Instrumentation and Methods for Astrophysics
Reinforcement learning for post-coronagraphic wavefront control
Manuela Castañeda-Medina, Yann Gutierrez, Johan Mazoyer et al. (+3 more)
Direct imaging of
exoplanets is limited by the extreme contrast between the
star and the
planets, which is mitigated using a coronagraph. However, optical aberrations cause starlight leakage through the coronagraph, producing speckles that obscure the planetary signal. Achieving the required contrast levels demands wavefront control with subnanometric precision. Deep reinforcement learning offers a promising alternative to traditional focal-plane wavefront control techniques by enabling adaptive correction strategies learned directly from interaction with the system. In this work, we present a fully data-driven method for post-coronagraphic aberration correction in a simulated high-contrast imaging testbed. The
agent controls a deformable mirror using observations consisting of focal-plane measurements (images) and physics-informed wavefront sensing information derived from these images. We evaluate different observation representations and control strategies, and the method is validated on simplified simulations of a high-contrast imaging testbed, where it successfully creates dark holes, i.e., regions of the focal plane in which residual starlight is strongly suppressed, while approaching the performance of conventional wavefront control methods.
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All authors Manuela Castañeda-Medina, Yann Gutierrez, Johan Mazoyer, Baptiste Abeloos, Laurent Mugnier, Olivier Herscovici-Schiller
Mathematical Physics · Cross-listed from math.OA
Equivalence of states and bimodule quantum channels
Linzhe Huang, Chunlan Jiang, Zhengwei Liu et al. (+1 more)
We study the action of
quantum channels on states on a von Neumann
algebra $\mathcal{M}$ with conserved quantities encoded by a subalgebra $\mathcal{N}$. We define a phase as an equivalence class of normal states on $\mathcal{M}$ under the action of
quantum channels preserving $\mathcal{N}$. First, we establish a relative quasi-entropic characterization of phase equivalence using the Petz recovery map. We further introduce the operator
algebra (OA)
symmetry of a state and define an equivalence relation between OA
symmetries via bishifts of biprojections. When $\mathcal{N}\subseteq\mathcal{M}$ is an irreducible finite-index subfactor of type II$_1$, we prove that phase equivalence implies OA
symmetry equivalence. Consequently, OA
symmetry breaking provides a sufficient mechanism for detecting phase transitions. Furthermore, combining finite-index subfactor theory with
quantum Fourier analysis, we prove that the cardinality of each phase is finite and obtain an explicit upper bound depending only on the Jones index.
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All authors Linzhe Huang, Chunlan Jiang, Zhengwei Liu, Jinsong Wu
Medical Physics
Retinal hazards and glare from space mirrors
Salvador Bará
Projects of orbital mirrors reflecting sunlight towards Earth raise reasonable concerns regarding photochemical and thermal retinal hazards and detrimental effects on visual performance (disability glare). This paper addresses these issues based on some current eye safety and glare standards. Telescopic observations of single mirrors appear to pose a significant risk of photochemical retinal hazard. The risk is higher for vulnerable populations. Unaided eye viewing of a mirror keeps the retinal risks low, both photochemical and thermal; however, disability glare may be unacceptably high, affecting awareness and response in critical visual operations. The simultaneous presence of several mirrors in the visual field of the observer, seen with the unaided eye or through optical instruments, will significantly increase all types of hazards. The kind and severity of their combined effects will depend on the angular distance between them. Additional information is needed to evaluate the effects of the transient flashes of light during mirror slewing operations.
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Quantum Physics
Stabilizer-Public-Key Authentication: Long Stabilizer Public Keys Resist Finite-Copy Forgery Attacks
Masahito Hayashi, Jingtian Zhao and Baichu Yu
We propose an information-theoretic authentication protocol based on a finite supply of long quadratic-stabilizer public-key states over an odd-
prime field, where the effective key length after one signature exposure is the residual dimension $r=n-\ell$. A computationally unbounded adversary observes one valid classical signature and may jointly process $N$ public-key copies, while verification uses one additional independent copy. We show that, conditioned on the exposed signature, the security problem reduces to a partial-prediction game for a uniform stabilizer ensemble on these $r$ residual qudits, with a partial query along $d=\operatorname{rank}(Y-Y')$ directions, where $Y$ and $Y'$ denote the honestly signed and target-forged messages, respectively. Surprisingly, although the target requires only partial information, there is no first-order reduction in the required copy rate when $d/r\to\beta\in(0,1]$. The optimal average forgery probability for the specified target tends to zero for $N/r\to\alpha<1$ and to one for $\alpha>1$, revealing a sharp threshold at $\alpha=1$. Thus, long stabilizer public keys resist finite-copy forgery attacks under a single-signature-exposure model whenever the
adversarial copy rate remains below one.
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Astrophysics of Galaxies
The extreme Disturbed Galaxy Cluster Sample (eDGeS): Spectroscopy and Dynamical Analysis of the eROSITA-Selected Merging Galaxy Cluster Candidate 1eRASS J025859.4-193727
Anish S. Aradhey, Eleazar R. Carrasco, Alfredo Zenteno et al. (+7 more)
Addressing open questions such as the effect of
galaxy cluster mergers on the
evolution of
galaxies and the self-interaction cross-section of dark matter requires the construction of a large, diverse sample of disturbed
galaxy clusters. One contribution to such a sample is the extreme Disturbed
Galaxy Cluster Sample (eDGeS), an ongoing spectroscopic study of massive disturbed and merging
galaxy clusters selected from complementary surveys. Here, we present our first results from the eROSITA-selected subsample (eDGeS-eROSITA): a dynamical state analysis for the merging cluster candidate 1eRASS J025859.4-193727. We present the first spectroscopic
redshift measurements for 76
galaxies in the direction of the cluster, confirming 51 as cluster members. The cluster displays a line-of-sight velocity dispersion of $\sigma_{\rm{cl}}=808^{+59}_{-66}~\rm{km~s^{-1}}$ and a dynamical mass of $M_{200}=4.47^{+0.94}_{-0.93} \times 10^{14}~M_{\rm{Sun}}$. While the cluster shows no evidence for substructure along the line of sight, the projected distribution of member
galaxies reveals three subclusters, only one of which appears associated with the cluster's X-ray contours. Phase-space analysis reveals a large fraction of recently infallen member
galaxies. Together, this evidence suggests a cluster merger along the plane of the sky. Assuming that the two most massive subclusters are on outgoing (incoming) trajectories after their first pericentric passage, a two-body Monte Carlo model predicts that the two subclusters collided $0.50^{+0.20}_{-0.22}~\rm{Gyr}$ ($1.24^{+0.96}_{-0.38}~\rm{Gyr}$) ago.
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All authors Anish S. Aradhey, Eleazar R. Carrasco, Alfredo Zenteno, Rogério Monteiro-Oliveira, Facundo A. Gómez, Konstantina Boutsia, Esra Bulbul, Guillermo Damke, Amelia Ramirez, Hector Cuevas
Quantum Gases
Radial dam breaks in a two-dimensional droplet bearing environment
F. Bristy, S. Chandramouli, G. A. Bougas et al. (+3 more)
The controlled dynamical generation of radial dam break flows (DBFs) is demonstrated in two-dimensional droplet environments. These ultracold mixtures feature competing mean-field and
quantum fluctuation effects and are initialized on a disk-shaped uniform density. Depending on the value of the latter, reflecting also the dominance of attractive or repulsive interactions, three dynamical response regimes are identified. At small densities a moving wavetrain of bright ring
solitons is observed (dubbed ring DBF), at intermediate densities a ring kink-dispersive shock wave, while at large densities the flows encompass composite ring kink-rarefaction waves moving towards the center. The emergence of these patterns, whose formation would be prohibited in two-dimensional Kerr media due to wave-collapse, is rooted in the competition between attraction and repulsion inherent to droplet environments, modeled by the extended Gross-Pitaevskii equation. The characterization of the ensuing nonlinear waveforms is further corroborated by reduced models based on the cubic-quintic nonlinear Schrödinger equation. The different wave patterns emanating from dam break flows can be experimentally realized using current state-of-the-art ultracold atom experiments.
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All authors F. Bristy, S. Chandramouli, G. A. Bougas, G. C. Katsimiga, P. G. Kevrekidis, S. I. Mistakidis
Fluid Dynamics
Wake interactions drive synchronized vortex merging in a hovering quadcopter
Elias S. Pratschke, Claus C. Wolf, Daniel Schanz et al. (+2 more)
The most energetic coherent structure of a hovering full-scale quadcopter is associated with a self-organizing process in which the individual rotor
vortices synchronize their frequencies while undergoing merging events, yielding a globally correlated structure. We identify and characterize this phenomenon by applying spectral modal and conditional analyses to assimilated three-dimensional velocity data acquired via Shake-The-Box Lagrangian particle tracking. The
dataset captures a high-Re, turbulent flow further complicated by time-varying rotor speeds stemming from active flight control, low-frequency vehicle drift, finite spatio-temporal resolution, and measurement uncertainty. Most coherent structures recover established single-rotor features such as tip
vortices and their subharmonic pairing. The globally synchronized
vortex merging manifests as a spectral peak at an incommensurate frequency below the rotor band, which cannot be explained by single-rotor aerodynamics, subharmonic instabilities, or band-to-band triadic interactions. Instead, conditional averaging provides evidence of the aforementioned intermittent, distinctly non-subharmonic
vortex-merging process involving all four rotor wakes. Establishing whether or not this phenomenon is observed across different flight conditions and configurations remains speculative; however, the consistent characterization of the globally synchronized
vortex merging using complementary frequency- and time-domain analyses despite experimental complexities, in particular rotor speed variations, demonstrates its robustness.
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All authors Elias S. Pratschke, Claus C. Wolf, Daniel Schanz, Andreas Schröder, Oliver T. Schmidt
Mathematical Physics
Eberlein convolution as an inner product and quantitative Bombieri–Taylor results
Daniel Lenz and Nicolae Strungaru
We present a simple argument providing a very general Bombieri–Taylor-type result to compute Bragg peaks in diffraction theory as limits. At its abstract core the argument relies on considering the Eberlein convolution as an inner product. This inner product gives an abstract version of a Cauchy–Schwarz type inequality which implies the Bombieri–Taylor-type result as well as generalizations.
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General Relativity and Quantum Cosmology
Relativistic Stellar Oscillations from Ultralight Dark Matter
Shanae Oishi, Christopher Reyes and Jeremy Sakstein
Ultra-light dark matter, composed of
bosons behaving as classical waves, can resonantly excite
stellar oscillations. In this work, we investigate this phenomenon in relativistic
stars, showing that $\ell=0$ fluid modes can be excited. We derive a framework for calculating the mode amplitude and apply it to
neutron stars to predict the associated surface temperature fluctuations; the resulting signal lies beyond current observational sensitivities. We discuss prospects for extending this approach to other compact objects.
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Mathematical Physics
Boundary parity in the mirror model on the Manhattan lattice
Jian Gu and Qin Hao
We study a finite-domain event for the mirror model on the Manhattan
lattice: every boundary-to-boundary trajectory crosses a marked connector an even number of times, while internal cycles are unrestricted. Our main
theorem gives a finite-scale confinement criterion: if this event's probability reaches a universal threshold in one even two-square rectangle, then almost surely every trajectory in the plane is periodic. We construct an exactly normalized three-color tensor representation and prove deterministic bounds for approximate contractions using the signed partial-permutation structure of directed continuations. These tools turn numerical evaluations into rigorous finite-volume statements. At mirror density \(p=2/5\), we prove that the boundary-parity probability is nonmonotone in the rectangle width, with a decrease followed by a certified increase. These values remain below the sufficient confinement threshold and do not resolve planar localization at this density. Further experiments track how the measured finite-size minimum varies with density, compare matching-based and entrywise error bounds, and exhibit endpoint-sensitive and cooperative responses to local mirror changes.
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Quantum Physics
Engineering and Probing a One-Dimensional Dipolar Spin Ensemble in Diamond
Lingjie Chen, Shreyas Parthasarathy, Simon A. Meynell et al. (+11 more)
Dimensionality plays a central role in determining the collective behavior of interacting
quantum systems. Engineering strongly interacting ensembles of solid-state
spin defects in reduced dimensions remains a significant challenge at the interface between the applied and fundamental sciences. Here, we create and characterize a positionally disordered, quasi-one-dimensional
spin chain in diamond, consisting of optically dark substitutional nitrogen defects (P1 centers) and optically addressable probe nitrogen-vacancy (NV) centers. Our approach exploits the preferential incorporation of nitrogen along step bunches formed during chemical vapor deposition to achieve both lateral and vertical confinement. Combining spatially resolved materials characterization with nanoscale
quantum sensing, we establish the one-dimensional character of the optically dark, unpolarized P1
spin ensemble. We then use correlation spectroscopy to probe local
spin autocorrelations and investigate infinite-temperature dipolar
spin transport. Our results establish a materials-based route for engineering low-dimensional
quantum spin systems.
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All authors Lingjie Chen, Shreyas Parthasarathy, Simon A. Meynell, Lillian B. Hughes Wyatt, Eveline Postelnicu, Haopu Yang, Zilin Wang, Weijie Wu, Winston V. Peloso, Casey K. Kim, Chris R. Laumann, Kunal Mukherjee, Norman Y. Yao, Ania C. Bleszynski Jayich
Applied Physics
Giant Resonant Reflection Gain from Injection-Induced Quenching in a Tunnel Diode
Darmindra Arumugam, Jack Bush and Brook Feyissa
Negative-resistance microwave oscillators can simultaneously sustain autonomous oscillations and coherently scatter electromagnetic waves, enabling active reflection beyond conventional linear amplification. Here we demonstrate
giant resonant reflection gain from synchronization-induced phase localization in a self-sustained tunnel diode oscillator operating near 2.96 GHz. Weak resonant RF injection drives a transition from a broadband free running state to a phase localized narrowband reflected carrier. The resulting reflected enhancement reaches 83.1dB relative to the injected signal and is accompanied by greater than order of magnitude linewidth collapse, nonlinear injection pulling, and a synchronization bandwidth of 15.84 kHz. Time resolved spectrograms directly resolve injection locking and frequency entrainment, while noisy Stuart Landau simulations reproduce the observed spectral concentration and detuning dependent gain roll off near the
Hopf instability. Artificially increasing phase
diffusion with broadband bias noise suppresses the reflected enhancement, confirming synchronization-induced quenching of phase fluctuations as the origin of the
giant coherent reflection gain.
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Superconductivity
Pairing symmetry and superconductivity from long-range Coulomb interactions in the extended t-t'-t”-Jz model for cuprates
U.A. Diaz-Reynoso and F. Mireles
We investigate the pairing
symmetry of the ground-state phase diagram of an extended two-dimensional $t$-$t'$-$t''$-$J_z$ model, in which the first-, second-, and third-nearest neighbor electron hopping terms ($t,t'$ and $t''$) and an anisotropic Ising-like
antiferromagnetic interaction $J_z$ are treated on the same framework. We find that the dominant pairing
symmetry depends sensitively on the sign and magnitude of the hopping parameters $t'$ and $t''$, showing pure $p$-wave, pure $d$-wave, or coexisting pairing channels, highlighting the decisive role of these terms. We further explore the role of the long-range and short-range repulsive interactions in the formation of pairs and analyze the specific case of hole-doped cuprates. Our results indicate that repulsive interactions favors hole pair escaping of the stripe domains. Furthermore, pairing correlation calculations strongly suggest that repulsive Coulomb interactions drive reentrant superconducting behavior at experimentally observed underdoped regime ($\delta\approx0.07$ to $0.15$), as in Neodymium-based cuprates.
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Materials Science
ALIGNN 2.0: A Unified Line-Graph Neural Network Framework for Materials Screening, Force Fields, Inverse Design, Spectroscopy, and Microscopy
Jaehyung Lee, Charles Rhys Campbell, Akshaya Ajith et al. (+3 more)
Graph neural networks are central to materials property prediction and machine-learning interatomic potentials, yet their reliance on specialized graph libraries hampers portability and reproducibility, and property and force-field models have historically required separate graph pipelines. We present ALIGNN 2.0, a dependency-free, pure-PyTorch reimplementation of the Atomistic Line Graph Neural Network, with the line graph and its batching built from scratch, running on current-generation accelerators and unifying scalar, spectral, tensorial, per-atom, and force-field prediction behind a single graph, a combination that to our knowledge no existing framework provides. Comparing radius and k-nearest-neighbor (kNN) graphs, the wider kNN graph is more accurate for properties while the smoothly varying radius graph is required for energy-conserving molecular dynamics. On the JARVIS-Leaderboard, ALIGNN 2.0 leads on 26 of 30 single-property
benchmarks against the original ALIGNN, with large gains for piezoelectric and dielectric maxima, exfoliation energy,
moduli, and superconducting Tc. The LAMMPS- and OpenMM-compatible ALIGNN-FF matches leading universal potentials on the Matbench-Discovery and CHIPS-FF
benchmarks at a small fraction of their parameters while scaling to hundred-thousand-atom
cells. We further use ALIGNN 2.0 as the denoiser in a conditional
crystal-
diffusion model, where explicit line-graph message passing consistently lowers structural denoising loss. We also show, as work in progress, that an independently diffused, redundant bond-angle state is learnable but does not uniformly improve reconstruction or combine additively with the line graph. Finally, from a single relaxed structure the same framework reconstructs infrared, Raman, optical-dielectric, and
neutron spectra in agreement with experiment and DFT, and drives frozen-
phonon electron-microscopy image simulation.
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All authors Jaehyung Lee, Charles Rhys Campbell, Akshaya Ajith, Sergei V. Kalinin, Christopher Wolverton, Kamal Choudhary
Astrophysics of Galaxies
Honoring Paris Pişmiş' Legacy: Uniform Astrophysical Properties of 14 Understudied Clusters from Gaia DR3
Seliz Koç, Neslihan Alan, Furkan Akbaba et al. (+1 more)
Open clusters are fundamental tracers of the chemical and dynamical
evolution of the
Galactic disc. This study presents a systematic characterisation of 14 understudied open clusters from the Pismis catalogue, selected for a well-defined
stellar sequence in
Gaia DR3 and spanning a wide range of ages and distances. Using high-precision
Gaia DR3 astrometry, we provide a high-fidelity modernisation of these historical discoveries while testing our analytical framework across diverse
stellar populations. Membership probabilities were determined via the unsupervised UPMASK
algorithm using
Gaia DR3 positions, proper motions, and parallaxes. To ensure high sample purity, the member samples entering the isochrone fits were restricted to P >= 0.90, with astrophysical parameters calculated through membership-weighted likelihoods. Fundamental properties – age, distance, reddening, and
metallicity – were derived using a
Bayesian Nested Sampling approach to isochrone fitting, chosen for its robustness against the parameter degeneracies typical of dense
Galactic fields. The 14 systems exhibit a broad range of properties, with ages from approximately 11 Myr to 1.5 Gyr and distances spanning approximately 690 to 5445 pc. These refined, uniform parameters reconcile historical observations with the precision era of modern astrophysics, providing a homogeneous baseline for systems that large-scale automated surveys recover only partially. A direct cross-match against widely used automated catalogues shows that they typically contain only about a third of the members identified here, and substantially less in the most crowded fields, underscoriecific analysis. This workcontributes to a more complete census of the
Galactic disc and sets out a reproducible, per-cluster licable to the manycomparable low-latitude systems still to be characterised.
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All authors Seliz Koç, Neslihan Alan, Furkan Akbaba, Olcay Plevne
Quantum Physics
Efficiently estimating failure rates of fault-tolerant logical non-Clifford blocks
Julio C. Magdalena de la Fuente and Thomas R. Scruby
Useful
quantum computation requires the fault-tolerant implementations of a universal gate set which are generically not efficiently simulable. We devise an algebraic framework that allows for efficient sampling from the measurement distribution of fault-tolerant
circuits that implement diagonal logic gates in the third level of the Clifford hierarchy. Upon successful sampling we also provide sufficient conditions for decoding success. The resulting estimate for the logical failure rate is an overestimate, which becomes more accurate for blocks that are fault tolerant against arbitrary local errors. The non-Clifford simulation overhead is independent of the number of logical
qubits, making the method particularly attractive for large-scale simulations. The framework is based on viewing the non-Clifford gates in the
circuit as a
cohomology invariant of an underlying spacetime fault complex. The method can also be interfaced with Clifford simulators to simulate larger fault-tolerant
circuits and algorithmic subroutines.
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Quantum Physics
Scalable Simulation of Quantum Dynamics on Topological Quantum Hardware
Kritanjan Polley and Mark E. Tuckerman
Quantum computers offer a significant advantage in simulating
quantum systems compared to classical computers for certain problems, although most current applications are limited to calculating static molecular properties using hybrid
quantum-classical hardware. In this work, we establish a framework for the representation of
quantum dynamics in molecular and condensed matter systems, designed for execution on topological
quantum hardware. By leveraging the non-Abelian braiding statistics of Fibonacci and Ising anyons, we utilize the Solovay-Kitaev
algorithm to approximate
unitary propagators for a range of systems. We demonstrate the efficacy of these
algorithms across a hierarchy of complexity, from two-level systems and one dimensional double-well potentials to condensed phase
spin-
boson models, simple molecules, and molecular reaction kinetics. These
algorithms provide a scalable and robust pathway for simulating many-body condensed phase chemical physics on fault-tolerant
quantum devices.
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General Relativity and Quantum Cosmology
Classical Noise in Transient USR Inflation
Harish D. N., Chen-Pin Yeh and Da-Shin Lee
In single-field inflation, linear perturbations originate as
quantum fluctuations and undergo a
quantum-to-classical transition on super-horizon scales as the decaying mode of the comoving
curvature perturbation $\mathcal{R}$ is suppressed. This transition provides a condition for the validity of a classical
stochastic description of $\mathcal{R}$. We characterize classicality through the suppression of the
quantum commutator relative to phase-space variances and the
evolution of the squeezing parameters. In the Starobinsky model, we show that this transition becomes mode-dependent at linear order due to the transient ultra-slow-roll (USR) phase. This is because the decaying mode transiently grows during the USR phase modifying the squeezing dynamics, and shifting the classicalization time depending on when modes exit the horizon relative to the USR phase. We then study the implications of this mode-dependent transition for the
stochastic description of perturbations. Using the Green's function method, we show that the
stochastic spectrum reproduces the power spectrum of the
quantum state initialized in the Bunch-Davies
vacuum, independently of the mode-dependent transition when the gradient term is retained in the Langevin equation, for both white and colored noise coarse-graining. In contrast, ignoring the gradient term in the Langevin equation introduces an explicit dependence on the coarse-graining parameter $\sigma$. Homogeneous matching procedure can be used to set mode-dependent $\sigma(k)$ that reproduces the power spectrum of the
quantum state at the end of inflation. Crucially, however, we show that the matching times precede the classicalization times for modes near the USR transition. Therefore, the transient USR phase in this model leads to a mode-dependent condition for when linear
curvature perturbations can be described as classical
stochastic noise.
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High Energy Astrophysical Phenomena
Lepto-hadronic modeling of blazars associated with well-reconstructed high-energy neutrino events
Leonard Pfeiffer, Margot Boughelilba, Simone Garrappa et al. (+3 more)
The association of active
galactic nuclei (AGN) with high-energy
neutrinos has been studied through population and individual source analyzes, but whether these associations reflect physical processes or chance coincidences remains open. Blazars, AGN with relativistic jets aligned with the line of sight, spatially consistent with IceCube high-energy events, offer a natural framework to address this question. Combining multifrequency observations with physically motivated emission models allows us to assess whether these sources can plausibly account for the detected
neutrinos. We study six blazars with single gamma-ray counterparts to well-reconstructed IceCAT-1 high-energy events, accounting for the improved localization expected from IceCAT-2, and compile their multifrequency spectral energy distributions (SEDs). We model these sources within a lepto-hadronic framework, exploring their parameter space to reproduce the observed emission while favoring solutions that maximize
neutrino production. The SEDs can be reproduced with compact emission regions close to the broad-line region with moderate Doppler factors. The emission is generally leptonic-dominated, with subdominant contributions from hadronic cascades, except for one source where the gamma-rays are hadronic-dominated. For four, the energy density of the relativistic particles is close to equipartition with the
magnetic field. The predicted
neutrino detection rates reach up to $~5x10^{-2}$ per year, mostly compatible with one observed IceCube event under Poisson statistics. While these blazars are unlikely to significantly contribute to the diffuse
neutrino flux, their properties are consistent with being possible counterparts to individual
neutrino events, driven by contributions of external
photon fields to the hadronic interaction rate, even for sources where these fields have previously been considered as non-significant.
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All authors Leonard Pfeiffer, Margot Boughelilba, Simone Garrappa, Sara Buson, Massimiliano Lincetto, Annette Bremer
Superconductivity
Surface-condition-mediated supercooling of the A-B transition in confined superfluid helium-3
Daksh Malhotra, Aymar Muhikira, Alexander J. Shook et al. (+1 more)
Chiral $p$-wave
superconductors and superfluids are central model systems in the search for topological
quantum matter, but in reduced dimensions their properties are inseparable from the boundary conditions imposed by surrounding surfaces. Superfluid $^3$He provides a uniquely clean, well-established
spin-triplet $p$-wave condensate in which these boundary conditions can be engineered directly. Here, we use a fourth-sound Helmholtz resonator to study the A–B phase transition of $^3$He confined to a $1.8\,\mu$m cavity after preplating the internal surfaces with $\sim4$ atomic layers of $^4$He. In contrast to our previous fourth-sound measurements, which showed no resolvable hysteresis in the transition temperature, the preplated device exhibits a clear separation between cooling and warming transition temperatures together with
stochastic run-to-run variations. The hysteresis decreases toward the highest pressures studied, consistent with previous observations of the pressure dependence of $^4$He-mediated quasiparticle boundary scattering. These results demonstrate that surface preparation can qualitatively modify first-order transition kinetics in confined $^3$He, making boundary conditions an experimentally accessible control parameter for metastability and for future studies of reduced-dimension topological superfluid states.
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All authors Daksh Malhotra, Aymar Muhikira, Alexander J. Shook, John P. Davis
Chemical Physics
DFT GGA based datasets for H$_2$O potential energy surfaces, permanent moment and polarizability tensors
Anoop Ajaya Kumar Nair and Elvar Örn Jónsson
We present in this article data on the computed potential energy surface, permanent moment surface (from dipole to hexadecapole) and polarizability surface (from dipole-dipole to quadrupole-quadrupole) for the H$_2$O molecule, calculated at the level of the generalized gradient approximation (GGA) in Kohn-Sham density functional theory (KS-DFT) in the grid-based projector augmented wave code GPAW, using the charge perturbation code C-pol. The GGA-based functionals are PBE, RPBE and BLYP. The monomer surfaces are composed of systematic,
symmetry-reduced deformations of the H$_2$O monomer and comprise 10,000 configurations per functional, with traceless Cartesian tensor moment values reported as data strings in the xyz file format. In addition, we provide cluster
datasets for n-H$_2$O aggregates (n = 2-6), sampled from
liquid-like configurations and computed with the same KS-DFT settings, where each extended xyz file encodes the total interaction energy of the cluster in the comment line. Finally, ab initio molecular dynamics (AIMD) trajectories of periodic
liquid water boxes, containing between 25 to 150 H$_2$O molecules at ambient conditions, are included, furnishing time series of atomic configurations and energies that are consistent with the monomer and cluster data and suitable for validating classical and machine-learned water models.
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Materials Science
The Origin of the Observed Raman Peaks in {\alpha}-MnTe
Nurul Azam, Syed Mohammad Shahed, Liam T. Schmidt et al. (+21 more)
The Raman spectrum of the room-temperature altermagnet $\alpha$-MnTe is reported to contain unassigned peaks at 120(3) cm$^{-1}$ and 140(3) cm$^{-1}$, absent from the predicted
phonon spectrum of the material. This has generated considerable debate within the altermagnet community and necessitates urgent resolution. This work establishes that these peaks, together with the 90(5) cm$^{-1}$ peak that matches a theoretically predicted mode, are all extrinsic, originating from elemental tellurium formed during air exposure of the surface. Raman spectra of MBE-grown thin films show that these peaks closely match those of elemental tellurium, emerge soon after air exposure, and are absent in AlO$_x$-capped films. X-ray photoelectron spectroscopy shows that air exposure breaks Mn–Te bonds and oxidizes Mn within a minute. Cross-sectional scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy reveals that the oxidation leads to Mn out-
diffusion, forming a few-nanometer-thick
oxide layer above a buried, Te-enriched region, likely responsible for the anomalous Raman peaks. Additionally, no sample exhibited the 175 cm$^{-1}$ Raman peak which is commonly attributed to MnTe$_2$. The aggressive surface oxidation and associated elemental Te formation in MnTe have important implications for any surface-sensitive and optical characterization of MnTe (and other similar Te-containing materials) involving even the briefest air exposure.
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All authors Nurul Azam, Syed Mohammad Shahed, Liam T. Schmidt, Sara Bey, Oksana Yastrubchak, Maria F. Munoz, Riccardo Torsi, Thi Hai Yen Pham, Dushyanthini Balasundaram, Resham Babu Regami, Wentao Liang, Imrankhan Mulani, Matthew Matzelle, Vineet Kumar Sharma, Sougata Mardanya, Sugata Chowdhury, Nirmal Ghimire, Patrick M. Vora, Angela R. Hight Walker, Xinyu Liu, Badih A. Assaf, Arun Bansil, Alberto De la Torre, Swastik Kar
General Relativity and Quantum Cosmology
James Buda, Andrew Laeuger and Yanbei Chen
Gravitational-wave (GW)
memory is a permanent change in spacetime geometry induced by a burst of gravitational waves. It is theoretically interesting for its connection to asymptotic
symmetries, but has not yet been observed. The upcoming
Laser Interferometer Space
Antenna (LISA) is predicted to detect
memory directly in loud events from supermassive black hole (SMBH) mergers. We assess the prospects for the cumulative effect of
memory contributions as a
stochastic GW
memory background (SGWMB). Using two SMBH population models, we recover previously obtained single-event SNR forecasts and compute the power spectrum of the unresolved background, using numerical-relativity waveforms for modeling the
memory signal during each event. We find the predicted spectrum is significantly smaller than ones found by modeling the
memory waveform with a Heaviside function, with expected SNRs of order $O(0.1-10)$. We further find that our models favor a highly non-Gaussian ("popcorn") spectrum, demonstrating that the background may not appear as the union of continuous, overlapping signals, but rather as a collection of intermittent bursts. In both measures, we demonstrate that any current prediction of the spectrum is heavily dependent on the choice of population model. We interpret these findings in the light of the future LISA mission and emphasize their importance for properly handling
memory within the LISA global fit.
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Solar and Stellar Astrophysics
Energy redistribution during 2D oscillatory reconnection
Luiz A. C. A. Schiavo, Jordan Talbot, Gert J. J. Botha et al. (+4 more)
Magnetic reconnection is a fundamental energy release mechanism in
solar and space
plasmas. However, the distribution of released
magnetic energy among kinetic and internal (thermal) energy during time-dependent reconnection remains largely unexplored. This work aims to study energy conversion in magnetohydrodynamics via oscillatory reconnection (OR) at a 2D
magnetic null point. Using a shock-capturing code, we identify three families of shocks: termination shocks, slow-mode deflection shocks, and Petschek-like shocks (even with uniform resistivity). We measure the time-dependent reconnection rate, finding a peak of $R \approx 0.1$, consistent with a fast reconnection regime. For the first time, we track the energy conversion pathways between
magnetic, kinetic and internal energy across the time-dependent reconnecting system. We find energy exchange is strongly region dependent, with shock locations dominating over the
diffusion region. In the classical incompressible steady-state reconnection models, the
magnetic energy is fully converted into internal and kinetic energy. In contrast, we find that in compressible time-dependent reconnection, the interchange between kinetic and internal energy dominates the system (due to the inclusion of
plasma compressibility).
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All authors Luiz A. C. A. Schiavo, Jordan Talbot, Gert J. J. Botha, Ben Snow, Daniel Johnson, Madeleine L. Combrinck, James A. McLaughlin
Astrophysics of Galaxies
Extreme Enrichment at Cosmic Dawn: Three FeII-Strong Quasars at z > 6 from the JWST Aether survey
Anniek J. Gloudemans, Emanuele Paolo Farina, Roberto Decarli et al. (+22 more)
We present three outliers on the
quasar main sequence at z>6, as revealed by JWST/NIRSpec IFU observations from the Aether survey, a program targeting ~200
quasars at
cosmic dawn. The
quasars, J0216-5226, J0320-3521, and J1429+5447, exhibit exceptionally strong FeII emission and weak H$\beta$ and [OIII] lines, indicating rapid chemical enrichment within the first Gyr of
cosmic history. Their FeII strengths ($R_{\rm{FeII},\lambda4570} \equiv \rm{EW}_{\rm{FeII}}/\rm{EW}_{\rm{H}\beta}$) range between ~2.5-3.6, placing them among the top ~3% of SDSS
quasars at ($0\lesssim z\lesssim 1$). The H$\alpha$ emission lines of J0216-5226 and J1429+5447 imply black hole masses of $\sim1-7\times10^9$ M$_{\odot}$ with $\lambda_{\rm{Edd}}\sim0.1-0.6$, comparable to typical high-z
quasars, although virial black hole masses may be systematically overestimated in strong FeII emitters. In contrast, J0320-3521 hosts a lower mass black hole of $\sim0.2-2\times10^9$ M$_{\odot}$, suggesting possible super-Eddington rate
accretion with $\lambda_{\rm{Edd}}$~0.5-6.0. The IFU data of J0320-3521 reveal a distinct emission-line region at a projected distance of ~1.5 kpc, consistent with either an interacting companion or ionized gas associated to the
quasar. We further identify a complex environment around J1429+5447, including two candidate companion
galaxies or extended ionized gas structures. These
quasars with bright emission-line regions, J0320-3521 and J1429+5447, are
radio-loud sources, while J0216-5226 remains undetected in
radio ($R_{5\rm{GHz,} \,3\sigma}\lesssim4$). Together, these results confirm previous findings that highly enriched, rapidly growing black holes were already in place at
cosmic dawn. Despite the small sample size, our results further highlight the diversity in environment and
radio-jet properties among
quasars that otherwise share the same extreme region of the
quasar fundamental plane.
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All authors Anniek J. Gloudemans, Emanuele Paolo Farina, Roberto Decarli, Klaudia Protušová, Fabrizio Arrigoni Battaia, Eduardo Bañados, Aaron J. Barth, Silvia Belladitta, Manuela Bischetti, Hyunseop Choi, Dominika Ďurovčíková, Anna-Christina Eilers, Simona Gallerani, Thales A. Gutcke, Luca Ighina, Brian C. Lemaux, Federica Loiacono, Yoshiki Matsuoka, Chiara Mazzucchelli, Silvia Onorato, Hyewon Suh, Fabian Walter, Feige Wang, Julien Wolf, Jinyi Yang
Medical Physics · Cross-listed from eess.SP
Closed-form weak-wave propagation pressure amplitudes for arbitrary power-law attenuation
Esteban Avilés, Michael Oelze, Roberto Lavarello et al. (+1 more)
Biological tissues exhibit power-law frequency dependence of the attenuation coefficient. We derive closed-form weak-wave expressions for fundamental, second-, and third-harmonic pressure amplitudes of monochromatic acoustic plane waves in homogeneous media with arbitrary power-law attenuation to extend classical expressions for quadratic attenuation. For linear frequency dependence of attenuation, one-dimensional simulations using the k-Wave k-space pseudospectral solver yielded 35-42% (classical) and 0-2% (proposed) normalized root-mean-square errors for fundamental-band depletion. This extension supports improved fundamental-band B/A estimation for quantitative ultrasound tissue characterization. A proof-of-concept through-transmission application in phantoms with nearly linear attenuation yielded experimental B/A estimation errors of 23.7-52.7% (classical) and 4.0-5.9% (proposed).
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All authors Esteban Avilés, Michael Oelze, Roberto Lavarello, Andres Coila
High Energy Physics (Theory)
Notes on de Sitter space
Beatrix Mühlmann
We discuss classical and
quantum features of spacetimes with a positive cosmological constant. After introducing basic aspects of de Sitter cosmology and the classical geometry of de Sitter space, we consider de Sitter space both as a rigid background, on which
quantum fields propagate, and as a fluctuating spacetime in its own right. We review the wavefunction of an expanding universe, black holes in de Sitter space, and the de Sitter
entropy, and compare the cosmological horizon with the black hole horizon. The final three sections are dedicated to concrete models of de Sitter space in two, three and four spacetime dimensions.
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Strongly Correlated Electrons
Energy partitioning of wave packets in one-dimensional systems
Flavia B. Ramos, Imke Schneider, Sebastian Eggert et al. (+1 more)
We investigate the non-
equilibrium dynamics of wave packets in a one-dimensional critical fermionic system and analyze the resulting partitioning of energy between emergent excitations. Starting from a Gaussian wave packet injected on top of the many-body ground state, we follow its real-time
evolution using the time-dependent density-
matrix renormalization group. We observe that interactions lead to fractionalization of the initial excitation into counter-propagating left- and right-moving modes, whose energies can be resolved in real space. To interpret these results, we employ Luttinger
liquid theory, which allows us to derive analytical predictions for the energy carried by the emergent modes. We find good agreement between field-theoretical predictions and numerical simulations in the low-energy regime. In contrast to charge fractionalization, which is completely determined by the Luttinger
liquid parameter, we show that energy partitioning is non-universal and depends on details of the injected wave packet, such as its width. Our results provide a real-space characterization of energy partitioning in one-dimensional systems and establish a quantitative comparison between non-
equilibrium numerical simulations and the effective field-theory description.
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All authors Flavia B. Ramos, Imke Schneider, Sebastian Eggert, Rodrigo G. Pereira
Mathematical Physics
Site-scale, Multi-resolution WRF Wind Modeling with Observational Nudging for Methane Emission Monitoring in the Permian Basin
Ehsan Kharazmi, Erin Menezes, George Karniadakis et al. (+2 more)
Accurate methane source localization and emission-rate estimation at oil and gas facilities require wind fields that resolve site-scale spatial and temporal variability, which cannot be characterized by a single anemometer or coarse operational weather products. We develop a multiscale Weather Research and
Forecasting (WRF) framework for a Permian Basin facility that dynamically downscales hourly, 3 km High-Resolution Rapid Refresh (HRRR) fields through four nested domains with grid spacings of 3 km, 1 km, 200 m, and 40 m. The two outer domains use planetary-boundary-layer parameterization, whereas the two inner domains operate in large-eddy-simulation mode. One-minute wind observations from two on-site anemometers are assimilated through wind-only observational nudging in the innermost domain, and the effects of nesting feedback and
turbulence-closure choices are examined. Simulations for winter and summer 2025 periods are evaluated using near-surface wind-speed time series, power spectra, spatial fields, and statistical metrics. The baseline simulation reproduces the broad
evolution of observed wind events but drifts during weak-wind periods. Observational nudging with one- and two-way nesting reduces the absolute bias of wind-speed by %65 at one sensor and %87 at the other, while reducing the corresponding root-mean-square errors by %33 and %44. Nudging also increases high-frequency energy and resolved spatial gradients, although improvements in
turbulence statistics are not uniform. These results demonstrate a practical physics-based pathway for generating high-resolution wind fields for methane-plume modeling while emphasizing the need for independent spatial observations to validate accuracy away from assimilated sensors.
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All authors Ehsan Kharazmi, Erin Menezes, George Karniadakis, Anantha Sundaram, Arash Fathi
Pattern Formation and Solitons
The Origin of Imperfection Sensitivity in the Buckling of Cylindrical Shells
Tian Yang and Tobias M. Schneider
Buckling of thin cylindrical shells under axial compression, a classical example of a subcritical instability, is highly sensitive to small imperfections, with minute
geometric variations causing large changes in buckling threshold. To uncover the origin of this sensitivity, we use numerical continuation and bifurcation analysis while systematically varying the depth and size of a single localized Gaussian defect. We show that the instabilities of the imperfect shell originate from localized
equilibria already present in the perfect shell. By breaking translation
symmetry, the defect pins these
equilibria and changes how they connect to the imperfect base state. Small changes in defect geometry can thereby switch the bifurcation that triggers buckling, producing non-monotonic and discontinuous changes in buckling threshold and abrupt changes in buckling mode. Imperfection sensitivity is therefore not simply sensitivity to imperfection magnitude, but sensitivity of the underlying bifurcation structure to imperfection geometry.
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