Mathematical Physics
Level lines of the Gaussian free field and $c=1$ degenerate conformal blocks
Alex Karrila, Eveliina Peltola and Lukas Schoug
We consider Gaussian free field (GFF) on simply connected domains with piecewise constant Dirichlet boundary data. We show that the crossing probabilities for its level lines are determined by conformal blocks of primary fields in a conformal field theory (CFT) with central charge $c = 1$ which are degenerate at each insertion. Alternatively, the crossing probabilities are ratios of explicit partition functions of fused multiple $\mathrm{SLE}_4$ curves, which can be written in terms of fused Specht
polynomials introduced recently by Lafay, Peltola, & Roussillon in a representation-theoretic context. We also prove that for the metric graph GFF introduced by Lupu, with appropriate boundary conditions, the crossing probabilities for its level sets converge in the scaling limit to our formulas. In particular, the geometry of the level-set percolation for both the continuum GFF and the metric graph GFF has a CFT description in terms of the aforementioned $c=1$ conformal blocks, which are linearly independent and solve the Belavin-Polyakov-Zamolodchikov (BPZ) PDEs of arbitrary orders. Interestingly, not all combinatorial boundary conditions are amenable for the GFF models – while the CFT contains conformal blocks of primary fields labeled by generalized Dyck paths (i.e., semi-standard Young tableaux), the ones appearing in the above models satisfy specific monotonicity constraints.
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High Energy Astrophysical Phenomena
Crust glass formation reveals the neutron star birth properties in IGR J17480-2446
D. A. Baiko and A. I. Chugunov
IGR J17480-2446 is a low-mass X-ray binary, harboring an exceptional accreting
pulsar (a
neutron star) with an unusual
spin frequency of 11 Hz and a very slow post-outburst crust cooling. The former may imply that it is observed at an early stage of recycling, while the latter was shown to indicate the presence in the outer crust of a low thermal conductivity layer, possibly made of glass. Here we argue that the glass layer formation is a natural result of
accretion induced failure of pristine cold
crystal crust. This allows us to determine the mass of the accreted material as $\Delta M \approx 2.4\times 10^{-6}~M_\odot$, confirming very early
accretion stage for this
neutron star. An analysis of
spin and thermal state reveals a peculiar set of
neutron star birth properties which is commonly associated with `recycled'
neutron stars, i.e.\ those that have been experiencing prolonged periods of
accretion from a companion. We speculate that such birth properties may represent the outcome of
neutron star formation in an electron-capture
supernova.
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Lattice Field Theory
Proton's isovector PDF with updated analysis of large-momentum lattice data
Xiangdong Ji and Yushan Su
The
proton's unpolarized $u(x)-d(x)$ parton distribution function (PDF) has been studied by a number of
lattice QCD groups through large momentum expansion. However, due to
lattice artifacts (excited state contaminations, unphysical pion masses, and discretization effects) and less-advanced theoretical analysis (renormalizations, large-distance extrapolations, and large-log resummations), the resulting PDFs cannot be compared strictly with experimental data. By using the state-of-the-art theoretical tools and mitigating the
lattice artifacts empirically, we reanalyze the available
datasets in the literature and find that the new PDF for the physical-limit-extrapolated
dataset (MSULat20) is consistent with global fits within $\sim1\sigma$, while others are broadly compatible. This provides evidence that large momentum expansion is capable of accurately predicting the $x$-dependence of the PDFs when ideal
lattice data become available.
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Materials Science
A correlation of structural changes with nanomechanical properties in TiN-AlN multilayer films
Nidhin George Mathews, Aidan A. Taylor, Johannes Zechner et al. (+5 more)
The present work investigates the changes in overall nanomechanical properties of reactively sputtered TiN-AlN multilayer films arising due to phase transformation in the AlN layers. Multilayered TiN-AlN films were sputter deposited with constant TiN layer thickness of 5 nm while the AlN layer thickness varied between 1-5 nm. The AlN underwent a phase transition from cubic rock salt to hexagonal wurtzite above 3 nm thickness due to the
lattice strains. The hardness and indentation modulus of the multilayers decreased with increasing AlN film thickness, up to 3 nm, due to increased volume fraction of softer AlN layer and then stabilized for 4 nm and 5 nm thickness films. Micropillar compression of these multilayers showed a transition from columnar brittle to partially ductile failure associated with crack deflection with increasing AlN film thickness. Interestingly, nanoindentation scratch resistance of 3 nm AlN multilayer was observed to be superior compared to all other films. The crack propagation behavior in scratching showed increased microcracking tendency towards higher AlN film thickness. This shows that cubic to hexagonal transformation in AlN is beneficial for improving the damage tolerance of the multilayer system.
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All authors Nidhin George Mathews, Aidan A. Taylor, Johannes Zechner, Helmut Riedl, Paul H. Mayrhofer, Johann Michler, Vipin Chawla, Gaurav Mohanty
Physics and Society
Lost in Aggregation: A Multi-Scale Diagnostic Benchmark for LLM Spatial Navigation
Yuhan jiang, Peng Luo and Liqiu Meng
Large
language models (LLMs) are increasingly deployed as planners and assistants in tasks with inherent spatial structure, such as
navigation and route planning, yet they remain brittle in sequential spatial
reasoning. We ask not merely whether LLMs fail at
navigation but where in the spatial-cognition pipeline they get lost. We introduce a multi-scale diagnostic
benchmark that decomposes maze
navigation into three cognitive levels drawn from human spatial cognition: Fine (local passability), Meso (junction
topology), and Macro (global goal direction). We evaluate three instruction-tuned chat LLMs (GPT-4o, DeepSeek-V3, Llama-3.3-70B) on 1,050
topology-annotated mazes spanning seven sizes (3x3 to 30x30) and three difficulty tiers. The
benchmark is organized as three modules. (i) Input acquisition: among four input formats, structured coordinate text is the most navigable, far surpassing rendered images. (ii) Multi-scale representation: end-to-end one-shot
navigation collapses to near zero by 10x10 for every model, yet the same models respond to isolated single-level probes (Fine, Meso, Macro) at 30-75% far beyond that size. A multi-hot first-error analysis localizes failures to Meso junction choices (59%) and Fine perception (39%), with global direction almost never at fault (1%). The barrier is therefore the cross-scale aggregation of individually available competences over a long sequential plan, not any single perceptual deficit. (iii) Hierarchical route planning: delegating per-step execution to a deterministic walker and querying the LLM only at junctions, with an explicit
cell-type
prompt, lifts GPT-4o success by up to 92 points at mid sizes, but the same scaling wall re-emerges by 30x30. We release the
benchmark, mazes, and code as a reusable diagnostic instrument for spatial
reasoning in LLMs, available at https://yuhanjiang415.github.io/lost-in-aggregation/.
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High Energy Physics (Experiment)
Accelerating Discovery: Model-Agnostic Likelihoods for the Reinterpretation of Particle Physics Results and their Application to the Belle II $B^{+}\to K^{+}\nu\bar{\nu}$ Measurement
Lorenz Gärtner
Experimental results in high-energy physics are inherently hypothesis-dependent, as
collider analyses are designed to test specific theoretical frameworks. The proliferation of theoretical models creates a mismatch between the pace of theory development and experimental validation, motivating the reinterpretation of existing results in terms of alternative hypotheses. Existing strategies face limitations: full reanalysis requires enormous computational resources and experimental expertise, while simplified methods sacrifice accuracy by neglecting kinematic variations and systematic uncertainties. This thesis develops, validates, and applies a novel reinterpretation method that preserves statistical rigour while dramatically reducing computational requirements, enabling rapid inference on alternative theoretical parameters through distributable likelihoods. The method reweights the joint distribution of reconstruction and kinematic variables according to the ratio of theoretical predictions of alternative to null hypotheses. Starting from a histogram-based likelihood, this produces updated templates for any theoretical model while preserving correlations and systematic uncertainties. The method is validated through examples and applied to the Belle II $B^+ \to K^+ \nu\bar{\nu}$ measurement ($2.7\sigma$ tension with the Standard Model). Two analyses are presented: a Weak Effective Theory reinterpretation constraining Wilson coefficients, and a light new physics search via ${B^+ \to K^+ X}$ two-body decays. The public release of the resulting model-agnostic likelihoods establishes an important precedent for open science in experimental particle physics. By facilitating rapid theoretical validation, this approach democratizes experimental data access, enhances scientific return on investments, and advances FAIR Data principles in high-energy physics.
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Quantum Physics
Probing the Weak-Driving Quantum Speed Limit via Drift-Aware Shooting Methods
Denis Janković, Saba Taherpour, Paul-Louis Etienney et al. (+2 more)
A central goal of
quantum optimal control is to achieve high-fidelity and low-energy control pulses. When
quantum optimal control methods optimize every point of a pulse discretized over small time steps independently this can yield high fidelity control but also results in broadband and energy-hungry waveforms. We extend MAGICARP, a shooting method inspired by Pontryagin's maximum principle on energy that generates an entire pulse from a small set of parameters, making it smooth and energy-efficient by construction, from driftless systems to closed systems with the constant drift
Hamiltonian of two exchange-coupled
spins in an external
magnetic field. The optimization proceeds in stages: the dressed states of the drift
Hamiltonian structure the target, an initial shooting optimization is performed in the rotating-wave frame, and an exact laboratory-frame refinement follows. Benchmarked against Krotov and GRAPE at matched gate infidelity, MAGICARP consistently achieves the lowest energy and a conserved pulse area, concentrates its spectral weight on the gate-relevant transitions, and is the most robust to fluctuations in the exchange coupling; GRAPE independently converges to essentially the same pulse while black-box Krotov meets the same error at an order-of-magnitude energy premium. This method-independence is what qualifies the bounded solver as a measurement instrument, and the central result follows: a large statistical survey of unselected optimization runs resolves a weak-driving
quantum speed limit for two exchange-coupled electron
spins: low-amplitude realizations of the two-
qubit quantum Fourier transform cease to exist below a critical gate time, and the minimum control energy diverges on approach to this limit. The divergence obeys a simple two-parameter area–pole law, $E_2^{\mathrm{law}}(T)=A/T+B/(T-T^*)$.
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All authors Denis Janković, Saba Taherpour, Paul-Louis Etienney, Paul-Antoine Hervieux, Christoph Wolf
Statistical Mechanics
Giant Fluctuations in Self-Propelled Particles with Age-Dependent Switching
Shabnam Sohrabi and Farhad H. Jafarpour
We investigate the transport and fluctuation properties of self-propelled particles whose motion is governed by an age-dependent phase-switching mechanism. The dynamics alternate between a Markovian downstream phase with a constant switching probability $r$ and a semi-Markovian upstream phase in which the age-dependent hazard probability $a/(b+c)$ decays with the internal clock $c$, representing persistent orientation. The time-averaged velocity, as an order parameter, shows a continuous transition at $a=1$ which separates an upstream-dominated ballistic regime ($a<1$) from an ergodic diffusive regime ($a>1$). Through generating-function methods and discrete-time moment recurrences, we derive exact expressions for the propagator and determine the long-time asymptotics of the mean displacement and variance. At the critical point $a=1$, the system exhibits
giant fluctuations, with the variance scaling ballistically up to a logarithmic correction, $\mathrm{Var}(x_T) \propto T^2 / \log T$. These results demonstrate how slowly decaying reorientation probabilities lead to a marginal breakdown of the Central Limit
Theorem, enabling unusually high-variance exploratory dynamics in biased environments.
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Mesoscale and Nanoscale Physics
Deterministic control of the probabilistic phase dynamics in injection-locked spin-torque nano-oscillators
Abderrazak Hakam, Chloé Chopin, Nhat-Tan Phan et al. (+8 more)
Spin-torque nano-oscillators (STNOs) inherently exhibit thermally driven phase fluctuations that render their dynamics truly
stochastic. Here, we demonstrate that, despite this intrinsic randomness, the probability of occupying each phase state can be deterministically and continuously programmed. We experimentally investigate a
vortex-based STNO operating under second-harmonic injection-locking, where the oscillator phase settles into two degenerate attractors separated by $\pi$ and undergoes thermally activated phase jumps. By applying a weak
radio-frequency perturbation at the free-running frequency, we tune the phase-jump rates between the two attractors without suppressing the fluctuations, achieving continuous probability control from the unbiased limit to values approaching 0 or 1. The bias phase selects which attractor is favored while the bias amplitude sets the strength of the imbalance, providing two complementary control knobs within a single nanoscale device. A phase-reduced description based on an effective quasipotential quantitatively accounts for the observations. These results establish injection-locked STNOs as programmable
stochastic elements and provide a hardware primitive for probabilistic computing, Ising machines, and
brain-inspired computing architectures.
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All authors Abderrazak Hakam, Chloé Chopin, Nhat-Tan Phan, Nicolas Mollard, Franck Badets, Louis Hutin, Luana Benetti, Alex S. Jenkins, Ricardo Ferreira, Ursula Ebels, Philippe Talatchian
High Energy Physics (Theory)
Thermodynamic and Topological Phase Transitions of AdS Black Holes with Nonminimal $F^{\alpha\beta}F^{\gamma\lambda}R_{\alpha\gamma}R_{\beta\lambda}$ Coupling
Mehdi Sadeghi and Faramarz Rahmani
The conventional and topological phase transitions of a four-dimensional asymptotically AdS black hole with a non-minimal coupling term $F^{\alpha\beta}F^{\gamma\lambda}R_{\alpha\gamma}R_{\beta\lambda}$ are investigated. Using a perturbative approach to first order in the coupling $\epsilon$, the thermodynamic quantities are derived and the first law and Smarr relation are verified. Intriguingly, while the $\epsilon = 0$ limit yields the standard Reissner–Nordström–AdS black hole belonging to the $W^{1+}$ topological class ($W = +1$), switching on the non-minimal coupling fundamentally transforms the
topology to the $W^{0-}$ class ($W = 0$). This transition occurs while the van der Waals-type first-order phase transition survives in the intermediate region, embedded within the overall Hawking–Page pattern, rendering the system a hybrid black hole thermodynamic system. The coupling $\epsilon$ thus acts as a topological deformation parameter that alters the universal classification of the system, despite the perturbative nature of the solution.
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Classical Physics
On Potentials and Complementary Potentials in One-Dimensional Nonlocal Integral Formulations
Marko Čana{\dj}ija and Ante Skoblar
The present research presents potentials and complementary potentials used in the one-dimensional nonlocal integral formulations. The pure stress and the pure strain nonlocal formulations were considered. While the potential used in the strain driven formulation is well known, the complementary potential has not yet been presented in the literature. The same applies to the stress driven formulation. The equivalent formulations are obtained by resorting to the Legendre transformation, and their equivalence is proved. It is also shown that these results can be used to postulate a novel potential, i.e. a kind of mixed stress-strain potential, which is, however, as ill-conditioned as the pure strain-driven formulation. Finally, an example is given that practically confirms that the stress-driven formulations resulting from the potential and the complementary potential are equivalent.
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Materials Science
Cladding Layer Enhanced GHz Bulk Acoustic Wave Resonance in Sodium Niobate Thin Films on Silicon
Zhi Shiuh Lim, Qibin Zeng, Hui Kim Hui et al. (+17 more)
Bulk acoustic wave resonators (BAWR) and bandpass filters operating at GHz frequency are the workhorse of (Vo-)LTE telecommunication and broadband internet. In line with the Singapore Green Plan 2030 for innovating environmentally friendly products, we fabricated lead-free BAWR with sodium niobate (NaNbO3) piezoelectric on silicon with a high electromechanical coupling factor up to 31.3% operating at ~4 GHz. We disclose our crucial strategy where the NaNbO3 layer is cladded between two thin layers of high band gap
insulators, which satisfies two primary objectives, i.e. leakage current mitigation and crack avoidance. In addition, we also verified the efficacy of reducing
lattice parameters of the cladding layers in promoting vertically distorted tetragonal phase NaNbO3 and producing stronger BAWR signals.
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All authors Zhi Shiuh Lim, Qibin Zeng, Hui Kim Hui, Mengyao Xiao, Tiancheng Luo, Weifan Cai, Shengwei Zeng, Samantha Faye Duran Solco, Baichen Lin, Celine Sim, Zhen Ye, Jinlong Xu, Mingxi Chen, Wei Fu, Chee Kiang Ivan Tan, Seeram Ramakrishna, Yeng Ming Lam, Vincent Chengkuo Lee, Ariando Ariando, Huajun Liu
General Relativity and Quantum Cosmology
Covariant virtual work and the d'Alembert-Lagrange formulation of general relativity
A. Cuevas and C. Ortiz
We develop a covariant virtual work structure and a corresponding d'Alembert-Lagrange principle for spacetime geometry. Within this framework, General Relativity arises as a particular realization of the principle, leading to a covariant d'Alembert-Lagrange formulation in which the Einstein field equations arise from the vanishing of total covariant virtual work on admissible metric variations, rather than from action extremality. The covariant virtual work structure provides a covariant classification of constraint-induced contributions, distinguishing ideal reactions, which perform no virtual work, from non-ideal sectors contribute explicitly to it. The structure extends naturally to one-sided admissibility conditions, yielding a covariant inequality structure. Constraints generate reaction terms. In particular, an isoperimetric constraint produces a cosmological term as an ideal reaction fixed by spacetime averages, so that the cosmological constant emerges as a global parameter determined by admissibility, reflecting an intrinsically nonlocal
geometric origin.
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Quantum Physics
Machine Learning Optimal Quantum Error Correction Thresholds
Dominik Seip, Luis Colmenarez, Markus Schmitt et al. (+1 more)
As
quantum computers remain susceptible to noise, QEC is essential for preserving logical information during computations. However, the performance of QEC codes breaks down beyond certain noise thresholds, revealing fundamental limits on their ability to protect
quantum information. These limits can be characterized using information-theoretic measures such as the coherent information, which quantifies the maximum rate at which logical information can be reliably transmitted through a noisy
quantum channel. In this work, we establish a direct connection between the CI and the binary cross-
entropy loss used when training neural network decoders. Specifically, we show that the CI constitutes a sharp lower bound on the achievable loss for decoders that track logical operators across noisy channels. To this end, we develop a
transformer-based neural network model based on maximum likelihood decoding. We train this network to estimate the CI and evaluate its performance on the surface code under three noise models: code capacity, phenomenological, and
circuit-level noise. Our results demonstrate that the network accurately predicts CI and yields threshold estimates that closely match known theoretical limits. When used as a decoder, the network significantly outperforms the minimum weight perfect matching decoder in terms of logical error rate. We also introduce a novel soft post-selection scheme that independently treats uncertainty in both logical operators and relies on confidence-based filtering of the network's output. We prove that such post-selection strategies, based on the MLD cosets, are optimal, and demonstrate their scalability in terms of both logical error rate and abort probability. These findings establish
transformer-based architectures as powerful tools for QEC and provide the first numerical evidence supporting the optimality and scalability of MLD-based post-selection.
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All authors Dominik Seip, Luis Colmenarez, Markus Schmitt, Markus Müller
High Energy Astrophysical Phenomena
Multiwavelength variability of the high-energy neutrino candidate PKS 0735+178 over three decades
T. Mufakharov, Yu. Sotnikova, V. Vlasyuk et al. (+12 more)
We present the multiwavelength variability of the BL Lac object PKS 0735+178, associated with the high-energy
neutrino event IC211208A. The light curves cover the
radio (1-230 GHz), optical, and
Fermi-LAT $\gamma$-ray bands over a $\sim$30 years time-scale. The light curves are correlated, with delays from 0 to 1200 days increasing towards lower frequencies, consistent with emission from an opacity-stratified jet. The bright
flare after the IC211208A event indicates emission from a compact, optically thick region with enhanced activity and more efficient particle acceleration. Short optical and $\gamma$-ray bursts have been detected very close to the
neutrino event, within a few days. The $\sim$12-day lag between the $\gamma$-ray and optical emissions is detected for the first time, suggesting that the emission regions are not co-spatial. A characteristic variability time-scale of $\sim$10-11 yr is robustly detected in the
radio-mm bands ($\geq3\sigma$), while the optical and $\gamma$-ray data show weaker, shorter-period signals. The independent constraints from the VLBI core-shift measurements and
radio time delays yield consistent estimates of the jet geometry and disturbance propagation, supporting variability governed by jet propagation effects. The long-term modulation is consistent with a slow variation in energy release at the jet base, while individual
flares arise from shocks propagating downstream. Jet precession may contribute to the long-term modulation; however, the required viewing angles are inconsistent with the VLBI constraints, indicating that precession alone cannot explain the observed variability.
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All authors T. Mufakharov, Yu. Sotnikova, V. Vlasyuk, D. Kudryavtsev, A. Pushkarev, A. Mikhailov, M. Khabibullina, Yu. Kovalev, Y. Kovalev, A. Popkov, A. Erkenov, O. Spiridonova, T. Semenova, P. Tsybulev, D. Nezamov
Quantum Physics
Fundamental Irreversibility from Discrete Time
M.W. AlMasri
In 1964, Yu. A. Gol'fand proposed an extension of
quantum mechanics to discrete time, predicting intrinsic non-unitarity and
entropy increase. While historically significant, this formalism predates the modern theory of open
quantum systems. In this work, we rigorously recast Gol'fand's discrete
evolution equation as a Completely Positive Trace-Preserving (CPTP)
quantum channel and derive its continuous-time coarse-grained limit. We demonstrate that the dynamics converge to a specific Lindblad master equation characterized by a fundamental time scale $\tau$, which induces decoherence in both the energy basis and a fundamental operator basis $W$. We analyze the thermodynamic implications using Spohn's
entropy production formalism, proving that the discrete time step induces a strictly positive
entropy production rate driven by the decay of
quantum coherences, thereby providing a microscopic foundation for the arrow of time independent of environmental coupling. Furthermore, we quantify the loss of
quantum coherence via fidelity decay and purity loss, establishing exact constraints for fault-tolerant
quantum computing. We further investigate the impact of this intrinsic decoherence on Discrete Time
Crystals (DTCs), showing that Gol'fand dynamics impose a fundamental lifetime limit on time-translation
symmetry breaking phases. Finally, we utilize precision data from optical
lattice clocks, matter-wave interferometry, and
neutrino oscillations to place stringent upper bounds on $\tau$. Our results constrain the fundamental time discretization to $\tau \lesssim 10^{-26}$ s, significantly tightening previous limits and offering a testable framework for
quantum gravity phenomenology.
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Materials Science
Reversible nonrelativistic magnon spin transport in ferroelastic altermagnets
Haozhou Cai, Jian Wu and Weiyi Pan
Magnons in
antiferromagnetic (AFM)
insulators facilitate low-dissipation, stray-field-free
spin transport. However, achieving nonvolatile, field-free control over
magnon spin currents remains elusive. Here, based on
symmetry analysis, we propose a universal mechanism for the active manipulation of
magnon spin transport via ferroelastic transitions in two-dimensional (2D) altermagnets (AMs)-a class of unconventional AFMs simultaneously exhibiting compensated magnetization and nonrelativistic
spin splitting. We show that these transitions effectively reorient principal
crystal axes and modulate the underlying
magnetic exchange anisotropy. Consequently, this magnetoelastic coupling drives nonrelativistic anisotropic
spin transport that is ferroelastically switchable without the need for external
magnetic fields or Berry
curvature, leading to sign reversals in the
spin Seebeck and
spin Nernst conductivities. We validate this mechanism using first-principles calculations and
spin-model analyses of an AM CoTe2 monolayer. Our findings establish a
symmetry-based magnetoelastic paradigm for the nonvolatile control of
magnon spin transport in 2D AMs, opening new avenues toward energy-efficient, reconfigurable AFM magnonic devices.
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Cosmology and Nongalactic Astrophysics
The local ultraviolet signature of Type Ia supernova environments from HST and MUSE
Lluís Galbany, Cullen Abelson, Alaa Alburai et al. (+17 more)
The local environment of a Type Ia
supernova (SN~Ia) traces the local
stellar-population age (a statistical proxy for the progenitor age),
star formation,
dust, and chemical enrichment that may influence both its light-curve properties and its standardized luminosity. We assemble a homogeneous explosion-site
dataset to test how near-ultraviolet (UV) imaging combined with optical integral-field spectroscopy improves the characterization of SN~Ia environments and their connection to SN~Ia observables. We analyze 340 low-
redshift SN~Ia explosion sites observed with HST/WFC3 in F275W together with matched VLT/MUSE spectroscopy. For each site we measure local photometry and extract a 1~kpc-aperture spectrum, model the
stellar continuum with STARLIGHT in a joint UV+optical fit, derive local
stellar and gas-phase properties, and fit the SN light curves with sncosmo/SALT3-NIR. UV emission is detected at 235 of the 337 sites with valid HST imaging. The UV- and H$\alpha$-based
star-formation-rate surface densities are strongly correlated, with the UV estimates systematically higher by about 0.5 dex. Including the UV constraint in the STARLIGHT fit shifts local luminosity-weighted ages toward older values by a median of $+0.20$ dex for UV detections and $+0.45$ dex for UV non-detections, showing that UV data help break age–
dust–
metallicity degeneracies and substantially alter and tighten the inferred local
stellar-population ages within the adopted modelling framework. Consistently, F275W$-r$ is very strongly correlated with the joint-fit
stellar age. Within the 169-SN~Ia calibration sample, the joint
stellar age, the H$\alpha$ specific
star-formation rate (sSFR), and the UV sSFR all correlate strongly with the SALT3 stretch parameter $x_1$, with significances above $6.8\sigma$. (abridged)
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All authors Lluís Galbany, Cullen Abelson, Alaa Alburai, Joseph P Anderson, Yago Ascasibar, Chris Ashall, Carles Badenes, Chris Burns, Èlia Diéguez Gurnés, Albert García Soto, Claudia P. Gutiérrez, Eric Y. Hsiao, Hanindyo Kuncarayakti, Andrew J. Levan, Jospeh Lyman, Mark M. Phillips, Sebastian F. Sánchez, Ramon Sanfeliu, Maximilian Stritzinger, Danny Steeghs
Quantum Physics
StableShots: Online Shot Stopping for Quantum Circuit Execution
Giuseppe Bisicchia, Alessandro Bocci, Ernesto Pimentel et al. (+1 more)
Quantum circuit execution estimates output distributions by repeated measurements, yet developers commonly choose a fixed shot budget before execution. This static choice is brittle: low budgets can under-sample the distribution, while high budgets waste measurements. In this paper, we present StableShots, a black-box online stopping rule for static
quantum circuits. The method executes a fixed
circuit in small batches, monitors the total-variation distance between cumulative empirical distributions, and stops after repeated evidence of local stability. We evaluate StableShots on 180 QSimBench traces spanning six
circuit families, six sizes from 4 to 14
qubits, and five noisy IBM simulated backends. With validation-only calibration and 100 repeated backend-holdout splits, the selected configuration reaches TVD <= 0.05 on all held-out test evaluations with median 7,650 shots, whereas fixed-shot baselines either fail more often or spend substantially more shots.
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All authors Giuseppe Bisicchia, Alessandro Bocci, Ernesto Pimentel, Antonio Brogi
Instrumentation and Methods for Astrophysics
Distributed Peer Review at ALMA: An Empirical Comparison with Panel-Based Review
John M. Carpenter and Andrea Corvillón
Large astronomical observatories are increasingly adopting distributed peer review (DPR) to manage growing proposal volumes, yet empirical comparisons with panel-based systems remain limited. Beginning in 2021 (Cycle 8), the Atacama Large Millimeter/submillimeter Array (ALMA) transitioned to DPR for the majority of proposals, with DPR applied to nearly all proposals from Cycle 9 onward. Under DPR, each Principal Investigator (PI) designates a reviewer to evaluate a set of proposals without collective discussion. This study analyzes over 20,000 proposals and 160,000 reviews spanning 13 cycles to assess the impact of this change. We find that DPR largely reproduces the systematic ranking trends observed in panel evaluations across PI demographics, technical characteristics, and scientific areas, consistent with panel outcomes both before and after discussion. Scientific diversity among the top-ranked proposals is similar between DPR and post-discussion panel rankings. Individual proposal ranks show substantial dispersion under both DPR and panel assessments prior to discussion, with discussion only partially reducing this variance. The observed dispersion therefore reflects intrinsic variation in reviewer judgments rather than a byproduct of the distributed process itself. In Cycle 12, reviewers rated the majority of DPR written comments as high or adequate quality, with no dependence on reviewer career stage. However, 10% of reviews were rated as low quality, highlighting the challenge of maintaining quality standards across the approximately 16,000 reviews produced each cycle. Overall, our results indicate that DPR reproduces the population-level ranking structure obtained in panel review, despite differences in review mechanics and the role of discussion.
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Instrumentation and Methods for Astrophysics
Deep RL for Fast Long-Horizon Operations Scheduling on NASA's Carruthers Geocorona Observatory Mission
Alex Zhang, Jackson Craig and Lara Waldrop
Spacecraft operations scheduling is a highly constrained, long-horizon combinatorial optimization problem that traditionally relies on heuristics, constraint programming, or manual planning. We present a scalable deep reinforcement learning framework developed and deployed for NASA's Carruthers Geocorona Observatory mission. Our framework introduces a macro-action abstraction known as activity blocks coupled with dynamic action-masking to navigate the intractably large search space and strictly enforce complex power, thermal, and instrument constraints. The resulting architecture generates globally feasible schedules with overwhelming probability, establishes operational trust, and executes a full training cycle in under six hours, circumventing the need for policy robustness by enabling rapid, on-demand retraining. Further, resulting schedules outperform baseline heuristics in scheduled science quality. The deep reinforcement learning framework was deployed as the default operational scheduler for the Carruthers Geocorona Observatory mission from the outset of the mission, demonstrating that deep reinforcement learning can be trusted for real spacecraft operations under complex, evolving constraints.
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Classical Physics · Cross-listed from math.AP
How to Cook a Soft-Boiled Egg Optimally: A Laplace-Transform Solution of a Two-Domain Heat Equation
Matthew Lorig
We study the problem of cooking the yolk and albumen of a hen's egg to their respective optimal temperatures of $T_Y^* = 65^\circ$C and $T_W^* = 85^\circ$C, subject to the requirement that neither temperature ever exceed its target at any time during cooking, since temporary overshoot still overcooks the egg even if the final reading is correct. We model the egg as a two-domain sphere with distinct thermal diffusivities, and take the Laplace transform of the heat equation in each domain, reducing the problem to a $3 \times 3$ linear system in the transform variable $s$ with
hyperbolic-trigonometric solutions. The resulting transform is inverted numerically via Talbot's method and validated against a finite-difference solver. A single boiling phase cannot satisfy the no-overshoot requirement: the thin outer albumen heats far faster than the insulated yolk and necessarily overshoots $T_W^*$ before the yolk approaches $T_Y^*$. We show that a three-phase protocol resolves this: a sous-vide pre-soak at exactly $65^\circ$C (which cannot overshoot since the bath temperature equals the target), a short boil to bring the albumen toward $T_W^*$, and an ice-water bath that arrests the albumen's residual overshoot while residual heat continues raising the yolk to its target. Optimizing the phase durations gives $17.26$ minutes of sous-vide, $66$ seconds of boiling, and an ice bath, achieving both targets at $T^* \approx 20.67$ minutes with neither constraint violated at any time. This compares favorably with the periodic protocol of Di Lorenzo et al. (2025), which requires 32 minutes and misses both targets substantially.
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Applied Physics
Structure-driven analog optical control in ion-pumped SrFeO$_{3-\delta}$ thin-film devices
Alicia Ruiz-Caridad, Paul Nizet, Francesco Chiabrera et al. (+4 more)
Electrochromic devices (ECDs) offer a compelling route toward low-power, non-emissive optical modulators with nonvolatile states. However, their widespread implementation is hindered by limitations in operating voltage, switching speed, color tunability, and long-term stability. Mixed ionic-electronic conductors (MIECs) provide a promising alternative platform, enabling optical modulation through ion-driven redox and structural transformations. Oxygen-based MIECs offer enhanced durability, environmental robustness, and compatibility with
oxide electronics and silicon photonics, yet remain largely underexplored for electrochromic and photonic applications. Here, we demonstrate structure-driven analog optical control in an ion-pumped SrFeO$_{3-\delta}$ thin-film device by undergoing reversible oxygen-driven phase transitions between brownmillerite and perovskite structures. Phase transition is accompanied by pronounced changes in its electronic structure and optical constants. By harnessing these ion-induced structural transformations and integrating an optically passive Al$_2$O$_3$ interference layer, we achieve continuous and reversible modulation of optical transmittance and color. These results provide a general framework for ion-driven analog photonic and electrochromic devices and highlight the potential of oxygen-based MIECs for next-generation ionochromic systems compatible with silicon-based photonic platforms.
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All authors Alicia Ruiz-Caridad, Paul Nizet, Francesco Chiabrera, Xavier Vea, Philipp Langner, Alex Morata, Albert Tarancon
Materials Science
Bridging Phase-Field Model and Deep Learning for Predicting 2D and 3D Microstructure Evolution in Ternary Alloys
Owais Ahmad, Aravind K, Naveen Kumar et al. (+3 more)
We develop a hybrid framework that integrates a phase-field model (PFM) with an
attention-enhanced deep learning (DL) architecture to study ternary spinodal dealloying, a sophisticated self-organization approach used to fabricate three-dimensional bicontinuous, hierarchical nanoporous materials. The study captures three distinct phase-separation mechanisms that emerge during the early stages of spinodal decomposition in both two and three dimensions. The DL workflow consists of three key components: (i) a dimensionality-reducing autoencoder that provides compact representations of high-resolution microstructure images (256x256x3), (ii) an
attention-augmented convolutional long short-term
memory (ConvLSTM) network that learns complex spatiotemporal correlations governing microstructure
evolution, and (iii) a novel slice-by-slice strategy that enables extension of the model to three-dimensional systems (128x128x128x3). We further demonstrate a hybrid simulation strategy in which PFM accurately captures rapid early-stage microstructure
evolution, while the DL model efficiently predicts late-stage coarsening dynamics. The trained DL model achieves remarkable predictive accuracy, maintaining fidelity up to 400 timesteps ahead and generalizing to compositions outside the training distribution. By bridging the physical fidelity of PFM with the computational efficiency of DL, this framework establishes a robust platform for predictive modeling of microstructure
evolution in complex multicomponent systems.
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All authors Owais Ahmad, Aravind K, Naveen Kumar, T.A. Abinandanan, Somnath Bhowmick, Rajdip Mukherjee
Cosmology and Nongalactic Astrophysics
Dark Matter as an Inflationary Relic in Warm Inflation
Swagat S. Mishra, Umang Kumar, Suratna Das et al. (+1 more)
Warm inflation is usually expected to completely deplete the inflaton condensate by dissipating its energy into radiation. We show that this expectation fails in a simple and observationally viable regime. In a strongly dissipative warm inflationary scenario, the dissipative ratio, $Q=\Upsilon/(3H)$, can fall rapidly after the end of inflation as the system approaches radiation domination, thereby suppressing further energy transfer to the thermal bath. This leads to a residual inflaton condensate, which subsequently evolves as an effectively non-dissipative scalar field. For potentials with a stable quadratic minimum, this remnant inflaton manifests as a cold dark matter component. We establish this mechanism for the minimal renormalizable potential, with a dissipative coefficient $\Upsilon\propto T^3$. In this case, current cosmological data allow strong dissipation while leaving the inflaton mass weakly constrained by inflationary observables. The observed dark matter abundance then fixes its mass to be $m \approx 0.02\,{\rm MeV}$, while larger masses overclose the Universe. The transition to matter-like scaling occurs well before BBN, avoiding a long-lived inflaton dark radiation component. Relic inflaton dark matter therefore turns the post-inflationary dynamics of warm inflation into a new late time constraint on its parameter space.
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All authors Swagat S. Mishra, Umang Kumar, Suratna Das, Varun Sahni
Plasma Physics
Resonant Pitch-Angle Scattering Of Runaway-Electrons by Externally-launched Helicon Waves in the DIII-D Tokamak
Hari Choudhury, Jeffrey Lestz, Carlos Paz-Soldan et al. (+12 more)
Resonant wave-particle interactions between externally launched helicon waves (also known as whistler waves) and runaway electrons (REs) have been demonstrated on the DIII-D tokamak. In this work we extend the initial results reported in Choudhury, H. et al. Phys. Rev. Lett. 136, 025101 (2026) by exploring the effects of
antenna alignment with the edge
magnetic field, toroidal wave propagation direction, and coupled power on RE scattering in the quiescent RE experimental scenario. Two distinct experimental configurations have been investigated: one in which the
antenna aligns well with the edge background
magnetic field, known as the ideal
antenna configuration, and one with misalignment, known as the non-ideal case. Previously, it had been found that helicon power in the ideal
antenna configuration prevented RE growth despite the normalized toroidal electric field remaining high enough to drive exponential RE growth in the absence of helicon power. In this paper, we show that scattering via the normal Doppler resonance (n=1) effectively limits the growth of the RE population in both the ideal and non-ideal
antenna configurations, with evidence of a power threshold in the latter case. In contrast, launching waves that favour the anomalous Doppler resonance (n=-1) is observed to enhance rather than reduce the RE population. In addition, fast
magnetic measurements reveal rising-tones in the 30-60 MHz range during helicon-off periods, which are not observed prior to helicon power. Finally, the challenges of using launched helicon waves to scatter post-disruption RE beams are discussed. Collisional damping and a large
vacuum gap between the
plasma and
antenna on the outboard side present significant obstacles to helicon waves propagating into the
plasma core.
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All authors Hari Choudhury, Jeffrey Lestz, Carlos Paz-Soldan, Alexander Battey, Nils Leuthold, Andrey Lvovskiy, Claudio Marini, Jayson Barr, William Heidbrink, Donald Spong, Shawn Tang, Bart Van Compernolle, Qile Zhang, Yanzeng Zhang, Xianzhu Tang
Mesoscale and Nanoscale Physics
Superconducting cavity probes sliding ferroelectricity in small-angle twisted WSe$_2$
Krishnendu Maji, Supriya Mandal, Sriram H. et al. (+8 more)
Ferroelectricity is a property of materials that exhibit spontaneous charge polarization. Ferroelectricity in 2D materials is interesting because of their applications in
memory devices and field-effect transistors. Recently, a new type of ferroelectricity, known as sliding ferroelectricity, has been discovered, in which parallel-stacked
bilayers of hexagonal boron nitride (hBN) or transition metal dichalcogenides (TMDCs) develop an out-of-plane electric polarization. In this work, we probe the polarization of small-angle parallel stacked WSe$_2$ by measuring its high-frequency AC response, achieved by
embedding it into a half-wave superconducting coplanar waveguide cavity. We observe a hysteretic response in the capacitance of the stack and quality factor of the cavity, confirming ferroelectric switching in the system. Our results further reveal relaxation effects associated with ferroelectric domain-wall motion. This cavity-based technique has potential applications in probing domain-wall dynamics in a ferroelectric system at high frequencies.
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All authors Krishnendu Maji, Supriya Mandal, Sriram H., Rishiraj Rajkhowa, Malhar Date, Sayani Pal, Meghan P. Patankar, Kenji Watanabe, Takashi Taniguchi, Vibhor Singh, Mandar M. Deshmukh
Strongly Correlated Electrons
Field-tunable quadruple-$Q$ states driven by momentum-space frustration
S. Hayami
Multiple-$Q$ magnetism in itinerant electron systems enables complex
spin crystals and noncoplanar textures even in centrosymmetric settings. We study a minimal momentum-space
spin model on a square
lattice with four
symmetry-related ordering wave vectors, including bilinear and biquadratic interactions under an out-of-plane
magnetic field. Using simulated annealing, we obtain the field-dependent phase diagram and identify successive transitions among single-$Q$, double-$Q$, and multiple inequivalent quadruple-$Q$ states. The quadruple-$Q$
manifold exhibits rich internal structures: the states sharing the same wave vectors differ in phase locking, amplitude distribution, and noncoplanarity, leading to distinct real-space textures and scalar
spin chirality patterns. Our results demonstrate that momentum-space frustration and biquadratic coupling provide an efficient route to stabilizing diverse quadruple-$Q$
spin crystals, offering a general framework for higher-order
spin textures in centrosymmetric itinerant magnets.
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Other Condensed Matter
Thermodynamic stability and structural transitions in virus-host networks
A. Rovenchak and M. Husiev
Understanding virus-host interactions is crucial for predicting the stability of networks under various perturbations. In this study, we present an analysis of virus-related networks for several organisms (Homo sapiens, Mus musculus, Gallus gallus), encompassing directed and weighted connections. We compute a range of network parameters, including topological characteristics and thermodynamic quantities derived from adjacency spectra, to gain insights into the structural robustness and dynamic behavior of the networks. To assess stability, we model two distinct node removal scenarios: targeted elimination of the most influential nodes and random removal. Our findings reveal transition-like behavior in spectral thermodynamic functions and characteristic changes in structural measures, contributing to evaluating the potential of a thermodynamic framework for studying virus-host networks and advancing a deeper understanding of their dynamics.
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Mesoscale and Nanoscale Physics
Effect of weak positional disorder on the miniband structure of spherical quantum dot chains
R. Ya. Leshko
A theoretical framework is developed for the electron miniband structure in one-dimensional chains of spherical
quantum dots subjected to weak positional disorder. Within the tight-binding approximation combined with the effective-medium approach, the
stochastic fluctuations of the inter-dot spacing are mapped onto the renormalization of the key
Hamiltonian parameters: the hopping integral $ B $, the overlap integral $ Q $, and the on-site energy shift $ M $. Analytical expressions for these disorder-renormalized parameters are derived by performing an ensemble average over a narrow Gaussian distribution of positional deviations ($ \sigma \ll a $). The resulting generalized dispersion relation shows that weak positional disorder causes a broadening of the minibands. Specifically, for typical fabrication fluctuations $\sigma = 0.1\,a $, the miniband width increases by 8-12% (depending on the mean inter-dot distance $a$). At the same time, the sensitivity of the miniband width to disorder decreases rapidly with increasing
lattice period due to the exponential decay of the electron wave functions. In the considered weak-disorder regime, the Anderson localization length significantly exceeds the
lattice constant, so the miniband states remain delocalized.
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