Computational Physics
Constitutive modelling of magneto-active polymers at finite strains: A survey
Abhishek Ghosh, Chennakesava Kadapa and Mokarram Hossain
Magneto-active
polymers (MAPs) are field-responsive soft composites whose mechanical behaviour can be actively modified by external
magnetic fields. Their ability to exhibit field-induced stiffening, magnetostriction, anisotropy and rate-dependent response makes them attractive for sensors, actuators, adaptive structures, vibration-control devices and soft robotic systems. This article presents a structured survey of constitutive modelling approaches for MAPs at finite strains. The review traces the development from early semi-empirical descriptions to thermodynamically consistent nonlinear continuum theories, with particular
attention to isotropic and anisotropic magnetoelastic constitutive models, invariant-based and spectral representations, variational and polyconvex frameworks, microstructurally motivated models, dispersed-chain descriptions and magneto-viscoelastic theories. The principal constitutive variables, energy functions, coupling mechanisms and physical assumptions underlying the main models are discussed. The survey shows that constitutive modelling of MAPs has developed into a broad family of nonlinear, anisotropic and dissipative frameworks capable of describing versatile behaviours observed experimentally. Important challenges remain in resolving thermo-magneto-mechanical coupling and microstructure-sensitive effects, identification of parameters, validation of models as well as robust and efficient implementation on computers.
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Astrophysics of Galaxies
The Incidence of Large Ionized Bubbles at Redshift 13
Peter Ziwei Hu, Massimo Stiavelli and Colin Norman
Ionized bubbles around the first
galaxies connect early
galaxy growth, ionizing
photon escape, intergalactic-medium
topology, Ly$\alpha$ visibility, 21~cm structure, and reionization timing. We model the incidence of
galaxy-driven ionized bubbles at $z\approx 13$ using JWST UV luminosity functions, taking the Ly$\alpha$ source reported by Witstok et al. as a
benchmark for the relevant scale. We quantify regions with comoving radius $R\ge 2.5$~cMpc through their sky surface density $\Sigma_{\ge 2.5}$. For our continuously active fiducial case, using the Donnan et al. UVLF with $f_{\mathrm{esc}}=0.2$, $\log\xi_{\mathrm{ion}}=25.5$, $f_{\mathrm{active}}=1$, and $C=3$, we find $\Sigma_{\ge 2.5}\simeq 8.10\times 10^{-3}$ arcmin$^{-2}$ per $\Delta z=1$. For $f_{\rm active}=0.2$ or $f_{\rm time}=0.2$ with 10~Myr mean on-times, the incidence falls by factors of 4.1 and 2.9, respectively; longer correlated episodes strengthen the tail. Merging overlapping spheres raises the fiducial incidence by $9.5\%$. The simulations show that Witstok-sized regions can arise in UVLF-calibrated
galaxy-driven models. This is a population-level statement, and the specific Witstok source may still require unusual effective ionizing efficiency, recent fading or burstiness, or a non-
stellar ionizing contribution.
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High Energy Physics (Phenomenology)
Search for a Time-Dependent Z' Resonance in the Dimuon Channel
Marlon P. Brade, Jeremiah D. Juevesano, Venus Abbegaile S. Carbonel et al. (+3 more)
We present a time-domain search strategy for resonances with periodically varying masses in high-energy
collider data. Conventional resonance searches rely on time-integrated event samples and are therefore insensitive to signals whose properties evolve during data taking. To address this limitation, we develop a two-dimensional unbinned likelihood framework in invariant mass and time, allowing the reconstruction of signals that trace nontrivial trajectories in the $(m,t)$ plane rather than appearing as stationary resonances. As a
benchmark scenario, we consider a $Z'$
boson arising from a gauged $U(1)_{B-L}$ extension of the Standard Model and introduce a phenomenological model in which the mediator mass undergoes periodic temporal modulation. The resulting signal manifests as a resonance whose position changes with time, producing distinctive patterns that are inaccessible to conventional analyses based solely on invariant-mass information. The method is implemented using dimuon events from the CMS Open Data corresponding to the Run~G data-taking period at $\sqrt{s}=13~\mathrm{TeV}$, with an integrated luminosity of $7.54~\mathrm{fb}^{-1}$. We derive upper limits on the gauge coupling $g'$ as a function of the $Z'$ mass for several choices of the modulation amplitude. The results demonstrate that incorporating temporal information can enhance sensitivity relative to standard time-integrated searches, particularly in regions with sufficient signal statistics.
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All authors Marlon P. Brade, Jeremiah D. Juevesano, Venus Abbegaile S. Carbonel, Karen E. Bustamante, Dennis C. Arogancia, Jan Mickelle V. Maratas
High Energy Astrophysical Phenomena
A MUSE View of the Optical Torus within the Supernova Remnant 1E 0102.2-7219
Janette Suherli, Samar Safi-Harb, Ivo R. Seitenzahl et al. (+6 more)
We present new MUSE Narrow Field Mode with Adaptive Optics observations of the optical
torus surrounding a Central Compact Object (CCO) candidate within the oxygen-rich
supernova remnant 1E 0102.2-7219 (E0102) located in the Small Magellanic Cloud. These data provide nearly an order-of-magnitude improvement in spatial resolution over previous MUSE Wide Field Mode observations. The improved spatial resolution resolved the previously identified
torus into a cavity-like structure with a sharply defined inner edge and diffuse, outer filamentary substructure. The emission shows continuous velocity connectivity, broad intrinsic line widths, and co-spatial contributions from neutral and partially ionized species, including O I, Ne I, [O I], [O II], and [O III]. Spatially resolved line-ratio maps indicate that the emission arises from a multiphase, non-
equilibrium medium rather than a single homogeneous component. Comparison with photoionization and shock models shows that no single-component model within the explored parameter space can simultaneously reproduce both the strong neutral and high-ionization diagnostics, indicating that multiple physical conditions must coexist. We favor an interpretation in which shocks propagating through density inhomogeneities in the ejecta shape the observed morphology and excitation, while also considering alternative mechanisms linked to the central source, binary
evolution, or interaction with an embedded object within the remnant.
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All authors Janette Suherli, Samar Safi-Harb, Ivo R. Seitenzahl, Frédéric P. A. Vogt, Parviz Ghavamian, Ralph Sutherland, Chuan-Jui Li, Ashley J. Ruiter, Gilles Ferrand
Solar and Stellar Astrophysics
Characterizing Orbital Parameters of Hot Subdwarf Binaries with Multiple Spectroscopic Surveys
XInlin Zhao, Song Wang, Zhenxin Lei et al. (+5 more)
Hot subdwarfs (HSDs) provide critical insights into the physical mechanisms governing binary
evolution. In this work, we conduct a systematic analysis of 157 HSDs, selected from
Gaia EDR3 and characterized using multi-survey spectroscopic data. Atmospheric parameters of these HSDs are derived via a convolutional neural network (CNN) method and template-matching method. Based on the atmospheric parameters from CNN method, these HSDs exhibit a median mass of $0.45^{+0.19}_{-0.17} M_{\odot}$ and radius of $0.18^{+0.04}_{-0.05} R_{\odot}$, consistent with earlier work. Orbital parameters of 23 systems are determined through the fitting of radial velocity data and light curves, with 11 of them being new solutions. We find that reflection-dominated binaries typically have periods longer than 0.1 d and host low-mass main-sequence companions ($\sim$ 0.2 $M_{\odot}$) with rotation-inflated radii. In contrast, binaries including an HSD and a white
dwarf show very short periods ($P < 0.2$ d), with the closest systems hosting more massive white
dwarfs. Most of these systems share a similar mass–period distribution with that of post-common-envelope binaries, supporting a common-envelope origin.
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All authors XInlin Zhao, Song Wang, Zhenxin Lei, Yangyang Dong, Buhui Lv, Chuanjie Zheng, Xiaohong Yang, Jifeng Liu
Statistical Mechanics
Brownian gyration of an inertial ellipsoid
Soham Dutta and Arnab Saha
Recent studies on Brownian gyration (BG) have focused primarily on spherically symmetric particles under overdamped conditions. To explore BG in the underdamped regime with a spherically asymmetric particle, we investigate the inertial dynamics of a microscopic ellipsoid in a dissipative medium. The particle is confined in a spherically asymmetric trap and simultaneously coupled to two distinct thermal reservoirs. This configuration drives the system into a nonequilibrium steady state (NESS) characterised by BG, which is quantified by the mean and fluctuation of the particle's specific angular momentum. Using inertial Langevin dynamics, we systematically analyze how this microscopic gyration depends not merely on the trap asymmetry and temperature difference, but also on the particle's intrinsic physical properties like shape and axial orientation, besides inertia. Our study uncovers fundamental differences between the gyration of spherical and non-spherical particles in overdamped as well as underdamped conditions, at microscopic scales. These findings provide key insights for optimizing Brownian gyration across a broader landscape of experimentally tuneable parameters.
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Cosmology and Nongalactic Astrophysics
Does DESI prefer Damped Oscillating Dark Energy over Cosmological constant?
Saddam Hussain, Simran Arora, Qiang Wu et al. (+1 more)
We investigate a dark-energy equation of state governed by a damped harmonic oscillator equation, admitting underdamped, critically damped, and overdamped solutions. Confronting the model with Planck CMB distance priors, DESI BAO, BBN,
cosmic chronometers, and three Type~Ia
supernova compilations, we find that the data select an underdamped solution yielding $H_0 = 70.9 \pm 1.1$ km/s/Mpc with DES-Dovekie and $H_0 = 72.0^{+1.4}_{-2.1}$ km/s/Mpc with Union3, without any local $H_0$ prior. These higher values of $H_0$ arise along the $\Omega_{\rm m}$–$H_0$ degeneracy direction while the sound horizon remains nearly unchanged at $r_{\rm d} \simeq 145$~Mpc, indicating that the enhancement of the late-time expansion rate is a geometrical effect that does not address the early-time calibration of $r_{\rm d}$. In contrast, the Pantheon+ compilation selects a near-critically damped solution with a prior-limited positive $w_0$ and $H_0 = 66.23 \pm 0.85$ km/s/Mpc, highlighting the sensitivity of the model to the low-
redshift distance information encoded in the different
supernova compilations. The
Bayesian evidence relative to $\Lambda$CDM is inconclusive for the DES-Dovekie and Union3 combinations, whereas Pantheon+ shows a strong preference for the damped-oscillator model, driven by the departure from $w=-1$ at $z\lesssim0.1$.
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All authors Saddam Hussain, Simran Arora, Qiang Wu, Tao Zhu
Quantum Physics
Kinematic properties of the Pauli equation
E.E. Perepelkin, B.I. Sadovnikov, N.G. Inozemtseva et al. (+1 more)
Based on the Wigner-Vlasov formalism, this paper investigates the kinematic properties of the Pauli equation. It is shown that the probability current associated with the Pauli equation can be represented as a superposition of two currents with certain expansion coefficients. Each of these currents corresponds to a particular component of the spinor. The expansion coefficients effectively serve as weighting functions that determine the probability contribution of the corresponding spinor component. Therefore, each
spin projection corresponds to its own probability flux. A new system of the Hamilton-Jacobi equations and also a system of motion equations in electromagnetic fields are obtained, taking into account the interaction between the
spin and the
magnetic field. To illustrate how these equations can be applied we have investigated the
quantum system kinematics in detail using an exact solution of the Pauli equation in the presence of a uniform
magnetic field and an asymmetric quadratic potential.
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All authors E.E. Perepelkin, B.I. Sadovnikov, N.G. Inozemtseva, V.A. Svetovidov
Mesoscale and Nanoscale Physics
Beyond the interface: Persistent Hopping Transport and Frequency Dispersion in Strong-inversion Cryogenic MOSFETs
Keito Yoshinaga, Wataru Miyagi, Ryo Toyoshima et al. (+2 more)
Cryogenic complementary metal-
oxide-
semiconductor (cryo-CMOS) technology is essential for
quantum computing interfaces, which require precise modeling of dynamic device behavior. The output impedance of MOS field-effect transistors (MOSFETs) is frequency dependent, which has been conventionally attributed to extrinsic parasitics. Here, we report an intrinsic frequency dispersion in the channel impedance of cryogenic MOSFETs that persists deep into the strong-inversion region. Through a Cole-Cole analysis, we characterize this dispersion as a depressed semicircle in the impedance plane and attribute its behavior to variable-range hopping through band-tail localized states. Unlike conventional models where band-tail states are confined to the
oxide interface, we demonstrate that in MOSFETs with high channel doping the band-tail states are induced by ionized
impurities and distributed throughout the depletion region. Our paradigm accounts for frequency dispersion under strong inversion. This work demonstrates that ionized-
impurities-induced hopping governs the dynamic response of cryo-MOSFETs channel impedance even when drift conduction dominates, offering critical insights for accurate small-signal modeling and high-frequency cryo-CMOS
circuit design.
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All authors Keito Yoshinaga, Wataru Miyagi, Ryo Toyoshima, Munehiro Tada, Ken Uchida
Solar and Stellar Astrophysics
Application of the coherent structure tracking to solar Doppler maps to determine horizontal velocity fields at the Sun's surface
M. Sampoorna, T. Roudier and F. Paletou
Coherent Structure Tracking (CST) is a technique for determining the
solar surface horizontal flows at high spatial and temporal resolution by tracking the proper motion of granules. CST has been traditionally applied to
solar intensity images in the continuum, which clearly depict the granular patterns. However,
solar granulation is also visible in the Dopplergrams. We aim to show that CST can be applied to
solar Dopplergrams to derive the
solar surface horizontal velocity fields with the same level of confidence as those determined by CST on intensity images. For this purpose, we apply the CST to continuum intensity images and Dopplergrams obtained from SDO/HMI and also from a numerical simulation of granulation. We then compare the resulting
solar surface horizontal velocity fields and their derivatives for different time windows. Pearson's linear global correlation coefficient (GCC) between the horizontal velocity fields determined from CST on Doppler and on intensity images of a relatively less active Sun is about 73% for a 30 min time average, while the corresponding local correlation coefficient (LCC) near the disk center is about 80%. For the divergence of the horizontal velocity field, we obtain a GCC of 72% and a near disk center LCC of 84%. The curl of the horizontal velocity field being more noisy exhibits somewhat reduced GCC and LCC. These coefficients increase with increasing time window. A similar trend is exhibited by Spearman's and Kendall's rank-order correlation coefficients, although they are somewhat smaller in value. The different correlation coefficients slightly decrease for magnetically more active Sun with sunspots or emerging pores in a plage region. A high correlation is obtained between the horizontal flows derived by applying CST to intensity and vertical velocity maps from a numerical simulation.
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Mesoscale and Nanoscale Physics
Anomalous Pairing Currents and a Second Topological Edge Channel in Bosonic Lattices
Chitrak Bhadra, Ángel Rivas and Miguel A. Martin-Delgado
We show that bosonic pairing opens a second
chiral current channel on a 2D kagome
lattice, absent from any particle-conserving model. From the continuity equation, we derive both a hopping current and an anomalous pairing current on the
lattice, and predict
chiral circulation in bulk-gapped phases with integer para-
unitary Chern numbers, as well as a phase-sensitive leakage ratio, $\Lambda_{\cal I}$, for the pairing current around a defect. This ratio can be tuned from confined to strongly anomalous regimes at fixed
topology. The two channels differ microscopically: the hopping current is sourced by the on-bond single-particle coherence, whereas the pairing current is sourced by the off-site anomalous coherence, whose spatial range is governed by the BdG pairing gap rather than by the single-particle gap. This separation produces distinct defect-induced signatures in real space, identifies a regime in which bulk
topology and anomalous edge response coexist with no analogue in particle-conserving matter, and is directly testable in driven photonic
lattices and superconducting-
circuit arrays.
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Strongly Correlated Electrons
Flat-Band Stoner Instability and Peierls-Phase Origin of the Transdimensional Anomalous Hall Effect in Rhombohedral Graphite
Yang Zhou
A “transdimensional” anomalous
Hall effect (TDAHE), where both in-plane ($\Bpar$) and out-of-plane
magnetic fields produce hysteretic
Hall signals, was recently observed in nine-layer rhombohedral graphite~\cite{Li2026Nature}. We present a microscopic theory attributing the TDAHE to a flat-band Stoner instability coupled to Peierls-phase gap modulation. The flat-band density of states satisfies the Stoner criterion $U\rho(\varepsilon_F) > 1$~\cite{Bultinck2020}, driving a
spin-valley-locked ferromagnet whose valley polarization $\eta$ breaks time-reversal
symmetry and generates an intrinsic anomalous
Hall conductivity (AHC). The orbital $g$-factor $g_{\mathrm{orb}} = e d_0 v_F (N{-}1)/2 \propto (N{-}1)$ then lets $\Bpar$ modulate the gap, producing the transdimensional response $\propto \eta$. A self-consistent $2N$-band Hartree-Fock calculation yields complete valley polarization ($\eta \to 1$) below a mean-field transition $T_c^{\mathrm{MF}} \approx 2.2$~K, reduced by 2D-Ising critical fluctuations to the experimental $T_c \approx 1.6$~K, with $R_{xy} \approx 1.5$~k$\Omega$. Because both
Hall responses are carried by one order parameter $\eta$, they share a single $T_c$, as observed; $T_c$ is governed by the Stoner product $U\rho$ and is insensitive to the intervalley exchange, which only gates whether the valley-polarized phase forms, so the exchange strength is not a fitted parameter. Beyond reproducing $R_{xy}$, $T_c$, and the phase window, the theory predicts a sharp onset of valley polarization between $N = 7$ and $N = 9$, a
symmetry selection rule fixing the crescent
Fermi surface to the $m{=}1$ nematic channel, and a transdimensional-to-conventional
Hall ratio $\sigmaPHE/\sigmaAHE^{\mathrm{tot}} = g_{\mathrm{orb}}\Bpar/m$ independent of $\eta$ and $U$. The $Z$-independence of the intrinsic AHC is verified within dynamical mean-field theory.
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Disordered Systems and Neural Networks
Hyperuniform charge distributions and phase transitions in a generalized Aubry-André model
Lujia Xiang, Junmo Jeon and Shiro Sakai
We show the existence of distinct inhomogeneous charge distributions and a phase transition between them in aperiodic
fermion systems. Using a generalized Aubry-André model as an example, we obtain various types of charge distributions, which we classify by means of hyperuniformity, a general mean to quantify and classify the global uniformity of spatial distributions. Examining various cases of filling fraction and potential strength and shape, we find that the many-body charge distribution in this model is always hyperuniform, i.e., showing an anomalously suppressed long-range fluctuation, while its hyperuniformity class depends on the localization properties of the states around the
Fermi energy, irrespective of those of high-energy states. Namely, the change in the localization properties of these single-particle states leaves a signature in the hyperuniformity class of many-body charge distribution. We further show a change of the hyperuniformity class corresponds to a phase transition between inhomogeneous many-body states, and that it is of the third order.
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Physics and Society
Public transit gains and spatially uneven travel demand changes after NYC congestion pricing
Donghang Li, Dingyi Zhuang, Yunlin Li et al. (+5 more)
New York City implemented the nation's first cordon-based congestion pricing program in January 2025, providing an opportunity to evaluate how system-wide urban mobility responds to large-scale pricing interventions. Because such policies generate spillovers across modes and locations, credible control groups are difficult to construct. We address this challenge using time series foundation models to generate probabilistic counterfactual demand forecasts with calibrated uncertainty. Applying this framework to bus, subway, and aggregate trip volume data, we find that post-policy bus and subway ridership increased significantly relative to expected no-policy demand, while overall travel demand decreased modestly. The effects are spatially heterogeneous: while reductions in overall travel demand are concentrated within the Congestion Relief Zone, transit gains extend beyond Manhattan's core. Socio-demographic analyses further reveal uneven adaptation across neighborhoods, highlighting spatial equity implications. Our framework provides a scalable approach for the uncertainty-aware evaluation of system-wide urban interventions when clean control groups are unavailable.
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All authors Donghang Li, Dingyi Zhuang, Yunlin Li, Chenan Shen, Nina Cao, Yunhan Zheng, Shenhao Wang, Jinhua Zhao
Mathematical Physics · Cross-listed from math.CO
Skew column RSK dynamics and the box-ball system
Takashi Imamura, Matteo Mucciconi, Tomohiro Sasamoto et al. (+1 more)
The Fomin local rules for Schensted column insertion can be seen as a two-lane box-ball system, in which a carrier moves particles forward or laterally. Running such two-lane dynamics in parallel on a periodic
lattice gives rise to a two-dimensional generalization of the box-ball system, which we call the skew column RSK dynamics. Equivalently, this is a deterministic dynamics on pairs of skew semistandard Young tableaux $(P_t,Q_t)_{t \in \mathbb{Z}}$. We prove that this dynamics exhibits solitonic behavior and construct an explicit bijection $(P,Q) \leftrightarrow (H_1,H_2,\kappa,\nu)$ that linearizes the time
evolution. The resulting coordinates consist of two horizontally weak tableaux $H_1,H_2$ recording the asymptotic
soliton data, integer riggings $\kappa$, and a weakly decreasing sequence of integers $\nu$. A key feature of the construction is an explicit projection from the skew column RSK dynamics to the classical box-ball system; under this projection, the rigging $\kappa$ is precisely the Kerov–Kirillov–Reshetikhin rigging of the associated box-ball configuration. Our proof uses two commuting affine
crystal structures on pairs of skew tableaux and a novel connectivity
theorem for distinguished subgraphs of tensor products of Kirillov–Reshetikhin
crystals. We also derive Greene-type formulas for the
soliton lengths in terms of last-passage percolation on the associated cylindrical environment. Finally, by taking generating functions in the linearizing coordinates, we obtain bijective proofs of Cauchy and Kawanaka–Littlewood-type identities for transformed
Hall–Littlewood
polynomials.
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All authors Takashi Imamura, Matteo Mucciconi, Tomohiro Sasamoto, Travis Scrimshaw
Materials Science
Hybrid Electronic-Ionic Ferroelectricity in Superlubric van der Waals Heterostructures
Jing Huang, Jun Kang and Daniel Bennett
One strategy to lower the switching barrier in a sliding ferroelectric (sFE) is to insert an incommensurate spacer to reduce sliding friction, creating a superlubric sliding ferroelectric (SL-sFE). However, how polarization survives across the effectively decoupled outer layers remains an open question. We show that SL-sFEs are fundamentally different from conventional sFEs: polarization is not driven by sliding alone, but by an intricate coupling between interlayer sliding and the out-of-plane buckling of the spacer layer. This coupling results in a unique hybrid electronic-ionic polarization arising from asymmetric orbital hybridization. The interplay of these order parameters generates several distinct types of ferroelectric hysteresis, including mixed first- and second-order transitions, multi-step switching, and antiferroelectric-like behavior, establishing SL-sFEs as a distinct class of ferroelectrics.
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Superconductivity
Distinguishing Majorana zero modes from trivial defect states in an iron-based superconductor
Dongfei Wang, Jon Ortuzar, Freek Massee et al. (+5 more)
Majorana zero modes, which obey non-Abelian exchange statistics, are promising candidates for topological
quantum computation due to their robustness against environmental perturbations. The iron-based
superconductor Fe(Te,Se) has been identified as an intrinsic topological
superconductor, possibly hosting Majorana zero modes. In this paper, we report the observation of near-zero-energy localized states at multiple structural defects on the Fe(Te,Se) surface, which could be misidentified as Majorana zero modes without additional verification. By using
spin-polarized scanning tunneling spectroscopy, we demonstrate that the near-zero-energy localized states on step edges and line defects originate from topologically trivial Yu-Shiba-Rusinov states. In addition, zero-energy bound states are also observed for regions without surface defects. A combined spatial and
magnetic field dependent analysis of the
spin-resolved tunneling spectra in these regions reveals that this type of zero-energy states cannot be attributed to the presence of Majorana bound states. These findings emphasize the importance of
spin-dependent studies of low-energy states for pursuing Majorana zero modes.
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All authors Dongfei Wang, Jon Ortuzar, Freek Massee, Ruidan Zhong, Genda Gu, Wende Xiao, Yugui Yao, Roland Wiesendanger
Quantum Gases
Vorticity Induced by Non-frontal Collisions of Quantum Droplets
J. E. Alba-Arroyo, Santiago F. Caballero-Benitez and Rocio Jáuregui
The rotational dynamics induced by the non-frontal binary collisions of
quantum droplets composed of ultracold alkali atoms are analyzed. A theoretical study is presented within the extended Gross-Pitaevskii equation framework, using experimentally feasible conditions. Numerical experiments elucidate a rich landscape of possible topological excitations in the system that are robust towards measurements. The collision of heteronuclear
quantum droplets composed of $^{41}$K and $^{87}$Rb atoms in the incompressible regime gives rise to dynamical instabilities that spontaneously generate topological defects:
vortex rings, dislocation lines, and
vortices in one species. Their presence depends on the Weber number and the impact parameter. An experimental proposal for
vortex detection in both real and
Fourier space using interaction ramps is described.
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High Energy Astrophysical Phenomena
Effects of Rotation on the Gravitational Momentum Transfer in Neutron-Star Kicks and Implications for Spin-Kick Alignment
Yiming Lu and Eric G. Blackman
Neutron stars are often born with large
recoil velocities, or natal kicks, whose physical origin remains an open question in core-collapse
supernova theory. Observations suggest that the
spin-kick angle distribution is not isotropic but skewed toward a
spin-kick vector
alignment. One possible kick mechanism is the gravitational tug-boat effect, in which anisotropic ejecta gravitationally accelerate the proto-
neutron star over a timescale of seconds after shock revival, although the long-term importance of this effect relative to other hydrodynamic forces remains debated. Previous derivations of the tug-boat mechanism do not include the effect of initial
stellar rotation. Here we derive a minimalist extension to assess how rotation of the expanding asymmetric mass distribution influences
spin-kick
alignment of gravitational momentum transfer. We show that the
spin-kick angle is determined by the product of two factors, one that depends on the ratio of shock expansion time to the rotation period and the other which depends on the orientation of the asymmetric mass distribution with respect to the
spin-axis. For fast enough rotation, the first factor amounts to axially averaging out non-axisymmetry thereby suppressing the perpendicular tug and leaving only a
spin-aligned force. However, the rotation speed required for this effect would be unrealistically large unless
magnetic fields could transport angular momentum from the core to the
outflow efficiently.
Spin-kick
alignment by the tug-boat mechanism would otherwise require the second factor, namely a preferentially
spin-aligned mass flux asymmetry. The rotational-averaging framework developed here suggests that, in general, for any kick mechanism that is not sourced by rotation, including rotation will have some tendency to
spin-align the kick, but reduce the kick magnitude.
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Quantum Physics
Impact of Network Constraints on Fault-Tolerant Distributed Quantum Computing
Eneet Kaur, Shahrooz Pouryousef, Nitish Kumar Chandra et al. (+4 more)
As we move towards scalable and modular
quantum computing,
quantum data centres become imperative. Existing analyses typically treat network constraints in isolation or through simplified models, leaving the interplay between error correction operations and communication resources underexplored. In this work, we present an end-to-end simulation framework that jointly models surface-code operations, internal QPU connectivity, and realistic network constraints including finite
entanglement generation rates, limited communication
qubits, and bandwidth contention, producing execution latency, from which logical error rate estimates are obtained. The framework is modular by design, allowing individual components such as routing heuristics, scheduling policies, and network
topologies to be independently replaced. Numerical evaluation reveals distinct operating regimes in which the optimal resource allocation and code distance selection shift depending on the network characteristics. These results point to tradeoffs in the design of distributed
quantum computing architectures that are not visible when computation and communication are modeled separately.
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All authors Eneet Kaur, Shahrooz Pouryousef, Nitish Kumar Chandra, Hassan Shapourian, Jiapeng Zhao, Ramana Kompella, Reza Nejabati
High Energy Astrophysical Phenomena
Revisiting Disk Winds in Active Galactic Nuclei as an Origin of Cosmic Gamma-ray and Neutrino Backgrounds
Nobuyuki Sakai, Yoshiyuki Inoue and Ellis R. Owen
The origin of the
cosmic neutrino background (CNB) and the
cosmic gamma-ray background (CGB) remains uncertain.
Accretion disk winds driven by active
galactic nuclei (AGNs) have been proposed as possible contributors, but their predicted background levels depend sensitively on poorly constrained wind energetics and ambient densities. We revisit the AGN disk-wind scenario by constructing a lepto-hadronic wind model calibrated with
radio and GeV gamma-ray data of nearby
Fermi-LAT-detected Seyfert
galaxies. In our framework,
cosmic rays accelerated both at wind-driven forward and reverse shocks produce synchrotron, external-Compton, and hadronic emission. We also incorporate recent XRISM constraints on wind parameters. Applying our calibrated lepto-hadronic models to an AGN population synthesis model, we find that disk winds contribute at most $\lesssim 5\%$ of the CGB above 10 GeV and $\lesssim 10\%$ of the CNB around 100 TeV, suggesting that they are unlikely to dominate both backgrounds. Finally, we identify nearby Seyfert
galaxies hosting ultrafast
outflows as promising targets for future TeV gamma-ray and TeV$-$PeV
neutrino observations, which would offer firm tests of the disk-wind scenario.
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High Energy Physics (Phenomenology)
Fourier-Preconditioned Path Deformations for Multi-Field Vacuum Tunnelling
Suriyah R. Kannagi, Aadarsh Singh and Sudhir K Vempati
We present an endpoint-safe
Fourier method for multi-field
vacuum tunnelling. The field-space tunnelling path is written as a straight-line interpolation between the false and true
vacua, plus sine-mode deformations that vanish at the endpoints. This gives a finite-dimensional path optimisation problem, which we implement using automatic differentiation in the JAX numerical framework. The method is studied both as a standalone variational ansatz for curved tunnelling paths and as a preconditioner for existing bounce solvers. On the OptiBounce
benchmark potential for $N_\phi=3,\ldots,20$ and on a nested random-coefficient potential family up to $N_\phi=50$, the
Fourier result agrees with FindBounce, OptiBounce, and CosmoTransitions at the sub-percent level in the regular
benchmark cases, while requiring only a modest number of modes. We also compare several endpoint-safe basis families and find that
Fourier sine modes provide a robust default for smooth tunnelling paths. When used as an initialiser, the
Fourier path supplies useful
geometric information to existing solvers before the final bounce calculation is carried out. In the CosmoTransitions tests, this reduces the number of steps in subsequent path deformation, while in the FindBounce point-injection tests, it gives large runtime improvements in the high-dimensional cases up to 90 $\%$. These results suggest that endpoint-safe
Fourier paths provide a useful bridge between simple analytic path ansätze and fully numerical multi-field bounce
algorithms.
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Fluid Dynamics
Diapycnal material transport driven by submesoscale frontogenesis
Tong Bo, James C. McWilliams and Marcelo Chamecki
Submesoscale fronts, occurring at intermediate scales between mesoscale eddies and boundary layer
turbulence, play a crucial role in driving vertical transport from the ocean surface into the interior. Their dynamics involve complex interactions between submesoscale currents and
turbulence. However, the mechanisms by which these multiscale processes combine to transport tracers such as pollutants or nutrients remain less well understood. This study uses large-eddy simulation to investigate passive tracer transport associated with submesoscale fronts. Intense
turbulence develops during frontogenesis, leading to strong diapycnal tracer transport into the ocean interior. While part of this transport arises from the direct turbulent flux, represented by the covariance between turbulent velocity and tracer concentration fluctuations, a substantial portion is due to an advective diapycnal flux driven by the mean diapycnal velocity. The mean diapycnal velocity results from the evolving secondary circulation in the presence of turbulent density mixing. These findings reveal an underexplored diapycnal transport pathway in submesoscale frontal zones, with implications for improved representation of vertical exchange in ocean models.
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Materials Science
Lifetime Sample Tracking (LiST): A Data Platform for Materials Science
Anthony Richardella, Isaiah A Moses, Konrad Hilse et al. (+9 more)
The 2D
Crystal Consortium Materials Innovation Platform (2DCC-MIP) is an NSF supported national user facility focused on advancing the synthesis of 2D materials, monolayers, surfaces, and interfaces. The need for the facility to organize and share data with users led to the development of an internal data management and analysis engine, the Lifetime Sample Tracking platform (LiST). This infrastructure allows the automated capture, curation, analysis and dissemination of data ranging from experimental materials synthesis parameters and characterization, to theoretical first-principles and ReaxFF molecular dynamics modeling1. The system currently hosts synthesis and property data (accessible via a REST API) on approximately twenty thousand samples produced by the 2DCC grown using a variety of techniques from bulk
crystal growth to metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE), among others. Data used in publications can easily be grouped by the system into data packages that are given digital object identifiers (DOIs) for inclusion with each publication. The LiST platform is now being used by groups outside of the 2DCC as a solution for data curation in materials science. Data management tools such as LiST support the materials development process by allowing a closed loop iteration between synthesis, characterization, theory, and targeted materials design. This also enables machine learning (ML) research, artificial intelligence (AI) analysis, and the potential for autonomous synthesis in the future.
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All authors Anthony Richardella, Isaiah A Moses, Konrad Hilse, Frank Santaguida, Kevin Dressler, Ric Wilburn, Saiyyam Kochar, Wesley F. Reinhart, Adri C. T. van Duin, Nitin Samarth, Vincent H. Crespi, Joan M. Redwing
Computational Physics · Cross-listed from cs.LG
Operator Boosting Produces Pareto-Efficient PDE Surrogates
Lennon J. Shikhman
Neural operators are widely used as surrogate solution maps for partial differential equations (PDEs), but full-size models can be costly to store, deploy, and evaluate in many-query scientific workflows. This work introduces Operator Boosting, a stagewise residual-learning framework for constructing compact neural-operator surrogates directly, rather than training a large model and compressing it afterward. Starting from the empirical mean predictor in normalized output coordinates, the method trains a sequence of tiny same-family neural operators on residual fields and incorporates each correction through validation-selected shrinkage. We instantiate the framework with
Fourier neural operators (FNOs), DeepONets, and convolutional neural operators (CNOs), and compare boosted tiny stacks against full-size monolithic baselines across one-, two-, and three-dimensional PDE
benchmarks from PDEBench, APEBench, and The Well. Across 30
dataset-architecture pairs, 21 show positive mean accuracy gains and 17 have positive confidence intervals, while all boosted stacks reduce trainable parameter count by approximately 72-95%. Best-model comparisons show empirical Pareto improvements on 7 of 10 completed PDE
benchmarks, including two-dimensional Navier-Stokes, shallow-water dynamics, Darcy flow, one-dimensional transport and reaction systems, and three-dimensional compressible Navier-Stokes. These results show that Operator Boosting often improves the empirical accuracy-parameter Pareto frontier of neural PDE surrogates, while also exposing PDE- and architecture-dependent regimes where residual boosting fails to offset compression.
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Fluid Dynamics
Curvilinear Moving Overset Method for High-order Non-dissipative Schemes
Minhazul Islam and Nek Sharan
This paper presents a non-dissipative, high-order, moving overset method for curvilinear grids to simulate unsteady compressible flows in complex geometries with moving components. Centered finite-difference schemes that are up to sixth-order accurate in the interior are used with a weak moving overset interface treatment. The novel aspects of the proposed approach compared to conventional overset methods are: (i) instead of overwriting all conservative or primitive variables at the interface (or fringe) points with the interpolated values, a characteristic decomposition is performed and only the incoming characteristic variables are imposed for inviscid flows, consistent with the
hyperbolic character of the Euler equations; for viscous flows, the viscous fluxes are imposed in addition to the incoming characteristics variables, (ii) instead of using multiple layers of fringe points at the interface, the proposed approach ensures high-order accuracy and stability with a single layer, thus minimizing the parallel communication costs at each timestep, and (iii) the proposed approach ensures long time stability with non-dissipative schemes without introducing artificial dissipation explicitly (using numerical filters) or implicitly (using upwind schemes). The stability is demonstrated by an
eigenvalue analysis of the time-dependent (semi-discrete) system
matrix for moving grids, proving the
eigenvalue spectra remains confined to the left half of the complex plane with grid motion. The proposed approach is validated over a range of canonical and practical unsteady flow problems involving moving grids: 1-D scalar advection, 2-D isentropic
vortex convection, flow past rotating 2-D circular cylinder, pitching 2-D and 3-D airfoil/wing flow, and flow past 2-D and 3-D oscillating circular cylinder, demonstrating high-order accuracy and long time stability for inviscid/viscous flows.
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Materials Science · Cross-listed from cs.LG
Toward Controllable Catalyst Inverse Design via Large-Scale Autoregressive Pretraining
Dong Hyeon Mok, Jonggeol Na and Seoin Back
Inverse design of heterogeneous catalysts remains challenging because catalyst surfaces exhibit substantial structural complexity with coupled surface-adsorbate interactions across a vast chemical space that is difficult to explore efficiently through conventional screening alone. Although machine learning-based high-throughput screening has accelerated catalyst discovery, its efficiency inevitably declines as the search space grows, motivating the development of generative models that can directly construct catalysts with target properties. Here, we present a conditional catalyst generative model based on the Generative Pretrained
Transformer architecture with a numerical
embedding layer that enables the generation of catalyst structures conditioned on both categorical and continuous properties within a single autoregressive framework. The model was pretrained on 133 million catalyst structures and subsequently fine-tuned on approximately 460,000 optimized structures with associated categorical properties and binding energies for conditional generation. The resulting model achieved 98% structural validity, 95% optimization validity, and high categorical condition fidelity, with a 93 % joint match rate for adsorbate type and composition. For binding energy conditioning, the match rate of approximately 20% represents a four-fold improvement over the baseline training distribution, and the generated distributions shift systematically toward the target values, enabling a 1.5 to 4-fold improvement in screening efficiency for reaction-targeted catalyst discovery without additional fine-tuning. These results show that large-scale autoregressive pre-training, combined with explicit property conditioning, provides a practical route toward controllable catalyst generation and accelerated catalysts discovery.
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High Energy Astrophysical Phenomena
GRB 250424A: A Case Study of Energy Injection with Multiwavelength Observations
Yifang Liang, Yun Wang, WeiKang Zheng et al. (+61 more)
We present a comprehensive multiwavelength analysis of the long-duration gamma-ray burst (GRB) 250424A. Our
dataset spans from the
prompt gamma-ray emission to late-time optical monitoring, including spectra obtained with the Keck 10\,m
telescope. We find that the afterglow light curves display a prominent, simultaneous shallow decay phase in both X-ray and optical bands, followed by an achromatic transition to a standard decay regime. The broadband spectral energy distributions are well-modeled by a single power-law function, indicating a common synchrotron origin for the emission across frequencies. We interpret the afterglow
evolution within the framework of a relativistic forward shock refreshed by continuous energy injection. This scenario successfully reproduces the observed temporal and spectral behavior, yielding an isotropic equivalent kinetic energy of $E_{\rm K,iso} \approx 5.5 \times 10^{52}$ erg and an injection index of $q\approx 0.34$ in a constant-density circumburst environment. The shallow decay phase is consistent with sustained energy injection lasting $\sim$ 9 ks. Despite the relatively low
redshift, late-time optical observations reveal no distinct
supernova component; however, our derived upper limits do not strictly rule out the presence of a typical GRB-associated
supernova.
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All authors Yifang Liang, Yun Wang, WeiKang Zheng, Priyadarshini Gokuldass, Huali Li, Chenwei Wang, Riccardo Brivio, Donovan Schlekat, Alexei V. Filippenko, Pillas Marion, Dalya Akl, Sarah Antier, Manasanun Tanasan, Kanthanakorn Noysena, Di Xiao, Jie An, Thomas G. Brink, Krittapas Chanchaiworawit, Dylan A. Dutton, Matteo Ferro, Michael Freeberg, Ren Jia, Alain Klotz, Ye Li, Xing Liu, Dan Reichart, Antonio C. Rodriguez, Wenjun Tan, Samaporn Tinyanont, Jing Wang, Zi-Qi Wang, Jianyan Wei, Samuel E. Whitebook, Xuefeng Wu, Dong Xu, Yi Yang, Jinpeng Zhang, Wenlong Zhang, Hao Zhou, Valerio D'Elia, Massimiliano De Pasquale, Dino Fugazza, Luciano Nicastro, Damien Turpin, Roger Hellot, Frederic Dux, Xiangyu Wang, Frederic Daigne, Yongfeng Huang, HongBo Cai, Alexis Coleiro, Bertrand Cordier, Stefano Crepaldi, YongWei Dong, Olivier Godet, XuHui Han, Frederic Piron, YuLei Qiu, Stephane Schanne, Chao Wu, LiPing Xin, Yang Xu, Shuangnan Zhang, ShiJie Zheng
Quantum Physics
Broadband High-Level Squeezed Light using Waveguide Optical Parametric Amplifiers with External Dispersion Compensation
Takumi Suzuki, Shotaro Oki, Kazuki Hirota et al. (+8 more)
We demonstrate broadband phase-sensitive amplification (PSA) measurement of squeezed light generated by a waveguide optical parametric amplifier (OPA) with external dispersion compensation. In broadband systems, group velocity dispersion (GVD) induces a frequency-dependent rotation of the squeezing axis, which limits the observable bandwidth in PSA measurements. While dispersion compensation between two OPAs has been demonstrated previously, we show that the quantity to be compensated is not the material group-delay dispersion $D$ itself but a gain-dependent effective value $D\tanh r/(2r)$, where $r$ is the squeezing parameter, and realize the compensation with free-space fused-silica plates whose insertion loss is $0.4\%$. As a result, we observe a maximum squeezing of $5.9\pm0.2$~dB near the carrier frequency and more than 5~dB of squeezing up to a frequency offset of $5.9\pm0.1$ THz from the carrier. Furthermore, squeezing below the shot-noise level is confirmed up to a frequency offset of $6.9\pm0.1$ THz from the carrier, corresponding to the accessible phase-matching bandwidth of the waveguide OPA. Our results establish a practical method for broadband characterization of squeezed light and provide a key step toward ultrafast continuous-variable
quantum information processing.
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All authors Takumi Suzuki, Shotaro Oki, Kazuki Hirota, Takaya Hoshi, Ryuhoh Ide, Takahiro Kashiwazaki, Taichi Yamashima, Asuka Inoue, Takeshi Umeki, Mamoru Endo, Akira Furusawa
Optics
Bistable topological edge states in polariton microcavities with unpaired Dirac cones
Zhuo Zhang, Yaroslav V. Kartashov, Yongdong Li et al. (+3 more)
Among the most intriguing properties of honeycomb
lattices is the presence of Dirac points that typically emerge in pairs, which can be destroyed by physical effects breaking certain
symmetries of the system and leading to nontrivial band
topology. We propose a nonlinear microcavity system supporting condensate of
exciton-polaritons, where simultaneous breakup of inversion and time-reversal
symmetries results in unusual spectrum with unpaired Dirac cones, profoundly affecting the properties of unidirectional edge states. Realized as an array of microcavity pillars, the inversion
symmetry is broken by fission of pillar belonging to one of sublattices of honeycomb array into three pillars, while time-reversal
symmetry is broken due to interplay of Zeeman splitting in the external
magnetic field and
spin-orbit coupling. Despite the absence of complete spectral gap, unidirectional edge states may still emerge that can circumvent array corners. Resonant optical pumping leads to reach bistability effects and allow selective excitation of the edge states. We obtain first example of stable localized dissipative edge
soliton that circulates along the periphery of
insulator over indefinitely long times without radiation. Our results suggest a new platform for nonlinear topological photonics and reveal nontrivial interplay between unpaired Dirac cones and nonlinear effects.
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All authors Zhuo Zhang, Yaroslav V. Kartashov, Yongdong Li, Zhen-Nan Tian, Qi-Dai Chen, Yiqi Zhang