the experimental gust-encounter case, standard RPCA exhibits a trade-off between attenuating coherent flow content and retaining naturally occurring PIV artifacts as its tuning factor increases. Conversely, LLA-RPCA suppresses artifacts while consistently preserving coherent velocity and derived-vorticity structures. These results indicate that a library-constrained reconstruction with prescribed modal capacity improves denoising and modal recovery when the prescribed representation adequately captures the relevant spatial content.
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Quantum Physics

Sublattice-selective control of spin reversal in metasurface-coupled Kagome interfaces

Ximo Wang, Qiwei Han, Zhenqi Bai et al. (+3 more)

Coherent manipulation of photonic interface states requires a control field that matches their internal mode structure. We study this requirement in a two-component Kagome lattice motivated by photon-mediated exchange near a nonlinear nonlocal metasurface. The Dirac spinors show why uniform Raman control cannot couple opposite-spin, same-valley interface modes at leading order, even when their spatial envelopes coincide. A $1:1:-2$ sublattice pattern removes this cancellation and maximizes the projected coupling at fixed root-mean-square amplitude within the diagonal-control class. We test this control scheme through full-zone topology and complete lattice propagation. For a smooth, gapped interface, a $720$-dimensional calculation gives target-mode fidelity $0.999937$ with leakage $6.27\times10^{-5}$ at RMS drive $0.04t$. Trace-preserving dynamics gives the separate survival condition needed for successful conversion. An exploratory three-dimensional lithium-niobate supercell reproduces the complex addressing pattern with $0.373\%$ relative error and provides nonlocal exchange, decay and electro-optic frequency-conversion matrices. The mode-resolved control principle thus gives quantitative electromagnetic design targets; the full spin-dependent device realization still requires further calibration.
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All authors Ximo Wang, Qiwei Han, Zhenqi Bai, Ruyue Guo, Min Feng, Yichi Zhang

Materials Science

High-performance orbital-torque magnetic memory on the 300-mm platform

Dinggui Zeng, Yang Gao, Jinyu Duan et al. (+24 more)

Contemporary memory technologies are increasingly constrained by the fundamental trilemma of storage capacity, access latency, and power consumption. Among the emerging technologies, spin-orbit torque magnetic random-access memory (SOT-MRAM) shows promise to circumvent these challenges, owing to its fast switching dynamics and high endurance. However, the application of SOT-MRAM is hindered by the relatively low write and read efficiencies, resulting in a large bitcell area and an insufficient sensing margin. Meanwhile, the involvement of an ultrathin spin-source channel, typically within a few nanometers, imposes technological challenges for mass production. Here, we resolve these issues on a 300-mm wafer platform by exploiting the emerging orbital degree of freedom and the resultant orbital torque (OT) from the relatively thick Ti/W bilayer. In particular, OT memory nanodevices exhibit a giant tunnel magnetoresistance (TMR) of 182%, nanosecond-scale response, 1012 endurance, together with an enhanced switching efficiency (E_b/I_c), which consequently enables an ultra-low write energy of less than 0.1 pJ/bit. Our findings demonstrate that orbital angular momentum can be implemented for building energy-efficient MRAM devices, offering a practical pathway towards low-latency memory that is demanded for high-performance computing and AI applications.
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All authors Dinggui Zeng, Yang Gao, Jinyu Duan, Lei Zhao, Yuhao An, Xing He, Jintao Ke, Yonglong Ga, Shasha Wang, Zhenghui Ji, Muyuan Chen, Hengan Zhou, Xuejie Xie, Enlong Liu, Junlu Gong, Qijun Guo, Yihui Sun, Zejie Zheng, Weiming He, Xiaolei Yang, Fantao Meng, Yaohua Wang, Hongxin Yang, Delin Zhang, Yong Jiang, Wanjun Jiang, Shikun He

Astrophysics of Galaxies

A Possible Hidden Hot Halo Component Revealed by Joint X-ray and Sunyaev–Zel'dovich Observations

Jiang-Tao Li, Rui Huang, Joel N. Bregman et al. (+2 more)

Massive galaxies are expected to host extended halos of hot gas that contain a substantial fraction of their baryons and feedback energy. X-ray observations probe the dense, X-ray-bright component of this circumgalactic medium (CGM), while the thermal Sunyaev-Zel'dovich (SZ) effect is also sensitive to lower-density gas through its integrated thermal pressure. We present the first spatially resolved joint X-ray and SZ analysis of a massive isolated disk galaxy, using deep XMM-Newton observations of NGC 4594 from the X-raying the Accretion Reservoir Transferred to the ATmosphere Orbiting a Massive Spiral (XART-ATOMS) program, together with multiple independent Planck-based SZ reconstructions. The measured SZ signal in the inner halo appears to exceed the value predicted from the X-ray-derived gas properties, even after accounting for major systematic uncertainties. Our preferred interpretation is that an additional lower-density CGM component contributes little to the observed soft X-ray emission but carries substantial thermal pressure. Under a simple two-phase model in approximate pressure equilibrium, the most probable X-ray-to-SZ ratio implies that the detected X-ray-emitting gas occupies only a small fraction of the halo volume, with a characteristic filling factor of f_X ~ (4-6)x10^-3 near r~50 kpc. Such a small filling factor implies that single-phase X-ray analyses can underestimate the baryon mass contained in the hot CGM by a factor of ~2.5, while the thermal energy content of the CGM is underestimated by about one order of magnitude. The non-detection of the additional component in the X-ray spectra requires it to be very hot and/or spatially extended, so weak in the soft X-ray emissions. These results favor the presence of a "hidden" X-ray-faint hotter halo component, while alternative interpretations, including a nonthermal contribution, are not excluded.
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All authors Jiang-Tao Li, Rui Huang, Joel N. Bregman, Q. Daniel Wang, Cameron Pratt

Quantum Physics

Algorithmic Design of Heralded Linear Optical Circuits for Multipartite Entanglement

Jaehee Kim, Hon Wai Lau, William J. Munro et al. (+2 more)

Heralded multipartite entanglement is a key resource for various quantum information tasks. However, designing linear optical circuits that generate specific target states is generally challenging due to the complexity of the required optical structures. Here we formulate the design of heralded photonic circuits as an algorithmic graph-search problem. Our framework enables the automated construction and optimization of heralded photonic circuits by substantially reducing the search space using the linear quantum graph (LQG) picture. Our strategy reconstructs circuit structures as graphs in the picture and identifies suitable graphs automatically. As a result, we design efficient schemes for a broad range of useful multipartite resource states, including hypergraph magic states, quantum error correcting codes, general three-qubit states and length-1 caterpillar graph states. Our work establishes an algorithmic framework for the systematic discovery of heralded resource states, laying the foundation for the automated design of increasingly complex multipartite entangled resources.
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All authors Jaehee Kim, Hon Wai Lau, William J. Munro, Joonsuk Huh, Seungbeom Chin

Astrophysics of Galaxies

Does galaxy-scale compactness regulate nebular electron density? A cross-scale test with DESI

Shihong Liu and Yu Rong

Nebular electron density, $n_e$, traces ionized gas in small-scale H\,ii regions and diffuse ionized structures, whereas galaxy stellar surface density, $\Sigma_\star$, measures compactness on kpc scales. Whether these quantities are correlated is therefore a cross-scale question rather than a geometrical identity. We test whether nebular electron density varies systematically with galaxy-scale stellar compactness after controlling for the correlated effects of stellar mass and star-formation rate (SFR). We use DESI DR 1 spectra to test this cross-scale connection in AGN-clean star-forming galaxies at $0.10<z<0.44$. We divide each redshift interval into tertiles of $\Sigma_\star=M_\star/(2\pi R_e^2)$. We construct one controlled sample in which the $M_\star$ distributions are matched across the three compactness tertiles, and a second in which their joint $M_\star$–SFR distributions are matched, thereby minimizing the influence of these correlated galaxy properties. For each compactness tertile, we stack the galaxy spectra with equal weight and use the stacked spectrum to measure the average $n_e$ of the galaxies in that sample. The average $n_e$ increases systematically toward higher stellar surface density in all redshift intervals. This is the first controlled population-level evidence for a correlation between kpc-scale galaxy stellar surface density (compactness) and the average $n_e$ of ionized gas on subgalactic scales. Its persistence after matching both $M_\star$ and SFR suggests that a more compact stellar configuration may promote higher gas pressure and/or stronger confinement of ionized gas, linking galaxy-scale structure to nebular conditions.
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Solar and Stellar Astrophysics

Three-dimensional simulations of accretion disks in pre-CE systems – II. Accretion efficiency and angular momentum transport

Ana L. Juarez-Garcia, Mike Y. M. Lau, Orsola De Marco et al. (+3 more)

Rapid mass transfer preceding a common envelope event is a critical yet poorly understood stage of binary stellar evolution, setting the initial conditions for the common envelope inspiral and for the formation of compact binary stars. We present three-dimensional smoothed particle hydrodynamics simulations of accretion disk formation during this phase using the Phantom code. We model the final $21~yr$ of Roche lobe overflow from a $7~M_{\odot}$ red giant onto a $1.4~M_{\odot}$ neutron star companion, with the mass transfer rate prescribed by a 1D MESA model. Over this interval, the mass transfer rate increases from $1.3\times10^{-4}$ to $1.0\times10^{-1}~M_\odot~yr^{-1}$. An accretion disk forms around the neutron star, reading a mass of $5.0\times10^{-3} ~ M_{\odot}$, a radius of $40~R_{\odot}$ and an aspect ratio H/R$\sim 0.1$ by the end of the simulation. A direct comparison with the grid-based simulation of Juarez-Garcia et al. (2025) shows that the two codes produce disk masses that agree to within 6%. The accretion rate onto the neutron star reaches $5.2\times10^{-3}~M_\odot~yr^{-1}$, corresponding to 14% of the mass injection rate and greatly exceeding the Eddington limit. We demonstrate that this accretion rate is consistent with being driven by turbulent angular momentum transport, with an effective viscosity parameter $\alpha_{\rm eff}~=~0.03-0.06$. Ejecta leaving the binary system carries specific angular momentum approximately 90% that of the $L_{2}$ Lagrange point, equivalent to $\sim10$ times the binary's specific orbital angular momentum. This indicates that $L_{2}$ mass loss efficiently reduces the binary orbital separation.
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All authors Ana L. Juarez-Garcia, Mike Y. M. Lau, Orsola De Marco, Lionel Siess, Daniel J. Price, Rebecca Nealon

Quantum Physics

Fourier Analysis of Parametrized Interactive Quantum Classifiers

Fábio Novaes, Fernando M. de Paula Neto and João V. M. Cardoso

Interactive Quantum Classifiers (IQCs) constitute a family of quantum machine learning models inspired by open quantum systems, in which the interaction between a target qubit and an environment is described by a Hamiltonian. Previous works introduced alternative Hamiltonian parameterizations and showed empirically that they can improve classification performance, but the role of these parameters in the resulting classifier remains poorly understood. In this work, we derive a closed-form expression for the reduced quantum channel generated by a parametrized IQC with a single target qubit. The analytical solution explicitly reveals how the Hamiltonian parameters control the constant, sine, and cosine components of the classifier output, establishing a Fourier interpretation of the induced feature map. This analysis motivates a generalized family of Hamiltonian encodings, including matrix-parameterized environmental Hamiltonians whose Fourier components depend on linear combinations of input features, thereby enabling non-separable Fourier structures. Numerical experiments on synthetic and real-world datasets show that the proposed models can improve classification performance on several nonlinear benchmarks. The generalized matrix encoding achieves the strongest aggregate performance in the evaluated benchmark, while a simpler four-parameter extension often attains comparable performance with substantially fewer trainable parameters. We additionally characterize the generated state ensembles using the standard fidelity-based expressibility measure, finding that global expressibility does not directly predict classification performance. Our results provide an analytical characterization of parametrized Hamiltonians in Interactive Quantum Classifiers and establish Fourier analysis as a useful framework for understanding and designing open-system-inspired quantum learning models.
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Mesoscale and Nanoscale Physics

Experimental assessment of the Wiedemann-Franz law in thin metal films using thermoreflectance and electrical measurements

Zhiwei Deng, Jinlong Ma and Puqing Jiang

Accurate thermal properties of metal thin films are essential for microelectronic thermal modeling and for interpreting thermoreflectance measurements when signals are sensitive to film thermal transport. In practice, film thermal conductivity is commonly inferred from electrical resistivity via the Wiedemann-Franz (WF) law with the Sommerfeld-Lorenz number L_0, neglecting phonon contributions and microstructure-dependent scattering. Here, we combine square-pulsed source (SPS) thermoreflectance with van der Pauw measurements to characterize thermal and electrical transport in Al, Ti, and Ta thin films prepared by thermal evaporation, e-beam evaporation, and magnetron sputtering. SPS measurements from 80 to 300 K yield the film thermal conductivity k_m and volumetric heat capacity C_m, with C_m agreeing with bulk values within +/-8%. Compared with WF-based estimates using L_0 and a modeled resistivity, h̊o}_model (T)=h̊o}_bulk (T)+h̊o}_0, k_m deviates by 5-20% for Al and Ti and up to 40% for sputtered Ta at 300 K. While the smaller deviations are comparable to experimental uncertainty, the large mismatch for Ta demonstrates the limitation of applying the bulk L_0 to highly resistive metal films. Apparent Lorenz numbers L_app=k_m h̊o}_meas/T from 150 to 300 K further reveal that deposition-induced disorder, grain-boundary scattering, and possible phase-related effects can modify the correlation between heat and charge transport in thin metal films. These results clarify the applicability of the WF law to deposited metal thin films and offer practical guidance for thermal modeling and thermoreflectance analysis.
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Statistical Mechanics

The quantum Mpemba effect in symmetric random Clifford circuits

Shion Yamashika, Filiberto Ares and Pasquale Calabrese

The quantum Mpemba effect is the counterintuitive phenomenon whereby a quantum state initially farther from equilibrium relaxes faster than one initially closer to it. We demonstrate this effect in random Clifford circuits with a conserved $\mathrm{U}(1)$ charge, using the entanglement asymmetry to characterize relaxation through dynamical symmetry restoration. Exact numerical simulations show that an initially more asymmetric state can become locally more symmetric than an initially less asymmetric one. We explain this behavior by mapping the dynamics onto a charge-conserving quantum automaton, in which the decay of the entanglement asymmetry is controlled by the statistics of encounters between two particle species evolving according to a symmetric simple exclusion process. This mapping yields an analytic expression for the entanglement asymmetry and provides a simple microscopic mechanism for the quantum Mpemba effect: stronger initial symmetry breaking corresponds to a denser particle configuration, which enhances the frequency of particle encounters and thereby accelerates symmetry restoration.
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Statistical Mechanics

Macroscopic Response Diagnoses the Noise Sensitivity of Terminal Outcomes

Bo Li and Chaoqian Wang

Can the terminal macroscopic outcome of a many-body system be inferred from its microscopic initial data without simulating the full trajectory? Rather than construct such a shortcut, we address a more fundamental question for Gaussian microscopic inputs: can any fixed Wiener-Hermite degree retain a nonvanishing fraction of the variance of the terminal outcome as the system grows? We consider homogeneous systems with independent Gaussian disorder in which all microscopic coordinates are symmetry-equivalent, the terminal event is monotone in each disorder variable, and a uniform disorder shift is exactly equivalent to a control-field shift with a size-independent conversion factor. Using forward and inverse Gaussian influence bounds together with a Gaussian Russo formula, we derive a directly measurable criterion that is both necessary and sufficient for noise sensitivity. Specifically, the correlation between the original and coordinate-perturbed terminal outcomes vanishes asymptotically for every fixed nonzero level of coordinatewise noise if and only if the slope of the outcome probability with respect to the control field at the balanced threshold grows more slowly than the square root of the system volume. Event-driven simulations of the three-dimensional driven random-field Ising model up to linear size 192 find that both the normalized response and the correlations between perturbed samples decrease overall, consistent with the noise-sensitive regime at finite size. For spatial Stag-Hunt dynamics with prescribed seeds, the criterion generalizes through an effective number of influential coordinates. Separately, simulations of a path-dependent best-response game show, over the sizes studied, that the terminal equilibrium can depend on the update schedule while still carrying substantial finite-order predictive information.
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Quantum Physics

Qurrium: A Python package for randomized measurement-based estimation of quantum state properties

Huai-Chun Chang, Teik-Hui Lee, Arthur Strauss et al. (+2 more)

Estimating quantum state properties is essential across a wide range of applications, from studying quantum many-body physics to benchmarking quantum hardware. We present Qurrium, a Python package built on Qiskit that implements randomized measurement protocols for estimating purity, second-order Rényi entropy, expectation values of Pauli observables, and state overlap. In this paper, we focus on the classical shadow protocol and demonstrate two workflows in Qurrium. One is the end-to-end workflow that integrates quantum circuit preparation, simulation, measurement, and analysis. The other is the standalone estimation workflow that accepts pre-collected measurement data from any hardware platform in Qurrium's data format. We demonstrate both workflows through examples of a cluster state and an Ising time-evolved state. Furthermore, we report results obtained from a superconducting quantum processor developed by Academia Sinica and analyzed using the standalone estimation workflow. Qurrium is built on Qiskit, the dominant framework in quantum computing software, making it directly accessible to the large community of researchers already working with Qiskit. The source code is openly available at https://github.com/qurrium/qurrium and the example code is provided at https://github.com/qurrium/classical-shadow-examples.
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All authors Huai-Chun Chang, Teik-Hui Lee, Arthur Strauss, Yu-Cheng Lin, Hsiu-Chuan Hsu

Optics

Environmental qualification and performance of a CubeSat-scale dual optical frequency comb payload for space applications

Stephanie D. Leifer, Matthew J. Kelley, Natalie Walsh et al. (+23 more)

We report the environmental qualification and performance of CombSat, a dual optical frequency comb payload designed for deployment on a 12U CubeSat in low Earth orbit. The payload integrates two self-referenced, 200 MHz hybrid fiber-waveguide frequency combs, a narrow-linewidth optical reference, a heterodyne beat detection unit, and FPGA-based control electronics in a total mass of 8.3 kg and volume of 5.7 L, and nominal power consumption of 21W. We describe the mechanical, thermal, and radiation-tolerant design features of the system and present the results of random vibration, storage temperature cycling, and thermal-vacuum testing conducted in accordance with NASA's General Environmental Verification Standard. We show that key comb performance metrics including oscillator and amplifier output power, frep, fCEO, and fopt signal-to-noise ratios, and integrated phase noise, remain within specification after environmental exposure, and we discuss observed failure modes and design modifications that improved robustness. These results demonstrate that compact, low power, fully stabilized, autonomous dual-comb systems can be engineered and qualified for spaceflight on CubeSat platforms, providing a path forward for future low-cost comb-based space applications.
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All authors Stephanie D. Leifer, Matthew J. Kelley, Natalie Walsh, Ziba Shahriary, Paul Steinvurzel, Chrissy Fortuna, Geoffrey Maul, Adam Darley, Ian Coddington, Laura C. Sinclair, Ariel Berman, Victor Chin, Henry Timmers, Kevin Knabe, Jason Pinon, Andrew Attar, Cole Smith, Cyrus Bry, Davis S. Kun, Stan Stanev, Nicole Thai, Bennett Sodergren, Daniel Deveraux, Grant Capan, Will McIntyre, Manas Choure

High Energy Physics (Phenomenology)

Internal structure of exotic hadron candidate $f_0$(980) by using fragmentation functions

S. Kumano

High-energy hadron reactions could be appropriate to find exotic evidences in exotic hadron candidates instead of global observables such as masses, spins, parities, and decay widths, because quarks and gluons are explicit degrees of freedom. One of possible methods is to use fragmentation functions (FFs) by taking advantage of properties on favored and disfavored functions, which corresponds to valence-quark and sea-quark distributions in parton distribution functions. Looking at these FFs, we should be able to find the exotic nature as the valence-quark distributions reflect the nature of valence constituents as shown in the pion and the proton. Recent accurate measurements of the $f_0$(980) FFs by the Belle collaboration made it possible to find its internal configuration by looking at their second moments and functional forms. Global analysis results of the $f_0$(980) FFs indicate that its internal configuration looks like $s\bar s$, which is different from a tetraquark or $K\bar K$-molecule like configuration suggested from low-energy studies. This fact indicates that the internal configuration looks different depending on the energy. At low energies, it looks like a tetraquark ($K\bar K$ molecule) hadron, but it looks like a $q\bar q$ hadron at high energies. In the similar way, some exotic hadron candidates could become ordinary $q\bar q$ or $qqq$ hadrons at high energies, although they are interpreted as exotic at low energies. This kind of new idea should be tested by future experiments especially by looking at energy or momentum dependencies in high energy hadron reactions.
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Quantum Physics

The Fourier Uncertainty Principle Through the Lens of Infinite Banded Matrices

Cameron L. Williams, Lara C. Ortelli and Gael Silva

In this paper, we investigate the Fourier uncertainty principle through infinite banded matrices by way of a variational approach to minimizing the uncertainty product. Traditional methods for analyzing the Fourier uncertainty principle rely heavily on the Heisenberg–Weyl structure that underlie the Fourier transform and therefore do not generalize well beyond this setting. We provide three distinct approaches to developing the uncertainty principle based on the spectrum of a shifted quantum harmonic oscillator Hamiltonian, $H_{a,b}$. In the Hermite–Gauss basis, $H_{a,b}$ has an infinite, tridiagonal form which is central to the analysis. One approach exactly solves for the spectrum through analytic methods, another decomposes $H_{a,b}$ into an infinite sum of $2\times 2$ matrices, and the third approach is an algebraic approach to establishing the spectrum via a unitary equivalence with the quantum harmonic oscillator. The approaches taken herein provide alternate avenues that are more broadly applicable to other canonically conjugate operators for other integral transforms which maintain a tridiagonal form.
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Soft Condensed Matter

Prediction of the maximum penetration of a circular intruder in a two-dimensional granular bed from its early trajectory using Machine Learning

Patricia Altshuler

We test whether the maximum penetration depth of a circular intruder into a two-dimensional granular bed can be predicted from its early trajectory using machine learning, without giving the intruder density. From 100 DEM simulations with varying density, we extract kinematic features from the first 50 ms. Ridge and Random Forest predict the maximum penetration. A single feature (the intruder height at 50 ms) concentrates almost all predictive power, showing that density information is already encoded in the early impact response.
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High Energy Physics (Phenomenology)

Nuclear modifications on longitudinal-transverse structure-function ratio $R$ in the deuteron

S. Kumano

In lepton scattering from nuclei, it has been taken for granted that nuclear modifications do not exist for the longitudinal-transverse structure-function ratio $R$, although nuclear effects in $F_2$ have been investigated for a long time. In fact, experimental data of lepton-nucleus scattering have been analyzed with this assumption. It is obviously not appropriate because nuclear modifications exist in the function $R$ theoretically as shown in this work. In this work, we explain nucleon's Fermi motion's effects by using a convolution description for nuclear structure functions, especially on the deuteron. The longitudinal and transverse structure functions are defined by taking the virtual photon momentum direction along the $z$ axis. However, nucleons in a nucleus could move in any direction, so that nucleon's longitudinal and transverse structure functions could mix with each other in the nuclear medium. Such mixing effects could be of the order of $\vec p_\perp^{\,2}/Q^2$, where $\vec p_\perp$ is the nucleon's transverse momentum and $Q^2$ is given by $Q^2=-q^2$ with the virtual-photon momentum $q$, because the transverse Fermi-motion is the source of such a mixture. In addition, nuclear effects are different between the longitudinal and transverse structure functions in the convolution model because their $x$-dependent functional forms are different. Convolution integrals have different results between the longitudinal and transverse structure functions for nuclei. Because the experiment is in progress at the Thomas Jefferson National Accelerator Facility to measure the function $R$ for the deuteron, the numerical results are shown on the nuclear effects of $R$ in the deuteron. Hopefully, such nuclear effects are found experimentally by future experiments including heavy nuclear targets.
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High Energy Physics (Phenomenology)

$D^{(*)}\Delta$ interactions and the molecular interpretation of $\Sigma_c(3200)^0$

Rui Chen, Yu-Yue Cui and Fu-Lai Wang

Inspired by the recent observation of the $\Sigma_c(3200)^0$ baryon in the $\Lambda_c^+\pi^-$ invariant mass spectrum by the LHCb Collaboration, we perform a comprehensive investigation of the $D^{(*)}\Delta$ interactions within the one-boson-exchange framework. Our results show that the $D^*\Delta$ molecule with $I(J^P)=1(1/2^-)$ can be regarded as the most natural candidate for the $\Sigma_c(3200)$, and predict the existence of several $D^*\Delta$ molecular partners with $I(J^P)=1(3/2^-, 5/2^-)$ and $2(1/2^{\pm}, 3/2^{\pm}, 5/2^-)$. After including the coupled channel effects between $D\Delta$ and $D^*\Delta$, several shallowly bound $D\Delta$-dominated molecular candidates also emerge, especially for the $I(J^P)=1,2(3/2^-)$ and the $2(1/2^+,3/2^+)$ systems. These results provide a unified molecular interpretation of the newly observed $\Sigma_c(3200)^0$ and useful guidance for future experimental searches for exotic charmed-baryon states. We expect the high-statistics data from the LHCb Upgrade and Belle~II runs will directly test these predictions.
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Materials Science

Magnetically coupled charge-transport crossover and giant negative magnetoresistance in iodine-incorporated Cr$_2$Se$_3$

Bikash Das, Shibnath Mandal, Kapildeb Dolui et al. (+12 more)

We report the synthesis and comprehensive investigation of iodine-incorporated $Cr_2Se_3$, a non-van der Waals quasi-two-dimensional magnetic material, using structural, magnetic, transport, spectroscopic, and first-principles methods. Magnetization and electron spin resonance measurements reveal an antiferromagnetically ordered state below $T_N \approx 52$ K. At higher temperatures, a second, broader anomaly emerges near $T^* \approx 150$ K, coinciding with a shallow minimum in the temperature-dependent resistivity that resembles a metal-to-insulator-like crossover. Hall measurements indicate predominantly hole-like conduction at high temperatures ($\geq$ 150 K), while the nonlinear Hall response below T*, together with an anomaly in the third-harmonic electrical signal, suggests the emergence of mobility-dependent multichannel and spatially inhomogeneous transport. A large, non-saturating negative magnetoresistance reaching approximately -78% at 25 K and 12 T further demonstrates strong coupling between charge transport and the magnetic state. Temperature-dependent Raman spectroscopy reveals no symmetry-changing structural transition near T*, whereas angle resolved photoemission spectroscopy (ARPES) measurements show no major reconstruction of the electronic structure occupied across the crossover. Taken together, these results identify the high-temperature anomaly as a broad magnetically coupled transport crossover arising from the interplay of short-range magnetic correlations, chemical disorder, and redistribution among competing conduction channels. These findings demonstrate that anion incorporation provides an effective route to tuning the coupled electronic and magnetic properties of non-layered Cr$_2$Se$_3$, establishing this system as a promising platform for investigating correlated transport and emergent spintronic functionalities in transition-metal chalcogenides.
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All authors Bikash Das, Shibnath Mandal, Kapildeb Dolui, Oleksi Laguta, Sambit Choudhury, Suvadip Masanta, Tanima Kundu, Jorge Andres Navarro Giraldo, Alexey Barinov, Shibabrata Nandi, Kai Rossnagel, Sanjoy Kr Mahatha, Rajib Mondal, Petr Neugebauer, Subhadeep Datta

Nuclear Theory

Alpha-cluster Formation and Decay: Four-Body Correlation and Configuration Mixing

Yi Wu and Chang Xu

Alpha-decay provides an important probe of nuclear structure and the underlying nucleon-nucleon interaction, while its rigorous microscopic description from first principles remains challenging. For $\alpha$+magic core systems, a microscopic treatment of $\alpha$-cluster formation and decay has been achieved by considering both the four-body correlation on top of the core and Pauli blocking. Extending this microscopic description to open-shell nuclei should account for the configuration mixing caused by the residual interactions between valence nucleons near the Fermi surface. In this work, we improve the quartetting wave function approach (QWFA) by incorporating the pairing-induced configuration mixing using the particle-number-projected Bardeen-Cooper-Schrieffer (PBCS) method. We find that the pairing enhance the formation amplitudes of the $\alpha$-cluster in open-shell nuclei while the closed shells suppress the $\alpha$-clustering.
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Quantum Physics

Rényi and Tsallis information entropies for a harmonic position-dependent mass

Dorcas A. Addo, Daniel Sabi-Takou, Eugene Adjei et al. (+1 more)

In this paper, we study Renyi and Tsallis information entropies for a Hamiltonian system with position-dependent mass confined in harmonic oscillator potential. Gegenbauer polynomials are used to obtain the position eigenfunction of such a system, and the modified Bessel function of the second kind is used to determine the equivalent momentum eigenfunction. By means of probability densities of both representations, we analytically and numerically evaluate the Heisenberg-like uncertainty of this system. Because the Renyi and Tsallis information entropies in position representation are described by integral functionals of the Gegenbauer polynomials, these quantities are much more difficult to calculate. To get around this problem, we evaluate these information entropies at the system s asymptotical limit, which corresponds to the behavior of an undeformed harmonic oscillator. Nevertheless, no approximation method is used to obtain the Tsallis and Renyi information entropies in momentum representation. In both representations, we find that these information entropies approach the Shannon entropy when the entropic parameter alpha-> 1 and are closed to the results of similar models of the literature. Finally, we evaluate the related entropic uncertainty relations numerically to validate the latter obersevations.
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All authors Dorcas A. Addo, Daniel Sabi-Takou, Eugene Adjei, Latévi M. Lawson