Quantum Physics
Set-Packing and Sequence-Pair QUBOs for the 2D Cutting Stock Problem on Quantum Annealing Hardware
Miguel Sánchez-Beato, Raul Martinez, Matilde Osa et al. (+2 more)
The two-dimensional Cutting Stock Problem (2D-CSP) is an NP-hard problem with direct economic and environmental impacts on manufacturing and logistics. We encode its fixed-plate variant, with free piece repetition and full non-overlap and containment constraints, as a Quadratic Unconstrained Binary Optimization (QUBO) problem for
quantum annealing and compare two formulations from opposite encoding paradigms. The first was a coordinate-based set-packing model with one binary variable per candidate placement. Its variable count grows linearly with plate area and resolution, but its ground state is, by construction, a geometrically feasible maximum-area packing. The second is a coordinate-free sequence-pair model whose variable count is independent of plate resolution and size. We prove that this compactness has a structural limit: no coordinate-free QUBO of bounded interaction degree whose penalties vanish on every geometrically feasible layout can have a geometrically feasible ground state for 2D containment, because containment is a longest-path constraint that bounded-degree penalties cannot enforce on chains longer than their interaction order. We evaluate both formulations under multi-seed simulated annealing, simulated
quantum annealing, and an exact integer-programming baseline. Hardware experiments include D-Wave minor
embedding, a calibrated direct-QPU sweep, and Leap hybrid solvers in both penalty and constraint-native form, across a six-instance campaign with per-instance calibration. The hybrid solver returns our certificate configuration, tying its energy to thirteen decimal places while overflowing the plate. We claim no
quantum speedup. Our contribution is an impossibility result characterizing the limits of compact packing QUBOs, and a practical rule for choosing between the two formulations.
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All authors Miguel Sánchez-Beato, Raul Martinez, Matilde Osa, Jorge Parra, Mario Calonge
Quantum Physics
UCQM: A Six-Metric Quality Framework for Continuous-Variable Cluster States
Saman Sarshar
Continuous-variable (CV) cluster states constitute one of the central resources for measurement-based
quantum computation (MBQC). Despite substantial progress in their theoretical development and experimental realization, comparing the quality of different cluster-state
topologies remains challenging, as existing approaches typically rely either on qualitative inspection of covariance
matrices or on individual metrics that characterize only a single aspect of the underlying correlation structure. In this work, we propose a quantitative evaluation framework that integrates six complementary descriptors of CV cluster states: total correlation strength (SSC), correlation uniformity (CAV), error resilience (EVC), communication overhead (COM), path redundancy (RED), and bottleneck vulnerability (BOT). These quantities are combined into a single Unified Cluster Quality Metric (UCQM), providing a consistent basis for evaluating and comparing different cluster-state architectures. The proposed framework is applied to four-mode path, square, and
star cluster
topologies over the squeezing range $r \in [0.2,1.8]$. Across the investigated parameter regime, the square
topology consistently achieves the highest UCQM score, indicating the most balanced structural characteristics among the
topologies considered and supporting its suitability for measurement-based
quantum computation. Because all six metrics are derived directly from covariance-
matrix elements together with graph connectivity, the framework naturally extends to arbitrary $N$-mode cluster states, higher-dimensional
lattice geometries, and experimentally reconstructed covariance
matrices. Beyond providing a single numerical score, UCQM offers a unified perspective for analyzing the structural quality of CV cluster states and establishes a practical framework for their systematic comparison, optimization, and future design.
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Soft Condensed Matter
The hypoexponential form for the fiber-length distribution in thermoplastic composites revisited: finite initial length, cascade fracture, and its mechanistic status
Yuichi Masubuchi
In a previous work [Masubuchi et al., Compos. Sci. Technol. 134, 43 (2016)], a fiber-length distribution function was proposed as the hypoexponential, or Erlang-type, convolution of two exponential waiting lengths, motivated by two independent Poisson processes for breakage and for blocking of adjacent breaks. The present paper further evaluates this hypoexponential form by introducing a finite initial length L_{0}, and by analyzing the mechanistic basis of the buckling-induced fiber breakage process. The obtained finite-L_{0} closed-form solution was compared to a glass fiber
dataset to retroactively justify the infinite-length idealization in the earlier work for such systems while providing the complete form for processes in which fragments remain comparable to L_{0}. Concerning the mechanics of fiber fragmentation, a Mellin transform analysis of the fragmentation equation showed that scale-invariant cascades yield power laws and therefore cannot generate characteristic lengths; those lengths must instead arise from scale-breaking ingredients, particularly the cutoff region and the arrested processing history. Monte Carlo simulations of a phenomenological finite-opportunity cascade showed that the hypoexponential form does not reproduce the peak of the generated distribution but captures its exponential-like tail, implying that it serves as a useful two-parameter fitting model, although not an exact generative distribution.
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Medical Physics
Impact of Multiple Non-Invasive Biosignals on Cardiovascular Biomarker Estimation via Simulation-Based Inference
Shusaku Maeda, Masahiro Nakano, Tomoharu Iwata et al. (+3 more)
As the population ages, the number of patients with cardiovascular diseases continues to increase, highlighting the need for early detection before progression to severe and irreversible functional decline. Consequently, estimating cardiovascular biomarkers from non-invasive biosignals, such as photoplethysmography (PPG) and arterial pressure wave (APW) signals, has attracted increasing
attention. These signals can be measured using wearable and cuff-type devices. Previous studies have used PPG and APW signals to estimate cardiovascular biomarkers. However, these signals exhibit strong similarities in both the temporal and frequency domains and primarily reflect peripheral and arterial pulse waveforms. Therefore, they may provide limited information about cardiac mechanical function. In contrast, the quantitative impact of additional biosignals, such as ballistocardiography (BCG), which reflect the body's minute mechanical responses to cardiac ejection, remains unclear. In this study, we generated synthetic PPG, APW, and BCG signals from a unified whole-body cardiovascular circulation model and evaluated the complementary contribution of BCG to probabilistic cardiovascular biomarker estimation. We estimated posterior distributions of cardiovascular biomarkers using neural posterior estimation and simulation-based inference. The results showed that adding BCG signals significantly improved estimation performance. Furthermore, even in ill-posed cases where PPG and APW alone produced
multimodal posterior distributions, adding BCG yielded unimodal posterior distributions. These findings provide fundamental insights into signal selection for estimating cardiovascular dynamics.
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All authors Shusaku Maeda, Masahiro Nakano, Tomoharu Iwata, Kenji Komiya, Ryo Nishikimi, Kunio Kashino
General Physics
Green's function of non-Hermitian systems at exceptional deficiency
Congwei Lu and Guancong Ma
Exceptional deficiency is a newly discovered broadband non-Hermitian condition, at which the system's spectrum is entirely composed of exceptional points and all eigenvectors pairwise coalesce. Here, we analyze the steady-state and time-domain responses of non-Hermitian
lattices at exceptional deficiency by considering their frequency and time-domain Green's functions. We show that the frequency-domain Green's functions are characterized by the emergence of second-order poles across the entire spectrum, producing broadband second-order super-Lorentzian line shapes, enhanced magnitude, and sequential 2pi phase shifts across each resonance. These second-order poles also underpin unconventional responses to global dissipation, by which we uncover a loss-revival of defective skin effect: the skin modes that are "missing" due to the system's defectiveness at exceptional deficiency can re-emerge in the responses. In the time-domain responses, a linear-in-time amplification factor is identified in the
evolution kernel, which can enhance skin-effect dynamics that would otherwise be suppressed by global loss. The amplification strength scales with the degree of defectiveness of the system and diminishes upon spectral detuning between subsystems. Our work establishes a theoretical framework for analyzing steady-state and dynamic signatures of exceptional deficiency, and opens new routes for dissipation-controlled broadband exceptional responses.
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Fluid Dynamics · Cross-listed from cs.CE
Verification, Sensitivity, and Operating Limits of a GPU-Accelerated Planar WCSPH Model for Hydrodynamic Ram
Md Mujahid Alam, Debojit Biswas and Sukanta Chakraborty
Hydrodynamic ram (HRAM) loading remains a persistent challenge in impact mechanics, less due to exotic physics than to the difficulty of achieving convincing quantitative agreement in reduced-order representations. Prevailing studies typically employ a single mesh and boundary treatment validated against one experimental
dataset, leaving unresolved whether agreement reflects genuine fidelity or compensating discretization errors. This work presents a planar 2D, GPU-accelerated WCSPH solver employing an Adami-type ghost-particle boundary condition, extended for the first time to a moving, decelerating disk penetrating a confined
liquid channel at ballistic velocity. The boundary condition is examined against a purpose-derived potential-flow added-mass solution and the analytical acoustic reflection coefficient at the steel-water interface; this exploration reveals that the stiff equation of state and cavitation cutoff impose identifiable delineation of the solver's operating regime on quantitative agreement. A three-point resolution convergence study reveals a non-monotone near-probe pressure peak, attributed to a bounded ghost-fluid density inconsistency. A comprehensive coefficient sweep, conservation diagnostics, and O(N) GPU throughput scaling enable exhaustive characterization impractical in 3D. Qualitative comparison against literature evidence at 900 and 600m/s clarifies load bearing versus approximate elements. Notably, energy diagnostics reveal a modest total energy growth over the simulated window, with the fluid absorbing disproportionately more energy than the projectile relinquishes - an instructive signature of prescribed, non-back-reacting projectile kinematics that helps map the formulation's operating envelope. The resulting solver, while confined to planar geometry, delivers verified, convergence-checked performance well suited for rapid parametric design exploration.
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Applied Physics · Cross-listed from cs.NE
Optimizing Train Driving to Minimize the Electricity Cost of an Entire Railway Traffic Mesh using Evolutionary Algorithms
Eduardo Pilo de la Fuente, Sudip K. Mazumder and Maria Antonia Simon
This paper presents a procedure to optimize the way trains are driven, which pursues, in addition to fulfilling operational constraints such as admissible speeds or journey durations, the minimization of the cost related to supplying electrical energy to the trains, including the cost of the energy consumption and the cost of the power capacity utilization. This procedure combines: (i) a traffic model that merges the energy and power footprint of each rail service part of the traffic mesh, and (ii) an evolutionary computation framework that enables searching for the optimal way to drive the trains to achieve an optimal traffic mesh. This procedure is applied to a 450 km long section of the high-speed line from Madrid to Barcelona (Spain).
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Soft Condensed Matter
Beyond Crease Geometry: Multistability in Origami-Inspired Structures through Local Fold Architectures
Sagi Senderovich, Ezra Ben-Abu, Shai Elbaz et al. (+3 more)
Origami-inspired tubular structures provide a versatile platform for shape morphing, with multistability achieved predominantly through crease-network geometry. Expanding the range of morphing behaviors can therefore require increasingly intricate crease patterns that become more difficult to model and fabricate, ultimately constraining the realizable morphing landscape. Here, we expand the design space of origami-inspired structures beyond geometry by introducing localized instabilities within the crease network, thereby creating compliant multistable structures whose local fold architectures govern global deformation and stability through both constitutive mechanics and
geometric constraints. To relate local fold architectures to global multistability, we develop and experimentally validate a modeling framework in which compliant folds are represented as continuous fields that capture spatially varying bistable mechanics. Force- and displacement-controlled design maps demonstrate that global deformation and stability can be programmed through the fold architecture's local parameters. Redistributing bistability within a fixed crease-network
topology shifts the global response between compliant, spatially distributed deformation in semi-bistable architectures and discrete transitions within a hierarchically organized space of stable configurations in fully bistable architectures. These results establish a local-to-global design principle for programming both the stable configurations of a structure and the transition pathways connecting them, expanding the design space for multistable metamaterials, adaptive morphing structures, and soft robotic systems.
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All authors Sagi Senderovich, Ezra Ben-Abu, Shai Elbaz, Nadav Zemah, Anna Zigelman, Amir Daniel Gat
History and Philosophy of Physics
The Surviving Fragment of the Zij-i Malikshahi: A Preliminary Edition, Translation, and Study of the 100-Star Catalogue in BnF Arabe 5968
Rizoi Bakhromzod
The astronomical programme sponsored by the Saljuq Sultan Malikshah I in the late eleventh century occupies an important place in the history of Islamic astronomy. Umar Khayyam was a principal participant in this programme, which produced the Jalali or Maliki calendar and appears also to have resulted in a broader set of astronomical tables known as the Zij-i Malikshahi. A 100-
star catalogue traditionally associated with these tables survives in the anonymous Arabic compendium Dustur al-munajjimin, preserved in the unique manuscript BnF Arabe 5968. This study distinguishes the catalogue from the Jalali calendar and from the lost or unidentified complete Zij-i Malikshahi, reconstructs its historical and manuscript context, and examines the provenance of BnF Arabe 5968. It presents a complete transcription of the catalogue from fols. 224r-225r and a new English translation made directly from the Arabic text, with B. A. Rosenfeld's 1961 Russian translation used as a control. The collation identifies several divergences, including a substantive correction to the longitude of entry 8, and clarifies the planetary temperament abbreviations. Rosenfeld and A. P. Yushkevich observed that 96 of the 100
stellar longitudes correspond to Ptolemaic values increased by about 14 degrees 26 minutes, while 87 latitudes agree with Ptolemy. These correspondences suggest systematic updating of inherited Ptolemaic data rather than 100 wholly independent observations, illustrating the combined roles of observation, computation, transmission, and adaptation in medieval Islamic astronomy.
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Physics and Society · Cross-listed from q-bio.NC
Inverse planning of social interactions in relationships
Alicia M. Chen, Ashley J. Thomas, Joshua B. Tenenbaum et al. (+1 more)
We propose a formal account of how structured, shared knowledge about social relationships shapes action interpretation. The model represents relationships as constraints in a social environment, analogous to boundaries or obstacles in a physical environment and operating within the same generative model, but exerting distinct constraints on action. As an initial test of this framework, we draw on research across the social sciences to capture in the models how one dimension of relationships – formality versus intimacy – shapes how people interpret interpersonally vulnerable behavior. We test this account in stories of naturalistic everyday situations, extending structured models of action understanding to open-ended contexts. Across six preregistered experiments (N = 1,554), the model captures people's inferences about desires, physical environments, and social relationships. This work formalizes how relationships can constrain – and be revealed through – everyday action.
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All authors Alicia M. Chen, Ashley J. Thomas, Joshua B. Tenenbaum, Rebecca Saxe
Data Analysis and Statistics
Geometry-native machine learning reconstruction of DSMC moment fields with support monitoring
Ehsan Roohi
Direct simulation Monte Carlo (DSMC) resolves rarefied-gas dynamics without a constitutive closure, but finite-sample estimates of macroscopic moments converge at markedly different rates. We develop a non-intrusive, geometry-native machine learning reconstruction of the retained two-dimensional moment hierarchy: number density, two velocity components, translational temperature, three pressure-tensor components, and two heat-flux components. From three sampling blocks, the
estimator corrects a structured prior learned from development data with a bounded term computed from the current observation, while preserving additive-moment consistency and the measured zero-frequency content. In cavity development tests, the final observation-conditioned
estimator, whose prior is a trained MambaIR restoration network, reduces transverse-heat-flux error to 0.658 and 0.672 times that of a ten-block direct average at two rarefied conditions. For a hypersonic cylinder, a cylinder-centred
estimator is fixed before evaluation on six new observation/reference pairs. It improves both global transverse heat flux and near-wall normal heat flux in every pair; the ratios of arithmetic-mean normalised root-mean-square errors (NRMSEs) are 0.846 and 0.793, and the Holm-adjusted one-sided exact probabilities are 0.03125.
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General Physics
Thermodynamics of four-dimensional Einstein-Gauss-Bonnet black holes with a modified temperature
Sergio Noboru Yuzuka
We compare two thermodynamic prescriptions associated with the same static, spherically symmetric four-dimensional Einstein-Gauss-Bonnet anti-de Sitter black hole. Model A uses the usual Hawking temperature obtained from the surface
gravity and consequently yields an
entropy with a logarithmic correction. Model B preserves the shift
symmetry of the scalar field at the level of the thermodynamic charges, recovers the Bekenstein-Hawking area law, and requires a modified temperature for consistency with the first law. We derive the equations of state, Gibbs free energies, heat capacities, and critical quantities of both prescriptions in the extended phase space. The two models display the same qualitative Van der Waals phase structure, but their critical scales and local stability regions differ quantitatively. In the uncharged case, Model A has a larger critical horizon radius and lower critical temperature and pressure than Model B.
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High Energy Astrophysical Phenomena
G(2) Glueball Boson Stars as Restricted Kerr Mimickers in the Thomas–Fermi Limit
Nicolò Masi
We investigate whether horizonless compact
stars made of dark glueball matter from a broken exceptional $G(2)$ gauge sector can reproduce selected Kerr observables within a Thomas–
Fermi effective-fluid description. We introduce GC9, a scale-separated $G(2)$-inspired positive nonic-density closure whose high-density stiffness, bag-free surface and Q-ball safety make it a useful compact-
star benchmark. After Thomas–
Fermi rescaling, reduced
stellar observables are independent of the microscopic glueball mass $m_G$, while the collective stiffness $\Lambda_T$ fixes the dimensional mass and radius. Solving the TOV, Hinderer and Hartle–Thorne systems, we obtain a stable maximum-mass compactness $C=0.3247$,
tidal deformability $\Lambda=4.37$, $\bar I C^{3/2}=0.947$, and slow-rotation quadrupole $\bar Q=1.522$. At $j=0.328$, the same-order ISCO shift is $1.24\%$. The stable endpoint has no light ring, but its exterior Regge–Wheeler barrier supports a genuine static axial mode, $M\omega=0.463846-0.098881i$, with a damping time about ten percent shorter than Schwarzschild and a real frequency $24.1\%$ higher. A polarization-balanced vector realization has the same isotropic bulk EOS; moderate residual anisotropy changes static and first-order observables only at the few-percent level, while the full coupled vector spectrum remains open. Cowling calculations identify matter-supported quadrupolar modes. The scalar-burst, seeded-collapse and cosmological sections are phenomenological: a fixed $\Lambda_T$ gives a compact Kerr-comparison branch only near its own maximum mass, so the multi-sector scenario assumes distinct constant-$\Lambda_T$ branches from the keV supermassive sector to the PeV asteroid-mass sector. GC9 therefore defines a falsifiable restricted Kerr-mimicry framework for gravitational-wave, horizon-scale and compact-dark-matter tests.
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Computational Physics · Cross-listed from math.NA
A Framework Integrating the Dynamic Stiffness Matrix with Physics-Informed Neural Networks for Solving Eigenvalue Problems and Analysing Dynamic Response
Yi An, Zhijiang Chen, Zhiqiang Feng et al. (+4 more)
This paper introduces a framework that integrates the dynamic stiffness
matrix (DSM) with physics-informed neural networks (PINN). The DSM-PINN embeds physical constraints within the model and demonstrates robustness, particularly when addressing limited
datasets across diverse investigations. In this approach, deep neural network outputs approximate the displacement fields of element nodes. Unlike the finite element method (FEM), the element shape functions are homogeneous solutions to the governing partial differential equation, forming the basis of the exact dynamic stiffness
matrix, thereby avoiding high-order derivative terms. This
matrix also serves as a frequency-domain spectral element, resulting in a strong-form PINN. The loss function is produced by connecting neural networks with dynamic stiffness
matrices. We focus on utilising PINNs to resolve
eigenvalue problems by employing the Wittrick-Williams
algorithm, which overcomes the challenge of neural networks failing to converge to higher-order
eigenvalues. Additionally, the frequency domain-PINN method is used to analyse structural dynamic responses under moving and impulsive loads, addressing the limitation of neural networks in handling complex numbers. Theoretical convergence stability of the suggested approach is also analysed even DSM is an indefinite
matrix after implementing the boundary condition. The numerical results validate the practicality and efficacy of the recommended approach.
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All authors Yi An, Zhijiang Chen, Zhiqiang Feng, Qian Cheng, Jack C.P. Cheng, Haijiang Li, Dalei Wang
Fluid Dynamics
Fluxes through a uniform double-diffusive staircase at low Prandtl number
Arstanbek Tulekeyev and Pascale Garaud
Double-diffusive convection in the diffusive regime is often observed to be in a long-lived layered state, well-known in the Arctic ocean and in volcanic lakes, and thought to exist in the interiors of
giant planets. The density profile resembles a `staircase', with stacks of convective layers of uniform density separated by strongly stratified interfaces. The governing parameters are the Prandtl number $\mathrm{Pr}$, diffusivity ratio $\tau$, density ratio $R_\rho$, and Rayleigh number $\mathrm{Ra}$. In this work, we perform direct numerical simulations in triply periodic domains to systematically investigate the properties of statistically stationary double-diffusive staircases with $\tau \le \mathrm{Pr} \ll 1$. We demonstrate that they can exist for significantly larger density ratios than previously reported, and propose a new criterion for the existence of long-lived layered states. Notably, this criterion depends weakly on $\mathrm{Ra}$. In all simulations, we measure the total fluxes of density $F^{\mathrm{tot}}_\rho$, temperature $F^{\mathrm{tot}}_T$ and composition $F^{\mathrm{tot}}_C$, and the flux ratio $\gamma =F^{\mathrm{tot}}_C/F^{\mathrm{tot}}_T$. We confirm that $\gamma$ is approximately constant for moderate to large $R_\rho$ but also depends weakly on $\mathrm{Ra}$. We show that the Nusselt numbers for composition and temperature scale as $\mathrm{Ra}^{1/3}$ in this limit, which notably differs from the $(\mathrm{RaPr})^{1/3}$ scaling previously found at lower $R_\rho$. We propose a new model for these findings that is based on the rise and turbulent mixing of density anomalies that form at the edges of the interfaces. The model explains the existing low $\mathrm{Pr}$ data with reasonable accuracy.
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Materials Science
Nucleation and propagation of brittle fracture as a constrained energy minimization problem
Oscar Lopez-Pamies, Farhad Kamarei, Gilles A. Francfort et al. (+1 more)
This paper presents a macroscopic, or continuum, theory aimed at describing when, where, and why cracks nucleate and propagate in nominally elastic brittle materials under monotonic, quasi-static, but otherwise arbitrary mechanical loads. Motivated by recent insights, the proposed sharp theory posits that: cracks nucleate and propagate exclusively in regions where the strength surface of the material is exceeded, with their
evolution dictated by the minimization of the sum of the potential — the elastic energy minus the work done by the externally applied forces — and surface energies. While the theory applies to materials with any elasticity (linear or nonlinear) and any material
symmetry (isotropic or anisotropic),
attention is restricted here to the most basic case of isotropic elastic brittle materials. For demonstration purposes, the theory is confronted with a set of nine tests that span the entire range of well-settled experimental knowledge on fracture nucleation and propagation — the so-called “Nine Circles of Elastic Brittle Fracture” — on both a hard material (a silicate glass) and a soft material (a synthetic rubber).
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All authors Oscar Lopez-Pamies, Farhad Kamarei, Gilles A. Francfort, Alessandro Giacomini
Plasma Physics
Anisotropic Maxwell neural operator for rapid parametric full-wave modelling of ion cyclotron resonance heating
Heng Zhang, Xu Wang, Jiayi Li et al. (+6 more)
Full-wave calculations of ion cyclotron resonance heating (ICRH) under different
plasma dielectric conditions require repeated assembly and solution of large-scale discretised systems, limiting parameter sweeps and multi-case response analysis. We therefore propose an anisotropic Maxwell neural operator (AMNO) for rapid parametric modelling of ICRH full-wave responses for the Experimental Advanced Superconducting Tokamak (EAST), which learns, within the one-parameter dielectric-field family generated by varying the hydrogen minority fraction X_H over 0.01-0.05 under otherwise fixed settings, a shared solution operator from the spatially varying complex anisotropic dielectric-tensor field to the three-component complex electric field under frequency-domain Maxwell constraints. It represents global spatial coupling through spectral operator layers and local fine-scale responses, and combines sparse reference-field supervision with the frequency-domain Maxwell-equation residual. Comparisons with COMSOL reference solutions for the same EAST frequency-domain Maxwell-dielectric model show that AMNO reconstructs the principal spatial and spectral features and maintains stable accuracy for unseen interpolation test cases. With reference-field points reduced to 7.5% of the dense full-wave set, AMNO reduces the relative L_2 error by 66.1%-89.9% compared with a sparsely supervised
Fourier neural operator (FNO-Sparse) under the same supervision and requires about 0.25 s for single-case inference. AMNO thus reduces dependence on dense reference-field supervision while enabling subsecond parametric complex-field inference, providing a physics-constrained and data-efficient surrogate for rapid in-range X_H sweeps and cross-case response analysis within the modelled EAST configuration.
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All authors Heng Zhang, Xu Wang, Jiayi Li, Miao Zhang, Jiahui Zhang, Kaihao Wang, Yangdi Yi, Qin Hang, Xinjun Zhang
General Relativity and Quantum Cosmology
Gödel-type universes in Lorentz-violating Kalb-Ramond gravity with Ricci- and Riemann-tensor nonminimal couplings
Fernando M. Belchior
This paper studies homogeneous \Godel-type geometries in a gravitational model where local Lorentz
symmetry is spontaneously broken by the
vacuum expectation value of an antisymmetric Kalb-Ramond two-form. We consider the Einstein-
Hilbert action supplemented by two independent nonminimal
curvature couplings: a
Ricci-tensor coupling of the form $B_{a}{}^{c}B_{bc}R^{ab}$ and a Riemann-tensor coupling of the form $B^{ab}B^{cd}R_{abcd}$. In the homogeneous
vacuum sector, where the Kalb-Ramond field strength and the first derivatives of the
symmetry-breaking potential vanish, the field equations reduce to a closed algebraic system in the tetrad frame of the \Godel-type metric. We derive the
curvature tensors, the reduced metric equations, and the Kalb-Ramond consistency equations for several inequivalent orientations of the
vacuum two-form. Particular
attention is given to the pseudo-
magnetic background $B_{12}=b$, because it preserves the
symmetry of the rotation plane and yields a transparent deformation of the usual bumblebee result. For this sector the Kalb-Ramond equation fixes $\frac{m^2}{\omega^2}=\frac{2(\xi_1+3\xi_2)}{\xi_1+2\xi_2}$, where $\xi_1$ and $\xi_2$ are the
Ricci and Riemann couplings. The
Ricci coupling alone reproduces the noncausal \Godel value $m^2=2\omega^2$, while the Riemann coupling shifts the chronology bound and allows the critical causal value $m^2=4\omega^2$ for $\xi_2=-\xi_1$. We also show that the Riemann coupling can move the critical radius for closed timelike curves, but ordinary positive-energy matter severely restricts completely causal solutions. Finally, we discuss perfect fluid, scalar field, and electromagnetic sources.
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Statistical Mechanics
Fluctuation–response relations from an emergent $\mathbb{Z}_2$ symmetry in the rotating stochastic Landau model
Dhruv Kush, Nicki Mullins, Mauricio Hippert et al. (+1 more)
In this work, we investigate the extent to which fluctuation–response relations emerge from coarse-grained
stochastic dynamics alone, and which aspects instead depend on additional information about the system. To address this question, we study the rotating
stochastic Landau model, an exactly solvable system describing an overdamped charged Brownian particle in a constant
magnetic field, coupled dissipatively to a rotating environment, whose steady state supports circulating probability currents. Using the Martin–Siggia–Rose path integral, we show that there is an emergent $\mathbb{Z}_2$
symmetry transformation that implements the time-reversed dynamics and changes the action by a boundary term. Comparison with the Crooks fluctuation
theorem identifies this term with the
entropy associated with transitions between steady-state configurations. After coupling the theory to external sources, the same
symmetry yields Ward identities relating fluctuations and response. These identities follow entirely from the coarse-grained
stochastic theory and do not fix the noise strength. Finally, upon imposing the Einstein relation, we show that they coincide with the high-temperature fluctuation–dissipation relations implied by the rotating Kubo–Martin–Schwinger condition for a microscopic Gibbs ensemble.
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All authors Dhruv Kush, Nicki Mullins, Mauricio Hippert, Jorge Noronha
High Energy Physics (Phenomenology)
Direct and Indirect searches for DM-electron interactions in sub-GeV DM models
Marco Cirelli, Arpan Kar, Antoine Letessier-Selvon et al. (+1 more)
We analyze the complementarity between direct detection (DD) and indirect detection (ID) searches of sub-GeV dark matter (DM) in the context of two realistic models: the vector-portal (dark
photon) and scalar-portal (
higgs-portal) models. For DD we focus on the latest constraints on the DM-electron scattering from the present DAMIC-M experiment as well as its future projection. For ID we consider several existing X-rays/gamma-rays and
cosmic-ray ($e^\pm$) observations as well as the upcoming MeV
telescope COSI to obtain the corresponding bounds and projections on the DM annihilation rate, which are then translated in terms of the DM-electron scattering cross-section and compared with the DD bounds/projections. We properly take into account astrophysical and
galactic propagation uncertainties. We find that the complementarity between DAMIC-M and ID works best for the vector-portal model, especially for the case where the vector mediator is heavier than the DM particle: in this case, the present DAMIC-M bound becomes comparable to (or better than, for some astrophysical configurations) the combined ID limit for $3\,{\rm MeV} \lesssim m_{\rm DM} \lesssim 20\,{\rm MeV}$. For other cases and mass ranges, the ID is in general more constraining and can also, for some mass ranges, constrain the parameter space below the
neutrino floor, which is inaccessible to DD experiments.
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All authors Marco Cirelli, Arpan Kar, Antoine Letessier-Selvon, Harrys Lumengo-Kidimbu
Optics
HoloCMA: A Holographic Eye on Coarse-Mode Aerosols
Nikil Krishnakumar, Ryne A. Juidici, Nicholas Bravo-Frank et al. (+8 more)
Coarse-mode aerosols (CMAs), including pollen, spores, and
dust, remain difficult to characterize in situ because conventional instruments rarely resolve particle geometry and number concentration together. We present HoloCMA, which combines digital inline holography, numerical reconstruction, and deep learning-assisted analysis for particle-resolved measurement. Its optical system targets particles from approximately 5.0 um to the millimeter scale. HoloCMA supports active sampling at up to 30.0 L/min and converts to open-path operation by removing the sampling module. With an NVIDIA GeForce RTX 5070 Laptop GPU and 8 GB VRAM, HoloCMA reports equivalent circular diameter (ECD) and number concentration in real time without sustained queue buildup up to 11.4 particles/cm3. Additional computing could extend real-time analysis to the workflow limit of 100.0 particles/cm3. We evaluated HoloCMA using polystyrene latex spheres, sodium chloride and ammonium sulfate
crystals, and oleic acid droplets with nominal diameters of 4.9-11.8 um, with an Aerodynamic Particle Sizer (APS) for comparison. Across 12 comparisons, absolute differences between HoloCMA and corrected APS
geometric-mean diameters ranged from less than 0.1 to 1.0 um, with a mean absolute difference of 0.5 um and a mean absolute relative difference of 8.4%. HoloCMA measures
geometric size directly from reconstructed contours, whereas converting APS aerodynamic diameter requires material-specific assumptions. The APS-to-HoloCMA concentration ratio generally decreased with particle size, consistent with size-dependent transport and counting losses in the APS, although the cause could not be determined conclusively. HoloCMA thus enables continuous CMA measurements that combine
geometric size, number concentration, and retained particle images, supporting classification and long-term atmospheric, environmental, and indoor-air monitoring.
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All authors Nikil Krishnakumar, Ryne A. Juidici, Nicholas Bravo-Frank, Shibo Wang, Qisheng Ou, Francisco J. Romayb, Wing Lai, Chongai Kuang, Naruki Hiranuma, David Y.H. Pui, Jiarong Hong
Astrophysics of Galaxies
A radio continuum view of Stephan's Quintet: age, dynamics and origin of the shock
K. Rajpurohit, E. O'Sullivan, G. Schellenberger et al. (+10 more)
We present a detailed, multi-band
radio continuum study of the compact
galaxy group Stephan's Quintet (HCG 92). We use a combination of new (MeerKAT, uGMRT) and archival (LOFAR, VLA) observations covering the $\rm 120\,MHz{-}8\,GHz$ frequency range to examine the
radio properties of the group, focusing on the famous
radio ridge and surrounding diffuse emission. We find filamentary substructure and branching in the southern half of the ridge, confirm an extension of the ridge to the northwest, and identify for the first time a
radio counterpart to the gas bridge linking the ridge and NGC 7319. The northern ridge, northwest extension and diffuse emission have relatively steep, curved spectra, with a high-frequency spectral index gradient running north-south along the ridge. We show that the ridge emission primarily arises from a single physical mechanism, probably strong ($\mathcal{M}\simeq 40-100$) shocks in cold gas, caused by the $\rm \sim850-1000\,kms^{-1}$ collision between NGC 7318B and
tidal gas filaments produced by past
galaxy interactions. Synchrotron spectral age estimates suggest the collision began at the north end of the ridge $\rm \sim20\,Myr$ ago, and finished only $\rm \sim5-6\,Myr$ ago in the south, with the southern end of the shocked ridge likely still within or close to the disk of NGC 7318B. Based on this age gradient, we find that the angle between the intruder
galaxy's motion and the
tidal filaments was probably only about 15 degrees, and combining this with the lack of a spectral index gradient in the diffuse
radio emission suggests that NGC 7318B's direction of motion is probably close to the line of sight.
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All authors K. Rajpurohit, E. O'Sullivan, G. Schellenberger, A. Botteon, R. J. van Weeren, U. Lisenfeld, J. M. Vrtilek, L. P. David, S. Giacintucci, W. Forman, C. Jones, C. K. Xu, A. Togi
Soft Condensed Matter
Comparing non-local granular fluid continuum models for silo discharge: Toward clogging prediction
Y. Zhou, Y. Wang, M. Li et al. (+1 more)
Non-local constitutive theories have received increasing
attention in continuum descriptions of granular flows. However, these models have not been systematically compared for silo discharge within a unified numerical framework. We address this gap with two-dimensional finite-volume method (FVM) simulations of silo discharge using the Basilisk platform. We first validate our FVM implementation of the dynamic non-local granular fluidity (NGF) model against the material point method results of Dunatunga & Kamrin (J. Fluid Mech., 2022, 940, A14), obtaining quantitative agreement. Second, we relate the discharge rate $Q$ to the outlet-to-particle size ratio $D/d$ and the non-local amplitude $A$. From the simulated $Q$, we then evaluate the clogging probability $J(D/d, A)$ within the probabilistic framework of Janda et al. (Europhys. Lett. 84 (4), 44002). The predicted $J$ decays exponentially with $D/d$, consistent with the experimental trend of Janda et al. (Europhys. Lett. 84 (4), 44002). Rather than directly predicting flow arrest, our approach captures the continuous probabilistic transition. Finally, within the same numerical framework and using identical values of $A$, we compare several non-local constitutive models, including several linearised variants that we derive. Almost all models predict a reduction in the discharge rate with increasing $A$, yet significant quantitative differences are observed among the models. The results are further classified into groups according to their predicted flow behaviour, revealing close correspondences among certain formulations. Notably, using the non-local amplitudes reported in the literature [Bouzid et al. (Phys. Rev. Lett. 111, 238301), Henann & Kamrin (Proc. Natl Acad. Sci. USA 110(17))] yields near-zero discharge rates. Ill-posed issues are discussed. The implementation of all models is open-sourced and computationally efficient.
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All authors Y. Zhou, Y. Wang, M. Li, P.-Y. Lagrée
Astrophysics of Galaxies
Systematic uncertainties on DESI Tully-Fisher distances constrained with Integral Field Spectroscopy
Utsav Siwakoti, Lluis Galbany, Kelly A. Douglass et al. (+40 more)
The Tully–Fisher (TF) relation is an empirical tool for estimating distances to spiral
galaxies. The Dark Energy Spectroscopic Instrument (DESI) Peculiar Velocity (PV) Survey uses `tractor' photometric position angles to place fibers along the
galaxy's semi-major axis and infer maximum rotational velocities for $\approx$ 53,000 spirals. Systematic errors arise if the photometric PA differs from the kinematic PA from velocity fields. We quantify systematic uncertainties in DESI-TF distance estimates from photometric PAs and assess the impact of photometric–kinematic PA misalignments. We analyze 215 nearby
galaxies from the PISCO and AMUSING surveys, estimating maximum rotational velocities at $0.4\,R_{26}$ for consistency with DESI-PV. Kinematic parameters are derived using `PaFit' from `Cappellari Software'. Global photometric parameters rely on Siena
Galaxy Atlas SGA-2020 `tractor' data, with `HostPhot' as an alternative approach. Approximately $28\%$ of our sample exhibit photometric–kinematic PA misalignments $>10^\circ$. The median bias in distance is $\approx +1.98\,\mathrm{Mpc}$ with a skewed residual distribution of outliers. The overall distance standard deviation is $19.35\,\mathrm{Mpc}$, with misaligned
galaxies showing twice the dispersion of aligned ones. The Mean Percentage Error is $2.8\% \pm 1.96$ (SE). High
galaxy-to-
galaxy scatter appears in DESI-TF distances, particularly for misaligned systems. Because DESI-TF targets lack kinematic PA measurements, we recommend a global fractional uncertainty of $\approx 3.5\%$. When kinematic information is available, aligned
galaxies with offsets $<10^\circ$ are consistent with $\approx 1\%$ uncertainty, while strongly misaligned or incomplete systems warrant an upper threshold of $\approx 10\%$.
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All authors Utsav Siwakoti, Lluis Galbany, Kelly A. Douglass, Ariel J. Amsellem, Benjamin A. Weaver, J. N. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. de la Macorra, P. Doel, S. Ferraro, J. E. Forero-Romero, E. Gaztanaga, S. Gontcho A Gontcho, G. Gutierrez, C. Hahn, K. Honscheid, C. Howlett, D. Huterer, R. Joyce, S. Juneau, R. Kehoe, T. Kisner, A. Kremin, M. Landriau, L. Le Guillou, M. Manera, R. Miquel, J. Moustakas, S. Nadathur, W. J. Percival, I. Perez-Rafols, F. Prada, G. Rossi, E. Sanchez, D. Schlegel, R. Sharples, J. H. Silber, D. Sprayberry, G. Tarle, H. Zou
Mathematical Physics
Quantum cellular automata and invertible phases of matter
Corey Jones, Nikita Sopenko and Ryan Thorngren
We introduce and study (fermionic and bosonic) invertible quasi-local
algebras over uniformly locally finite metric spaces $X$ with infinite-dimensional local von Neumann
algebras. We show that the group of Brauer equivalence classes of such
algebras is isomorphic to both the group of phases of invertible states and the group of stable equivalence classes of
quantum cellular automata over $X\times \mathbb{Z}$. Using K-theory of the symmetric monoidal category of invertible quasi-local
algebras and bounded spread isomorphisms, we propose a definition of an $\Omega$-spectrum of invertible phases as conjectured by Kitaev. We then show that the $c=\frac{1}{2}$
chiral Majorana
fermion net and the $(E_{8})_{1}$ conformal net provide Brauer non-trivial invertible quasi-local
algebras, thus providing explicit constructions of non-trivial invertible states and
quantum cellular automata on $\mathbb{Z}^{2}$. In addition, we show that the time-slice nets of rational diagonal conformal field theories admit
lattice degrees of freedom, which implies the discretization of any holomorphic conformal net is invertible.
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Geophysics
Global Prevalence of Anti-similar Earthquakes at Intermediate Depth
Albert Leonardo Aguilar Suarez, Gregory Beroza, William Ellsworth et al. (+2 more)
Anti-similar earthquakes, those with nearly identical but flipped waveforms, remain an uncommon observation. We document three locations where these events occur at intermediate depth. The first of these is Colombia, including the well-established source of anti-similar events in the Bucaramanga Nest, and new reports in other intermediate depth seismicity clusters in the Wadati-Benioff zones of Colombia. The second is the Alaska subduction zone, and the third is the Vrancea seismic nest in Romania. These new observations, combined with reports from Japan and Chile, provide mounting evidence that anti-similar earthquake sequences might be a common or characteristic process of intermediate-depth seismicity. Either conjugate faulting promoted by eclogitization induced stresses or sub-parallel faulting can explain their occurrence at these depths. Careful examination of seismicity in other productive intermediate depth seismicity zones might reveal an even more widespread geography for anti-similar earthquakes and place tighter constraints on their underlying mechanism.
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All authors Albert Leonardo Aguilar Suarez, Gregory Beroza, William Ellsworth, Patricia Pedraza, Germán Prieto
Quantum Physics
Detuning-robust Rydberg entangling gates from echoed pulses
Zhubing Jia, Yichao Yu, Xiye Hu et al. (+4 more)
Rydberg-based two-
qubit gate fidelities in neutral atom arrays are limited chiefly by
laser intensity inhomogeneity and by detuning errors from frequency miscalibration, background-field drift, intermediate state light shift and Doppler shifts.
Quantum optimal control can suppress the former, but no pulse can render a controlled-Z gate first-order insensitive to detuning. Here we show that this obstruction can be circumvented by designing Rydberg gate pulses with every leading-order detuning error relegated to single-
qubit Z-rotations, which an echoed sequence removes. The resulting maximally-entangling ZZ gate has no leading-order response to arbitrary detunings on either atom, maintaining an infidelity below $10^{-3}$ within a much wider range of single-atom detunings than the time-optimal gates. We further show that a large fraction of residual error is dominated by population outside the computational subspace, which can be converted into heralded erasures. Our results significantly reduce the requirements on
laser frequency stability and intensity homogeneity, field calibration and atomic temperature toward practical fault-tolerant
quantum computing with neutral atoms.
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All authors Zhubing Jia, Yichao Yu, Xiye Hu, Lintao Li, Jacob Zheng, Christopher Monroe, Jacob P. Covey
Optics
Phase retrieval based on intensity-only spatiotemporal wavefront shaping
Luis Alberto Razo-López, Marc Guillon, Fabrice Lemoult et al. (+1 more)
We introduce a phase
retrieval method based on harmonic field representations generated by intensity-only spatiotemporal modulation. A periodic amplitude angular modulation encodes phase information into temporal intensity harmonics, enabling wavefront reconstruction without interferometry, reference beams, or a calibrated phase modulator. We consider a disordered system that can be modeled as a phase plate and measure the intensity pattern in the far field for a rotating excitation pattern generated by a digital micromirror device (DMD). We extract the harmonic components of the spatiotemporal speckle and exploit a gradient-based optimization
algorithm to retrieve both the optical phase in the plane of the camera corresponding to a plane-wave illumination and the effective phase plate that represents the disordered system. We demonstrate experimentally the accuracy of the approach in quantitatively estimating and compensating for phase distortion ranging from low-spatial-frequency aberrations to high-frequency distortions of a ground-glass diffuser. The proposed approach establishes a new route toward calibration-free phase
retrieval using intensity-only measurements.
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All authors Luis Alberto Razo-López, Marc Guillon, Fabrice Lemoult, Sébastien M. Popoff
High Energy Physics (Theory)
Scalar QED effective action in dS: implications for primordial magnetogenesis and the running of coupling constants
Ehsan Bavarsad, Sang Pyo Kim, Clément Stahl et al. (+1 more)
Particles creation and
vacuum polarization under the influence of both an electromagnetic field and a de~Sitter (dS) spacetime nonperturbatively probes
quantum electrodynamics (QED) and
quantum gravitational effects. By applying the gamma-function regularization to the in-out formulation, we find the exact one-loop effective action in the proper-time integral representation for a charged scalar field in a uniform electric field and a parallel
magnetic field in a dS spacetime. It reduces to the one-loop scalar QED Weisskopf-Schwinger effective action in the limit of Minkowski spacetime and the one-loop effective action in the pure dS spacetime. After carefully considering the different limiting cases, a striking result concerns the effective strengths of the coupling constants in the pure strong electric field limit. Our study provides further evidence for
evolution of Newton's gravitational constant under the influence of the external fields. Remarkably, the analysis of the effective potential shows that the leading order contributions to the
vacuum polarization amplitude, depending on the nonminimal coupling threshold, give a nonzero
vacuum expectation value of the
magnetic field. This mechanism generates a large
magnetic field in the early dS stage of the expansion that may imply
primordial magnetogenesis.
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All authors Ehsan Bavarsad, Sang Pyo Kim, Clément Stahl, She-Sheng Xue
Computational Physics
Automatic generation of exchange-correlation response kernels
Susi Lehtola
Computing density-functional response properties requires contracting derivatives of the exchange–correlation (xc) energy with perturbed densities on a grid. While the xc functional's derivatives have long been available to high orders from libraries such as Libxc, the surrounding contraction layer - the chain rule that combines them with the grid-based basis-function and density data into the total xc contribution - has instead been hand-derived and hand-coded in every program, for every functional family,
spin case, and property. We present libxckernel, a library that automatically generates this layer by symbolic differentiation. The xc functional's ingredients are expressed as sesquilinear forms in the density
matrix, so the xc energy can be differentiated to any order while the functional derivatives remain opaque. The basis functions and the orbital coefficients may both be complex. The chain rule then produces any xc
matrix element: Fock
matrices, orbital Hessians, and response terms of any order. Terms sharing a pattern are collapsed for efficiency. Extensible plugins emit the expressions as NumPy Einstein sums, compiled C kernels with C++/Fortran interfaces, or host-program specific source code. libxckernel is free and open-source software under the BSD-3-Clause license, enabling rapid implementation of functionality missing from many electronic structure programs. We demonstrate it by extending Psi4 with meta-generalized gradient approximation (mGGA) response kernels for orbital stability analysis and time-dependent density-functional theory (TD-DFT), GGA and mGGA analytic
nuclear Hessians, and exact quadrature grid response, and by extending GPAW with mGGA and triplet TD-DFT kernels and gradient-corrected kernels for periodic dielectric response.
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