Geophysics
Does High Signal-to-Noise Ratio Identify Better Training Data for Seismic Deep Learning?
Ziye Yu, Xin Liu and Yuqi Cai
Hard signal-to-noise ratio (SNR) screening removes weak seismic records, but does retaining clearer waveforms improve learning enough to compensate for the discarded data? We test this question in phase picking and ambient-noise dispersion, first matching training counts and then restoring the full eligible dispersion pool at fixed compute. Phase-picking screening gave no consistent unfiltered-test benefit under fine-tuning or random initialization, including a control matched on distance and phase composition. Dispersion screening increased error at the original five-epoch endpoint but improved on an equally sized unscreened set after longer training. Retaining all 29,788 eligible fit paths instead of 9,929 randomly sampled paths reduced unfiltered-test error by 3.0% across three seeds at the same update budget. Full-available and strict-SNR training then had similar mean errors, 0.0405 and 0.0406 km s$^{-1}$, with mixed seed-paired ordering; strict training retained a 9.9% advantage on the SNR-selected test. In two-day monitoring, SNR regulated pick streams but event recovery depended on its measurement definition. High SNR did not reliably identify better training data: gains depended on the task, training schedule, and test domain, and fixed-count comparisons omitted the benefit of retaining additional valid examples.
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Geophysics
Convergent representations of elastic-wave structure emerge across deliberately distinct seismic training routes
Ziye Yu, Yuqi Cai and Xin Liu
Elastic-wave propagation connects laboratory fracture with earthquakes, raising the prospect of seismic models that reuse waveform structure across physical scales. Here we show that the phase picker PNSN and the multi-task model SeismicXM organize unseen laboratory acoustic emissions around common waveform relations. Their representations agree on 512 held-out records relative to matched random networks. Four earthquake-model families also track displaced laboratory arrivals without fitting target neural weights. Receiver-function classification is accessible to frozen pretrained features, although standardized random features remain competitive. Noise correlations test the extension to continuous propagation outputs: a nonlinear SeismicXM ensemble improves on random
topology, while a period-wise median remains more accurate. Waveform interventions and synthetic controls reveal that the observed agreement depends on feature calibration and the waveforms being compared. These results establish convergent waveform organization across distinct seismic training routes and show that cross-scale arrival transfer is already accessible to compact models.
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Superconductivity
Enhanced Critical Currents and Irreversibility Fields in YBa$_2$Cu$_4$O$_8$ Films through Ca-Substitution
Jiangteng Liu, Shuhei Funaki, Yuki Ogimoto et al. (+6 more)
The intrinsic carrier concentration of superconducting materials may not be optimal, and different superconducting properties may have distinct optimal doping levels. Here, we show that Ca substitution increases the hole concentration in intrinsically underdoped epitaxial (Y$_{1-x}$Ca$_x$)Ba$_2$Cu$_4$O$_8$ (YCa124) films with $x \leq 0.10$, driving YCa124 toward optimal doping, increasing $T_c$ and $J_c$. At 40 K, 10% Ca doping increases $J_c$ by factors of 2.4 and 10 at 0.03 and 6 T, respectively, compared with the undoped film. The field dependence of $J_c$ follows $J_c \propto B^{-0.5}$, independent of Ca content, indicating that Ca substitution does not alter the dominant pinning mechanism. This field dependence is consistent with pinning by planar Y-125 stacking-fault intergrowths observed by electron microscopy. In addition, Ca substitution slows thermally activated
vortex motion (creep) at $T \gtrsim 15$ K, while at lower temperatures the creep rate $S$ shows an unusual decrease with increasing field. Finally, we consider how doping tunes the upper bound on $J_c$, set by the depairing current density $J_d$, and the lower bound on creep, set by the Ginzburg parameter $G_i$. We find positive correlations between $J_c$ and $J_d$, and between $S$ and $G_i$, and compare them with trends across a broad range of
superconductors.
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All authors Jiangteng Liu, Shuhei Funaki, Yuki Ogimoto, Bryan Zhang, Ryoya Nagaura, Ryuji Yoshida, Takeharu Kato, Masashi Miura, Serena Eley
Physics Education
From Two-Level Hamiltonians to Quantum Superposition and Measurement: A Traceable Classroom Module
Boris Kiefer
We present a traceable instructional module that maps documented learner difficulties in
quantum superposition and measurement to explicit learning goals, classroom activities, and assessment evidence. Using the general two-level
Hamiltonian as the organizing physics framework, the module implements this mapping through a five-activity classroom sequence and grading rubric targeting four recurrent difficulties: interpreting superposition as physical splitting, confusing a
quantum state with its representation or measurement context, mixing theoretical probabilities with finite-sample frequencies, and using inconsistent notation across states, amplitudes, probabilities, and measurement outcomes. The instructional design is organized through a reversible mapping from documented barriers to learning goals, activity responses, and assessment evidence, allowing each assessment item to be traced back to the specific difficulty it is intended to address. The module uses the standard general two-level Hermitian
Hamiltonian, represented by a \(2\times2\)
matrix, as the physical framework connecting its eigenstates, computational-basis amplitudes, Born probabilities, and sampled outcomes. The contribution is a challenge-targeted instructional design that organizes standard
quantum mechanics into a traceable classroom sequence linking documented learner difficulties to learning goals, activities, assessment criteria, and implementation guidance. The mathematical structure uses standard
Hamiltonian and measurement conventions, supporting direct incorporation into an undergraduate
quantum-mechanics course.
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High Energy Astrophysical Phenomena · Cross-listed from math.NA
An Energy-Conserving Unstaggered Electromagnetic-Potential Particle-in-Cell Method, Part II: Fully Relativistic Formulation with an Adapted Higuera–Cary Pusher
Andrew Christlieb, Luis Chacon and Sining Gong
We develop a fully relativistic extension of the energy-conserving, unstaggered electromagnetic-potential particle-in-
cell method introduced in our earlier nonrelativistic work. As in the nonrelativistic generalized-momentum formulation, the fields are advanced by a Crank–Nicolson discretization of the Lorenz-gauge potential equations, the current is deposited from particle orbits, and charge is advanced through the discrete continuity equation. The new ingredient is a generalized-momentum adaptation of the Higuera–Cary relativistic particle pusher. The vector-potential force is decomposed into an orbit-discrete-gradient part, which enforces the same finite-difference chain rule used in our earlier nonrelativistic formulation, and a skew part, which generates a Higuera–Cary
magnetic rotation in mechanical momentum. For prescribed fields and frozen orbit data, this generalized-momentum Higuera–Cary map is a unit-Jacobian conjugacy of the mechanical Higuera–Cary map and preserves particle phase volume in $(\xx,\PP)$. For the fully coupled implicit step, the same orbit data define the current deposit, mesh-to-particle gather, vector-potential chain rule, and relativistic kinetic-energy secant velocity. The resulting particle work cancels the Crank–Nicolson field-energy balance, yielding exact relativistic total-energy conservation up to nonlinear solver tolerance, orbit-quadrature error, and roundoff. A self-adjoint
Fourier projection removes modes on even-grid Nyquist planes while preserving the particle–grid work identity. Numerical tests are organized around cold relativistic two-stream and Weibel/filamentation instabilities, with diagnostics for energy drift, Gauss's law, the Lorenz gauge, particle–grid work, and the orbit chain rule.
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Solar and Stellar Astrophysics
Properties of Circumfacular Regions derived from H$\alpha$ and Ca II K synoptic observations of the Sun
Serena Criscuoli and Andrea Diercke
Circumfacular regions are dark chromospheric structures surrounding
magnetic regions whose properties and contribution to
solar activity diagnostics remain poorly understood. We investigate their photometric and
geometric properties using full-disk H$\alpha$ and Ca II K observations acquired by the Chromospheric
Telescope (ChroTel) from 2012 to 2020, spanning the maximum and declining phases of
solar cycle 24 and the beginning of cycle 25. We develop an automated
segmentation algorithm to identify circumfacular regions and define a photometric index analogous to existing excess and deficit indices. We compare their temporal
evolution with those of plages, dark features, and filaments on
solar-cycle and Carrington-rotation timescales. Circumfacular regions develop after the H$\alpha$ plage brightening become visible and persist into the decay phase of active regions. At activity maximum, they are the most extended chromospheric structures, covering more than half of the visible
solar disk. Their mean intensity varies only weakly throughout the
solar cycle; consequently, their index variability, as well as that of the other photometric indices, is driven primarily by changes in area coverage. H$\alpha$ and Ca II~K indices are strongly correlated, although their correlations weaken toward
solar minimum. This activity-dependent relationship is primarily driven by the decline of the area of H$\alpha$ excess regions during periods of low activity, and the increasing relative contributions of deficit and circumfacular regions. Our results therefore suggest that circumfacular regions should be considered when interpreting disk-integrated chromospheric observations of the Sun and
solar-type
stars.
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Atmospheric and Oceanic Physics
Suêtes: An end-to-end differentiable non-hydrostatic limited-area dynamical core
Tim Whittaker, Seth Taylor, Elsa Cardoso-Bihlo et al. (+2 more)
We present Suêtes, a fully differentiable, non-hydrostatic, limited-area atmospheric dynamical core implemented in JAX. Suêtes includes both a semi-implicit semi-Lagrangian scheme and a Split-Explicit Runge-Kutta scheme with acoustic substepping, enabling applications from coarse regional simulations to convection-permitting dynamics. Its terrain-following geometry, spatial discretization, time integration, initial conditions, lateral boundary treatment, and included physical parameterizations are all compatible with reverse-mode automatic differentiation. A single reverse-mode pass can therefore compute sensitivities of forecast diagnostics to selected initial and boundary fields, physical parameters, topography, and computational geometry. We provide a series of numerical experiments—including a tracer-source inverse problem, a sensitivity analysis of a three-dimensional squall-line,
adversarial perturbation construction an ERA5-driven downslope hurricane force wind event, topography optimization, and terrain-following coordinate optimization—demonstrating the versatility of Suêtes as a framework for gradient-based diagnosis and model development at regional and convection-permitting scale.
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All authors Tim Whittaker, Seth Taylor, Elsa Cardoso-Bihlo, Alejandro Di Luca, Alex Bihlo
High Energy Physics (Theory) · Cross-listed from math.QA
Meromorphic open-string vertex algebras and twisted modules from Courant algebroids
Qixuan Fang and Fei Qi
We construct a sheaf of $\frac{1}{2}\mathbb{Z}$-graded meromorphic open-string vertex
algebras from a transitive Courant algebroid $E$ equipped with a generalized metric and a chosen generalized Levi-Civita connection on a smooth
manifold. Using a holonomy principle for transitive anchored bundles, we realize these
algebras as parallel sections of a tensor
algebra bundle built from bosonic-fermionic affinizations of $E$. For even-rank $E$ with suitable Clifford module bundle data, we construct a sheaf of canonically twisted modules containing the canonical weighted spinor bundle in weight zero. The associative
algebra of parallel tensors acts on spinor sections through iterates of an $E$-connection combining covariant differentiation and Clifford multiplication, with mixed terms incorporating the action of the bosonic connection on fermionic tensors. Distinguished states built from the inverse Courant pairing and inverse generalized metric give vertex-operator components, acting on embedded spinor sections as the canonical Dirac generating operator, its formal adjoint, and their anticommutator, the generalized Hodge
Laplacian. In the exact Courant case with three-form $H$ and the exterior
algebra Clifford module, the operators specialize to $d-H\wedge$, its adjoint, and the twisted Hodge
Laplacian, reducing to the ordinary de Rham and Hodge operators when $H=0$. This extends the vertex-operator realization of
geometric differential operators from functions to weighted spinors and differential forms, within the program of studying two-dimensional supersymmetric nonlinear sigma models.
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High Energy Physics (Phenomenology)
$t\bar{t}$ spin correlations from toponium production scenarios to non-relativistic resummation beyond the standard perturbative baseline
A. Cota Rodríguez, Jesús A. V. Corral, A. Paredes Sotelo et al. (+1 more)
$t\bar{t}$
spin correlations originating from theoretical models assuming on one side toponium bound state formation in
proton-
proton collisions at 13 TeV are compared against predictions from non-relativistic QCD ressumation effects via Green's function formalism that go beyond the perturbative $t\bar{t}$ baseline with no bound state but could justify extra yield of events in the $t\bar{t}$ mass spectrum recently observed by ATLAS and CMS Collaborations, still awaiting an explanation. Toponium production comprises two scenarios, a simplified Effective Field Theory (EFT) with $\eta_t\rightarrow t\bar{t}$ decays and an additional model with scalar and vector toponium states with $\eta_t\rightarrow HZ$ and $J_t\rightarrow ZW^+W^-$ decays. Experimental measurements on $t\bar{t}$ system are added to the comparisons. Fitted diagonal
spin correlation $C_{kk}$, $C_{rr}$, $C_{nn}$
matrix terms show a relative increase in value ranging from 200%-2330% for toponium $t\bar{t}$ decays with respect the perturbative NLO baseline. Relative contribution from resummation effect ranges from 0.6% to 10.4% and its combination with perturbative baseline improves agreement with Data distributions, with $\chi^2/N_\mathrm{dof}$ value reduced by $\sim$4.5%-60.0% . Equivalent fitted cross-section for resummation effect $\sigma_{res}$, ranges from 7.3 to 9.1 pb in consistency with excess yield reported by LHC experiments. $\sigma_{res}$ $>$ 50 pb range is excluded at 95% C.L. A classifier performing at detector level achieves a ROC curve area of $0.91$ leading to toponium signal to background significances over 55. These results indicate that efficient isolation of observed $t\bar{t}$ excess events from background is feasible and a characterisation via
spin correlation measurements would reveal their consistency with either toponium production or non-relativistic effects beyond the perturbative baseline.
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All authors A. Cota Rodríguez, Jesús A. V. Corral, A. Paredes Sotelo, J. A. Murillo Quijada
Medical Physics
Cardiac segmentation for ventricular tachycardia radioablation and radiotherapy patients with cardiac implants
Nicholas Summerfield, Dustin Jacqmin, Chase Ruff et al. (+8 more)
Deep-learning (DL)
segmentation enables cardiac substructure (CS) delineation for advanced cardiac-sparing radiation therapy (RT). Patients presenting for RT may have implantable devices (cardioverter-defibrillators (ICDs)) and metal artifacts. Stereotactic body RT (SBRT) is used to treat ventricular tachycardia (VT), a population frequently with ICDs. We apply a DL model for RT patients with ICDs or undergoing VT-SBRT, enabling
segmentation and CS-level dose analysis. CT simulation (CT-SIM) of 19 patients with ICDs and received VT-SBRT were evaluated. A validated
segmentation model was retrained using a highly-curated CT-SIM cohort, supplemented with ICD images for training and validation, with a hold-out ICD test set (n=10), to predict 20 CS. Additional CT-SIM
datasets included cancer-RT patients with (n=9) and without (n=10) ICDs to evaluate generalizability. The retrained ICD-supplemented model was compared against a non-ICD model using Dice similarity coefficient (DSC), 95% Hausdorff distance (HD95), and Wilcoxon signed-rank test (p<0.05). Dosimetric evaluation was performed for VT-SBRT CS. For VT-SBRT, the ICD-supplemented model achieved average DSC/HD95 of 0.71(0.19)/10.7(22.5)mm respectively, outperforming (p<0.05) the non-ICD model. On CT-SIM with ICDs, average DSC/HD95 were 0.70(0.22)/7.9(5.1)mm respectively, outperforming (p<0.05) the non-ICD model. On CT-SIM without ICDs, the average DSC was 0.74(0.17) (Non-ICD, DSC, 0.75(0.16), p<0.05) and average HD95 was 5.5(3.1)mm (Non-ICD, HD95, 5.3(2.8mm)). For VT-SBRT, CS dose depended on target location, with higher relative dose delivered to the ventricles, tricuspid valve, atrioventricular node, and left coronary arteries than other CS. ICD-supplemented training improved CS
segmentation despite metal artifacts without meaningfully degrading non-ICD performance, supporting
segmentation and CS-level dosimetry in ICD populations.
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All authors Nicholas Summerfield, Dustin Jacqmin, Chase Ruff, Andrew M. Baschnagel, Adam Burr, Michael Bassetti, Ryan Kipp, Matthew Kalscheur, Patrick M. Hill, Ming Dong, Carri Glide-Hurst
High Energy Physics (Phenomenology)
Effective kinematic variables for searching for dark matter mediators in single top quark production processes
E.E. Boos, V.E. Bunichev and L.V. Dudko
Effective kinematic variables are proposed in the rest frame of the common cluster of the top
quark and mediator decay products for searching for and determining the type of dark matter mediator particles and measuring their masses in single top
quark production processes. The efficiency of the variables is confirmed by full Monte Carlo simulation taking into account the response of the LHC detectors.
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High Energy Physics (Phenomenology)
Vector Meson Dominance and Vector Meson Production
Craig D. Roberts
Against a background supported by the three pillars of emergent mass, this contribution challenges the fidelity of vector
meson dominance as an instrument for relating the electromagnetic vector-
meson (V) production reaction $e + p \to e^\prime + V + p$ to the hadronic process $V + p \to V + p$. It also describes a viable reaction model for exclusive photoproduction of light and heavy vector
mesons from the
proton, which exposes the $q\bar q$ content of the
photon. That model's successes reveal that it is premature to link extant $V + p \to V + p$ data with, for instance, in-
proton gluon distributions, the QCD trace anomaly, or pentaquark production. Improved reaction theory and more precise data are required before the validity of such links can objectively be assessed.
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Strongly Correlated Electrons
Artificial versus Natural Atoms: The uncanny capability of the many-body Schrödinger equation to produce emergent behavior
Constantine Yannouleas
The paper reviews the theoretical and experimental progress achieved in the last 25 years in understanding the novel physics of artificial atoms and molecules as arising from the formation of Wigner molecules (WMs) of localized (to a stronger or lesser extent) fermionic or bosonic particles, which are finite
quantum analogs of the more familiar bulk Wigner
crystal. The term artificial atoms, as used here, encompasses a broad range of recently fabricated
quantum nanodevices and experimental apparatuses consisting of a finite number of mutually repelling confined particles, including two-dimensional
semiconductor and moiré transition metal dichalcogenide
quantum dots, as well as trapped ultracold neutral atoms or ions. These nano-sized or micro-sized artificial devices and apparatuses (in single well or multi-well of variable-shape arrangements) hold a great promise for technological applications in the field of
quantum information and
quantum computers, as well as for advances in fundamental many-body physics. Prominent
quantum effects of Wigner molecularization are the strong quenching of the spectral energy gaps, the appearance of rovibational spectra (in analogy with natural molecules),
entanglement, and pinning due to an external perturbation. In high
magnetic fields or at rapid rotation, WMs provide an alternative theory to the fractional
quantum Hall effect. The physics of Wigner molecules is shown to derive from the solutions of the many-body Schrödinger equation (MBSE) in the regime of strong interparticle correlations arising from the dominance of the potential over the kinetic energy, or from a high
magnetic field, as well as from a rapid rotation... (continues in the paper).
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Cosmology and Nongalactic Astrophysics
Probing Baryons with the Kinematic Sunyae Zel'dovich Effect and Machine Learning Derived Peculiar Velocities using DESI DR2 and ACT DR6
Yulin Gong, Rachel Bean, Patricio A. Gallardo et al. (+54 more)
We present novel empirical constraints on average optical depths and gas density profiles from combining kinematic Sunyaev Zel'dovich effect (kSZ) measurements and nonlinear peculiar velocities, reconstructed using machine learning, for massive
halos traced by DESI DR2 luminous red
galaxies (LRG). The pairwise kSZ is measured using two ACT DR6
cosmic microwave background (CMB) temperature maps (ILC and 150 GHz maps) for seven luminosity-selected LRG samples. We find consistent results between the two maps and significant detections across the samples. We reconstruct LRG line-of-sight peculiar velocities in two
cosmic epochs, centered on $z=$ 0.55 and 0.8, using a simulation-trained
Transformer machine learning model to extend beyond the linear approximation. Average optical depths are inferred by comparing the kSZ pairwise correlation to the measured pairwise velocity correlation from the reconstructed velocity field and, separately, from a theoretical prediction using the best fit Planck cosmology, with the highest significance reaching SNR = 14.2 and 15.1 respectively. We also obtain velocity-weighted AP-filtered kSZ-stacked cluster density profiles, which show evidence of extended ionized gas around massive LRG groups and no strong
redshift evolution within current measurement uncertainties. These results demonstrate the power of combining spectroscopic
galaxy and CMB data, and employing machine learning methods, to probe diffuse
baryons and coherent large-scale velocity fields. They open up new avenues to leverage upcoming
galaxy survey data from Euclid, Roman and Rubin LSST, in tandem with multi-frequency CMB/sub-mm data from CCAT and Simons Observatory.
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All authors Yulin Gong, Rachel Bean, Patricio A. Gallardo, Boryana Hadzhiyska, Yun-Hsin Hsu, Jenna Moore, Eve M. Vavagiakis, Nicholas Battaglia, J. Aguilar, S. Ahlen, A. Aviles, F. Beutler, D. Bianchi, D. Brooks, A. Carnero Rosell, T. Claybaugh, A. de la Macorra, Arjun Dey, Biprateep Dey, P. Doel, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, G. Gutierrez, K. Honscheid, S. Juneau, T. Karim, R. Kehoe, D. Kirkby, A. Kremin, O. Lahav, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, S. Nadathur, J. A. Newman, H. E. Noriega, E. Paillas, N. Palanque-Delabrouille, W. J. Percival, F. Prada, I. Pérez-Ràfols, C. Ravoux, G. Rossi, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, M. Schubnell, H. Seo, J. Silber, M. Siudek, G. Tarlé, B. A. Weaver, R. Zhou
Strongly Correlated Electrons
Quantum metric induced nonlinear transport in the hidden loop-current phase of kagome metal RbV$_3$Sb$_5$
Jia-Chen Shi, Shupeng Xu, Utkarsh Khandelwal et al. (+4 more)
A hidden low-temperature phase with possible loop-current order has been proposed in the kagome metals AV$_3$Sb$_5$ (A=K, Rb or Cs), but its experimental signatures remain subtle and indirect. Here, we use third-order nonlinear transport to probe this hidden phase in RbV$_3$Sb$_5$. At ~35 K, the longitudinal cubic response develops a strong kink and pronounced directional anisotropy with a strong departure from common relaxation time scaling, while the transverse cubic response acquires a
magnetic field-odd component at the same temperature. Their coincident onset identifies the third-harmonic response as a sensitive marker of the low-temperature electronic reconstruction with time-reversal broken
symmetry. Crucially, we find that the
quantum metric quadrupole contributes directly to the longitudinal third-order response. In a loop-current charge-density-wave model, its direction selective enhancement captures the observed angular reconstruction. Our work shows how higher-order nonlinear transport translates subtle changes in electronic
symmetry and
quantum metric into measurable electrical signatures in
quantum materials that is important for studying complex electronic phases of matter.
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All authors Jia-Chen Shi, Shupeng Xu, Utkarsh Khandelwal, Nashra Pistawala, Luminita Harnagea, Steven J. May, Ritesh Agarwal
Optics
Asymmetric imaging: Reciprocity bounds and manifestations
Romil Audhkhasi, Anna Wirth-Singh, Rose Johnson et al. (+6 more)
Recent demonstrations of unidirectional imaging using diffractive multilayers have brought a concept akin to optical isolation to imaging, yet the fundamental limits of such asymmetry have remained unknown. Here we develop a general theory of asymmetric imaging in linear, passive, reciprocal optical systems and derive a fundamental bound on the achievable unidirectionality. Reciprocity requires the forward and reverse transmission operators to have identical singular values, a wave-optical analogue of étendue equality, with a simple consequence: perfect asymmetry is attainable only for sets of $M \leq N/2$ orthogonal object patterns, where $N$ is the number of available object/image modes; for $M > N/2$, the average power asymmetry is bounded by $(N-M)/M$. Guided by this result, we present two complementary realizations: refractive imaging systems formed by bulk lenses and stops that attain the half-occupation limit, and a 1 cm-diameter all-silicon metasurface doublet that exhibits asymmetric focusing at 4 $\mu$m while fully complying with Lorentz reciprocity. We fabricate the doublet by direct
laser writing and experimentally demonstrate its focusing asymmetry. By establishing mechanism-independent limits, our results provide a
benchmark and design principle for asymmetric imaging across platforms, with implications for defense, surveillance and secure communications.
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All authors Romil Audhkhasi, Anna Wirth-Singh, Rose Johnson, Maksym Zhelyeznyakov, Vladimir Yarmolik, Rafael Piestun, Andrea Alù, Arka Majumdar, Owen Miller
Chaotic Dynamics · Cross-listed from cs.NE
Massively Parallel Reinforcement Learning with a Chaotic Reconfigurable Clockless Chip
Eric Oliveira-Gomes and Damien Rontani
Hardware accelerators based on physical dynamical systems offer an attractive route toward energy-efficient reinforcement learning applications. However, their scalability is challenging because it requires many statistically independent
entropy sources. Here, we introduce a quasi-analog decision-making architecture based on asynchronous Boolean networks (or
lattices) implemented on a clockless reconfigurable chip. Each node in the network consists of a single logic element that acts as an autonomous
entropy source. This architecture gives rise to distributed Boolean chaos, in which a spatially coupled network generates parallel streams of chaotic Boolean transitions with very low statistical dependence between nodes. We experimentally demonstrate parallel decision-making on a 1024-armed bandit problem, which is beyond the scale of previous hardware implementations, while significantly improving power-law scaling performance. Separately, we scale the proposed
entropy source to 5120 parallel channels, yielding an aggregate sample generation rate of 2.14 TS/s. Our solution is implemented on a commercial reconfigurable CMOS chip and offers high integration density and ease of programmability. Our results pave the way for using distributed Boolean chaos as a valuable hardware substrate for large-scale reinforcement learning and for the development of fully integrated, high-throughput decision-making accelerators.
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Geophysics
From Wildfire Severity to Snow Persistence: A Multisource GeoAI Study of the 2020 Creek Fire
Parastoo Farajpoor and Mohammadreza Narimani
Accurate prediction of post-fire snow conditions does not necessarily establish how wildfire changed those conditions. We developed an explainable geospatial artificial intelligence framework combining multisource Earth observations, meteorological information, and matched before-after comparisons to examine seasonal snow persistence following the 2020 Creek Fire in California's Sierra Nevada. Harmonized Landsat Sentinel-2 observations were used to estimate the fraction of clear-sky observations containing snow during October-July for eleven water years, 2016-2026, on a 500 m analysis grid. We matched 3,778 snow-zone
cells inside the fire perimeter to comparable unburned controls using terrain and pre-fire snow conditions; absolute standardized mean differences after matching were no greater than 0.047. HLS persistence agreed closely with MODIS, with a mean annual spatial correlation of 0.947. The landscape-average before-after control-impact contrast was +0.0017, with a year-level 95% confidence interval of -0.023 to +0.027. A stronger response emerged in the highest burn-severity class, where observed persistence increased by 0.026 relative to matched controls, equivalent to 2.6 percentage points. Under 5 km spatial cross-validation, XGBoost predicted raw post-fire persistence with an out-of-fold coefficient of determination of 0.811, whereas predictive skill for the fire-adjusted anomaly reached 0.046. Elevation and temperature together accounted for 65.7% of mean absolute model attribution. These findings distinguish a severity-associated optical snow response from the terrain-
climate relationships that dominate predictive skill. Combining matched comparisons with explainable GeoAI provides a practical framework for forest monitoring that separates accurate environmental mapping from inference about disturbance effects.
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Materials Science
Directional strain control of magnetism in MnBi$_2$Se$_4$, MnSb$_2$Se$_4$, and MnSb$_2$Te$_4$ freestanding monolayers
Swarnava Ghosh, Tanvir Sohail and Markus Eisenbach
MnBi$_2$Se$_4$, MnSb$_2$Se$_4$, and MnSb$_2$Te$4$ are layered
magnetic quantum materials of interest for spintronic and topological electronic applications, where control of
magnetic order at the atomic scale is essential. These materials are particularly sensitive to strain. We investigate their strain-dependent magnetism in the monolayer limit using first-principles calculations across the full two-dimensional strain space spanned by independent variations of the two in-plane strain components. Our results show that the Mn-projected local moments depend primarily on the volumetric strain, whereas the
magnetic ground state, exchange interactions, magnetocrystalline anisotropy, and ordering temperature show pronounced directional and composition-dependent responses. We also observe strain-induced competition between the phases, with MnBi$_2$Se$_4$, and MnSb$_2$Se$_4$ monolayers exhibiting a more diverse range of competing
magnetic states, while MnSb$_2$Te$_4$ monolayer remains
ferromagnetic over a larger portion of strain space. MnSb$_2$Te$_4$ also exhibits a substantially larger out-of-plane magnetocrystalline anisotropy, while showing a weaker dependence on strain than the Se-based materials. The calculated
magnetic ordering temperature maps further highlight the role of two-dimensional strain to tune thermal
magnetic stability in these materials. These results establish magnetoelastic trends across this family of Mn-based chalcogenide monolayers.
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Instrumentation and Detectors
A portable neutron scatter camera with isotropic sensitivity
S. G. Yoon, L. Larizgoitia, C. M. Lewis et al. (+2 more)
We describe the design and characterization of a
neutron scatter camera specifically developed for the study of
neutron fields (flux, energy, direction) in experimental areas of spallation facilities, where multiple
neutron sources can simultaneously contribute. A combination of hardware and logic triggers provides the isotropic response required for this application.
Neutron source locations are accurately reconstructed on images from a built-in 360$^\circ$ panoramic camera. The full understanding of
neutron fields that the device provides can be used for site selection and abatement of
neutron backgrounds affecting sensitive instruments such as coherent elastic
neutrino-
nucleus scattering (CE$\nu$NS) detectors to be located at the upcoming European Spallation Source.
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All authors S. G. Yoon, L. Larizgoitia, C. M. Lewis, F. Monrabal, J. I. Collar
Mathematical Physics · Cross-listed from math.SP
A sandwich theorem for the spectrum of graph coverings
Charles Bordenave, Wenbo Li and Joe Thomas
We show that all normal covers of a fixed finite graph $G$ sitting between the universal and maximal abelian covers share the same atomic part of their spectral measures. We give an explicit double formula for the mass of atoms which generalises and unifies known results on universal covering trees and maximal abelian covers. It also proves an extension of a
conjecture in physics literature on
hyperbolic lattices. Moreover, we also establish the logarithmic Hölder regularity of the continuous part of the spectral measures. Our proof combines techniques from von Neumann
algebras, matching theory and the monotone labelling method. In an appendix, we prove a converse generalised Gallai-Edmonds structural
theorem which might be of independent interest.
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Medical Physics
Bridging cone-beam CT and MRI to stopping power ratio maps: a modality-agnostic Brownian bridge approach to support robust adaptive proton therapy
Yuhao Yan, Qisheng He, Minglei Kang et al. (+4 more)
Purpose: Adaptive
proton therapy (APT) relies on routine offline CT simulations for updated anatomy. We present a modality-agnostic regularized Brownian bridge (rBBrg) framework to deterministically predict stopping power ratio (SPR) maps from CBCTs or MRIs. Methods: rBBrg consisted of (1) generation mapping where a Brownian bridge predicted SPR from input and (2) reconstruction mapping where a cGAN reconstructed input from predicted SPR. Class
embedding was adopted for modality conditioning. Efficient, deterministic prediction was achieved via one-step sampling. Unimodality rBBrg and ResNet were implemented for comparison. Matched-pair planning CT-CBCT (n=37) and CT-MRI (n=21) from head-and-neck cancer patients were evaluated. A calibration phantom was scanned to establish Hounsfield look-up table for real SPR. Predicted SPR maps were evaluated via mean absolute error (MAE), peak-signal-to-noise ratio and structural similarity against ground truth with demonstration of dosimetric performance. Results: For CBCT-SPR synthesis, most metrics were comparable across models (p>=0.05). Modality-agnostic rBBrg outperformed ResNet in MAEbone (0.059 vs 0.067, difference=11%, p<0.05) and showed lower MAEexternal than ResNet (0.038 vs 0.040, p=0.05). Modality-agnostic and unimodality rBBrg were comparable (p>0.05). Qualitatively, both rBBrg better preserved anatomical fidelity than ResNet. For MRI-SPR synthesis, performance was overall comparable across models (p>0.05). Modality-agnostic rBBrg obtained MAEexternal=0.057. Dose calculation comparisons between real and CBCT-predicted SPR were higher in modality-agnostic rBBrg predictions compared to ResNet with gamma pass rate=98.8%/99.3% vs 94.5%/96.9% at 2 mm/2%, respectively. Conclusion: A novel modality-agnostic rBBrg model was developed to generate high fidelity, deterministic SPR from CBCT or MRI to support efficient and flexible APT workflow.
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All authors Yuhao Yan, Qisheng He, Minglei Kang, Behzad Hejrati, Christian Hyde, Ming Dong, Carri Glide-Hurst
Quantum Physics
Separability rigidity of Gaussian states under positive domination
Evgeny Shchukin and Peter van Loock
We prove a separability
rigidity theorem for finite-mode Gaussian states. Let $\rho_G$ be Gaussian and let $\mathcal I$ be a fixed partition of the modes. If $\rho_G$ dominates a nonzero positive operator $T$ that is separable across $\mathcal I$, $0\neq T\preccurlyeq \rho_G$, then $\rho_G$ itself is separable across $\mathcal I$. The dominated operator is arbitrary and need not be Gaussian. The
theorem has three applications. First, any Gaussian channel admitting a nonzero
entanglement-breaking completely positive subchannel is itself
entanglement breaking, even when that subchannel is non-Gaussian. Second, if a resource state dominates a positive multiple of a faithful separable state, no finite-copy, postselected separability-preserving protocol can prepare an entangled Gaussian state exactly with nonzero success probability. Third, a connected graph of entangled Gaussian two-mode marginals certifies genuine multipartite
entanglement of every compatible global state, even if the global state is non-Gaussian; the certification is robust to sufficiently small trace-norm errors in the marginals. As a structural corollary, mixing states separable across different partitions cannot produce new Gaussian states, so full inseparability and genuine multipartite
entanglement coincide for finite-mode Gaussian states and identical copies of a biseparable Gaussian state cannot activate genuine multipartite
entanglement.
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Quantum Physics
Conversable Quantum Fire in the Standard Model
Ofer Casper, Barak Nehoran and Or Sattath
Quantum fire consists of
quantum states that can be efficiently functionally cloned but cannot be transmitted using one-way classical communication. Whereas all previous
quantum-fire constructions with proven untelegraphability are relative to an oracle, ours, based on one-shot signatures, is in the standard model. Our construction achieves two further notions that we introduce: (a) keyless untelegraphability, a strengthening of untelegraphability; and (b) conversability, meaning that a flame, though not telegraphable via one-way classical communication, can be transmitted via classical interaction. Hence one-way and two-way classical communication differ qualitatively in their power to transmit this
quantum fire. We use these two novel properties of
quantum fire, along with its clonability, to give one of the first cryptographic applications of
quantum fire. Keyless untelegraphability forces the distribution of serial numbers of valid flames to have high min-
entropy, while conversability and clonability allow the corresponding flame to be cloned and transferred using only classical communication. We present two variants of our conversable
quantum-fire construction. The first, based on one-shot signatures (instantiable from subexponential iO, subexponentially secure one-way functions, and LWE), supports polynomially many flames, and super-logarithmic min-
entropy of the serial-number distribution. The second, under the stronger assumption of exponentially unforgeable one-shot signatures (instantiable relative to a classical oracle), supports exponentially many flames, and linear min-
entropy.
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Mathematical Physics
Combinatorics and loop equations for antisymmetrised and Hermitised matrix product ensembles
Stephane Dartois and Anas. A Rahman
The order $m$ antisymmetrised
matrix product ensemble is represented by the product $X_1^T\cdots X_m^TJX_m\cdots X_1$, where $X_1,\ldots,X_m$ are independent real Ginibre
matrices and $J$ is the elementary antisymmetric
matrix, while the order $m$ Hermitised
matrix product ensemble is represented by $X_1^\dagger\cdots X_m^\dagger HX_1\cdots X_m$, where $X_1,\ldots,X_m$ are now independent complex Ginibre
matrices and $H$ is a Hermitian
matrix drawn from the Gaussian
unitary ensemble. These ensembles have recently been shown to be related to certain Muttalib–Borodin ensembles and integrals of Harish-Chandra–Itzykson–Zuber type, thereby motivating further investigation into their
eigenvalue statistics. In this work, we construct ribbon graphs and constellations that are enumerated by the mixed cumulants of these ensembles and give loop equation characterisations for the generating functions of said cumulants when $m=1$.
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General Relativity and Quantum Cosmology
Computing gravitational radiation from highly eccentric bound binaries in the small-mass-ratio limit
Diego Andrés Rivera Orona and Scott A. Hughes
Precise strong-
gravity models describing the
evolution of bound compact binary systems provide important information about the gravitational radiation such binaries generate and how they evolve due to the radiation's backreaction. The limit of very high eccentricity, $e \to 1$, is challenging to model: frequency-domain techniques require many harmonics to accurately describe radiation in this limit, and time-domain techniques can be slow to converge due to the systems' long timescales. Many recent astrophysical analyses have nonetheless emphasized the importance of understanding gravitational-wave emission in this regime, highlighting the fact that many systems may evolve through $e \simeq 1$ en route to becoming detectable sources, and may enter the sensitive band of detectors with substantial eccentricity. In this paper, we show how to adapt frequency-domain methods for computing gravitational radiation in the small-mass-ratio limit to effectively handle high eccentricity. The key piece of this analysis is an integral over the source of the frequency-domain Teukolsky equation. We examine features of this integral that make it difficult to evaluate as $e \to 1$, and study methods to circumvent these difficulties. We find a simple fix which allows us to compute gravitational-wave amplitudes and the associated fluxes of energy and angular momentum with ease up to eccentricities $e = 0.99$; with patience (and stamina), we have pushed to $e = 0.999$, though numerical accuracy appears to degrade for such extreme cases. Interestingly, we find that the well-known and often used classic formulas of Peters and Mathews are subject to a systematic error which persists at quite wide separation. This has implications for models of compact binary formation which evolve through $e \simeq 1$.
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Classical Physics
Parametric excitation of rotational soft modes of the buckled discrete elastic ring
Panagiotis Koutsogiannakis and Massimo Ruzzene
In the present study, we explore the existence and characteristics of a rotating vibrational mode in a discrete buckled ring that manifests under transverse harmonic forcing. The study is conducted through mathematical analysis complemented by numerical simulations. The ring is composed of uniformly distributed concentrated masses connected by linear and torsional springs and supported by an elastic foundation. The buckled state of interest results from homogeneous in-plane compression and is characterized by vibrational modes that have a rotating nature because of the rotational
symmetry of the system. The resulting vibrational mode, called a rotational soft mode, is characterized by large amplitude rotations of the ring deformation while keeping its angular momentum zero. It is shown that rotational soft modes can be activated via transverse harmonic forcing through parametric resonance, which is possible only when nonlinearities are introduced to the foundation. In the absence of nonlinear behavior, transverse vibrations of the ring cannot lead to excitation of the rotational mode. Analysis of a constrained kinematics model shows that linear stiffness of the foundation leads to decoupling of the rotational mode from transverse vibrations. When the foundation is considered piecewise linear, with different stiffness values in compression and in extension, it is shown that three different behaviors are possible for the dynamic response of the forced ring: i) no rotation, ii) a limit cycle within a limited finite rotation angle range, iii) induced rotation between subsequent
equilibrium angles. The present study contributes to the understanding of the activation and control of soft modes in buckled structures and may lead to actuation applications in soft robotics, as well as advanced manipulation strategies of molecular systems in the context of nanomechanics.
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High Energy Astrophysical Phenomena
JWST/MIRI Spectroscopy of the Quiescent Black Hole X-ray Binary XTE J1118+480: Constraints on Jet and Circumbinary Dust Contributions to the Mid-infrared Emission
Zihao Zuo, Elena Gallo, Nuria Calvet et al. (+9 more)
We report on JWST/MIRI low-resolution spectroscopy ($5$-$12 \mu$m) and imaging ($15$-$25 \mu$m) of the black hole X-ray binary XTE~J1118+480 in quiescence, at an X-ray luminosity nine orders of magnitude sub-Eddington, together with contemporaneous optical monitoring and a
radio upper limit of $4.5~\mu$Jy at 6 GHz. With the donor subtracted, the $5$-$12 \mu$m continuum is curved, turning over near $6~\mu$m; a single power law is rejected in favor of a $764\pm 9$ K blackbody. Longward of the turnover the spectral index is $\alpha = +1.21\pm0.36$, steeper at the $2\sigma$ level than the flat to slightly inverted spectrum of a compact jet. Interpreted as synchrotron, the turnover implies equipartition fields of $\sim$$10^{4}$ G on scales of tens of gravitational radii, but the MIRI photometry at $15$-$21~\mu$m-taken $2.6$ hr before the spectrum-lies $30$-$90$ per cent above its extrapolation, suggesting a second self-absorbed zone. A single partially self-absorbed jet spectrum can reach the photometry only at the expense of the spectral
curvature and the $25.5~\mu$m upper limit, so a steady compact jet is disfavored, although not excluded. Representative self-consistent irradiated-disk models instead reproduce the principal features of the $5$-$25~\mu$m spectral energy distribution, with a directly illuminated
dust wall at $\simeq 5$ binary separations, outside the
tidal-truncation radius, and a minimum
dust mass of order $10^{22}$ g. This is the first spectroscopic evidence, though not yet conclusive, favoring circumbinary
dust over a jet in a quiescent black hole X-ray binary.
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All authors Zihao Zuo, Elena Gallo, Nuria Calvet, Richard M. Plotkin, David M. Russell, Gabriele Cugno, Rob Fender, Fraser Lewis, Joseph Michail, Jon M. Miller, James C. A. Miller-Jones, Fan Zou
Soft Condensed Matter
Multistability by Design in Complex Triangular Mechanical Metamaterials
Chaviva Sirote-Katz and Yair Shokef
We introduce frustrated triangular networks that mix two different beam thicknesses. The two thicknesses separate the energetic costs of second-order buckling and angular deformation into four competing contributions. Using scaling arguments and mapping to an effective Ising description, we construct the system's phase diagram in terms of its dimensionless
geometric parameters. Selected beam arrangements exhibit local bistability: hexagonal motifs switch independently between opposite twisting states, while linear motifs support independently switchable beam states. In both cases, the number of mechanically stable configurations grows exponentially with system size. Experiments on fabricated silicone metamaterials confirm the predicted bistability and local switching. More generally, the allowed beam arrangements map onto rhombus tilings, producing a large combinatorial space of architectures. The system thus combines multiplicity in both architecture and stable deformation states, establishing beam-thickness patterning as a route for programming frustration, multistability, and extensive degeneracy in triangular mechanical metamaterials.
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Plasma Physics
Resonant and Ponderomotive Pumping of Zonal Flows by Turbulence, Alfvén Eigenmodes, and Radiofrequency Waves
C. M. Gallaro and I. Y. Dodin
Analytical studies of zonal-flow (ZF) excitation by fluctuating fields, such as drift-wave
turbulence and Alfvén eigenmodes (AEs) driven by energetic particles (EPs) in tokamaks, are usually carried out via intricate gyrokinetic calculations and simulations whose results are notoriously difficult to interpret. Here, we report a transparent result that is also not limited to any particular modes or frequency range. Using oscillation-center theory that captures both ponderomotive forces and quasilinear
diffusion, we derive a compact formula for the ZF drive produced by any fluctuating field in terms of the field's canonical momentum and the dissipation power density. For ZFs generated by drift waves, our model subsumes the local relation between the zonal velocity and the drift-wave energy density that was previously derived ad hoc. The simplicity and generality of our result also opens a path toward optimization of ZF excitation with external waves and bridges the physics of AE-EP interactions with that of poloidal flows driven by radiofrequency waves in fusion
plasmas.
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