Soft Condensed Matter
Oscillatory Active Brownian Motion: A Minimal Model for Sperm Dynamics
Adrian Pacheco-Pozo, Arturo Matamoros Volante, Pilar Ameijeiras et al. (+2 more)
Active biological microswimmers typically combine persistent self-propulsion with cyclic motion generated by flagellar or ciliary beating. However, standard active Brownian motion (ABM) does not explicitly account for these intrinsic oscillations. This limitation is particularly relevant for sperm
cells, whose transport depends not only on directional persistence and
stochastic reorientation but also on periodic head motion. Here we introduce oscillatory active Brownian motion (OABM), a minimal extension of ABM in which the swimmer orientation undergoes directional
diffusion while being modulated by a periodic angular drive. The model yields analytical expressions for experimentally relevant observables, including the time-averaged mean-squared displacement, velocity autocorrelation function, and transverse excursion amplitude. A central prediction is a crossover between two ballistic regimes: short-time motion governed by the swimming velocity and an intermediate regime with a reduced, oscillation-averaged effective velocity determined by the angular beat amplitude. Using trajectories of human sperm, we infer model parameters from standard motility measures. The model quantitatively reproduces both single-
cell trajectories and population-level dynamics under control conditions and following induction of hyperactivation. Overall, OABM provides a compact active-matter framework that links measurable flagellar kinematics to coarse-grained transport, enabling a description of sperm motility across different physiological states.
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All authors Adrian Pacheco-Pozo, Arturo Matamoros Volante, Pilar Ameijeiras, Mariano G. Buffone, Diego Krapf
Mathematical Physics
CORTET: Robust generation of simulation-ready tetrahedral meshes of the fetal cerebral cortex
Davood Shahsavari, Irina Grigorescu, Katherine R. Long et al. (+10 more)
Every human
brain folds differently, and such natural variation confounds the search for imaging biomarkers of neurodevelopmental disorders. Physics-based simulation can help determine the causal mechanisms that underpin this variability. Yet every simulation must be initiated from a volumetric mesh of the
brain's interior, tetrahedral or hexahedral, and it is the worst element in that mesh, not the average, that decides whether the simulation runs at all. Building that mesh from fetal MRI currently requires labour-intensive manual intervention. We therefore present CORTET (CORtical TETrahedral meshing): a fully automated pipeline that converts a triangulated cortical surface into a solver-ready tetrahedral mesh whose worst-element quality meets a strict quality target with no manual repair. By benchmarking against a general-purpose tetrahedral mesher on the same input surfaces, we isolate the pipeline's contribution from that of the input geometry, and we validate quality across a cohort of nearly 200 fetal subjects spanning the folding period. A mesh taken straight from the pipeline sustains a numerically stable morphoelastic folding simulation of a real fetal subject.
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All authors Davood Shahsavari, Irina Grigorescu, Katherine R. Long, Jiaxin Xiao, Kaili Liang, Nashira Baena, Aakash Saboo, Saga N.B. Masui, Yourong Guo, Vanessa Kyriakopoulou, Alena Uus, Martin J. Bishop, Emma C. Robinson
Quantum Physics · Cross-listed from math.NA
Splitting Analysis for Yukawa Potential
Di Fang and Jiaqi Zhang
Splitting methods are among the most classical and fundamental tools for the simulation of
quantum dynamics, and their importance has grown further with the rise of
quantum computing. In this work, we analyze the Schrödinger equation with Yukawa potential, a physically relevant and widely used model potential. It may be viewed as a Coulomb interaction with exponential decay at spatial infinity, preserving the Coulomb singularity at the origin while removing the long-range Coulomb tail. We prove that the operator splitting for this unbounded
Hamiltonian achieves a global $1/4$-order convergence rate in the time step for many-body Yukawa interactions, with explicit
polynomial dependence on the number of particles. The result holds for all initial wavefunctions in $H^2(\mathbb R^{3N})$, the natural domain of the
Hamiltonian, and our numerical experiments are consistent with the theoretical estimates. To identify the sharp obstruction behind this rate, we prove a short-time lower bound in the one-body setting of order $t^{5/4}$ for the one-step error, which rules out any uniform global estimate of order better than $1/4$ in general. This agreement with the optimal $1/4$ rate in the Coulomb case is particularly interesting, as Yukawa potential is short-ranged compared to Coulomb potential. For the many-body upper bound, one of the new technical ingredients is the explicit
polynomial-in-system-size Sobolev estimates of many-body Yukawa systems. These estimates are crucial for obtaining fully a priori bounds that depend only on the norms of the initial states, rather than on the solution at time $t$. For the one-body lower bound, we leverage a new analysis argument based on
Fourier analysis and Kato smoothing.
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General Relativity and Quantum Cosmology
High-order gravitational late-time tails in Kerr spacetime
Marc Casals, Chris Kavanagh, Jakob Neef et al. (+1 more)
We calculate high-order late-time tails of the retarded Green function of the Teukolsky equation for linear field perturbations of (subextremal) Kerr spacetime. We calculate these tails at a fixed spheroidal harmonic $\ell$ and azimuthal number $m$ up to the first three orders for the field point: at finite radius (away from the event horizon) for large Boyer-Lindquist time $t$; along the future event horizon $\mathscr{H}^+$ for large ingoing Eddington-Finkelstein coordinate $v$; and along future null infinity $\mathscr{I}^+$ for large outgoing Eddington-Finkelstein coordinate $u$. We obtain the tail powers for generic integer field
spin $s$ and the tail coefficients specifically for gravitational ($s=-2$) perturbations. Our asymptotics include the known leading power-law (generic) tails, respectively,$t^{-2\ell-3}$, $e^{im\Omega_H v}v^{-2\ell-3-b}$ (where $b=1$ for $s>0, m=0$ and $b=0$ otherwise, and where $\Omega_H$ is the angular velocity of the event horizon) and $u^{-\ell+s-2}$, as well as their higher-order logarithmic corrections: $t^{-2\ell-5}\ln t$, $e^{im\Omega_H v}v^{-2\ell-5-b}\ln v$ and $u^{-\ell+s-3}\ln u$ (as well as $u^{-\ell+s-4}\ln^2 u$). Since we obtain the high-order expansions for modes for generic $\ell$ and $m$, we can readily infer the explicit expansions of the full retarded Green function for $s=-2$ (and its decay powers for generic integer $s$). We obtain the late-time asymptotics from small-frequency expansions of the
Fourier modes of the retarded Green function in the frequency domain. Accordingly, we also provide small-frequency expansions of various quantities of interest in the scattering theory. We also attach two notebooks which provide expansions for specific values of $s$: one notebook provides them to the first three leading orders for generic $\ell$ and the other one to arbitrary order for specific values of $\ell$.
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All authors Marc Casals, Chris Kavanagh, Jakob Neef, Adrian Ottewill
Astrophysics of Galaxies
A differentiable hydrodynamical approach to the Milky Way bar pattern speed with CO longitude–velocity data
Junichi Baba and Kohei Hattori
We present a differentiable hydrodynamical framework for modeling barred gas flow in the Milky Way and constraining broad low-loss regions in bar-pattern-speed parameter space from
Galactic longitude–velocity data. The method evolves a neutral-gas disk in a fixed barred potential, projects it into longitude–velocity ($\ell$–$v$) space, and compares predicted and target maps using a cosine-distance loss applied to processed and masked maps. This emphasizes large-scale morphology rather than the absolute emission scale. Because the forward model is differentiable, gradients with respect to the bar pattern speed can be computed and used for direct optimization in observable space. We validate the method with self-consistency hydrodynamical mocks and with an independent mock generated by a different solver with more realistic interstellar-medium physics. These tests recover or identify low-loss regions near the input pattern speed, showing that the method captures coherent bar-driven structures in $\ell$–$v$ space. We then apply the framework to the observed CO $\ell$–$v$ structure of the inner Milky Way. The data yield broad low-loss regions rather than a unique best-fitting value. These regions include moderate pattern speeds, $|\Omega_{\rm b}|\sim30$–$40\,{\rm km\,s^{-1}\,kpc^{-1}}$, consistent with current
stellar-dynamical constraints, although their location depends on the gas response time and viewing angle. This first application demonstrates the feasibility of differentiable hydrodynamical modeling of
Galactic gas as an independent kinematic test of barred Milky Way models and as a step toward multi-parameter forward modeling in position–position–velocity space.
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Cosmology and Nongalactic Astrophysics
Solar System Probes for Scalar Field Dark Matter
Edmund Ghampson, Oem Trivedi, Robert J. Scherrer et al. (+1 more)
Scalar field dark matter provides us with a well motivated alternative to conventional particle dark matter, especially when ultralight fields form coherent oscillations or compact self gravitating clumps. Here we develop three complementary
Solar System and local
Galactic level probes of such models. These probes pertain to ADAF-like
flares from scalar clump encounters with Kuiper Belt Objects, atomic clock searches for oscillatory variations of fundamental constants and astrometric microlensing by compact scalar clumps. We derive simple sensitivity estimates and null detection bounds on the scalar clump fraction, clock couplings and compact lens abundance. Our results show that
Gaia-like astrometry can probe compact scalar clumps at the percent level near $M_s\gtrsim10^{-2}M_\odot$, while future astrometric and clock experiments can extend the reach to lower masses and weaker couplings.
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All authors Edmund Ghampson, Oem Trivedi, Robert J. Scherrer, Alfredo Gurrola
High Energy Physics (Theory)
Computational homological methods for integrable field theories
Marco Benini, Ryan A. Cullinan, Alexander Schenkel et al. (+1 more)
We develop explicit computational tools for the recent homological approach to the construction of $2$-dimensional integrable field theories on $\Sigma$ from $4$-dimensional semi-holomorphic Chern-Simons theory on $\Sigma \times C$. In this framework, the operation of integrating out the spectral curve $C$ is realized by homotopy transfer of a cyclic $L_\infty$-
algebra associated with the $4$-dimensional theory with prescribed singularities and boundary conditions. We construct explicit strong deformation retracts for divisor-twisted Dolbeault complexes on $C=\mathbb{C}P^1$ and use them to make the transferred $L_\infty$-structure computationally accessible. As an application, we study the choice of meromorphic $1$-form corresponding to the principal
chiral model with a Wess-Zumino term. We compute the transferred Maurer-Cartan action and the associated Lax connection, showing that the former resums to the standard principal
chiral model action with a Wess-Zumino term and that the latter reproduces the usual Lax connection.
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All authors Marco Benini, Ryan A. Cullinan, Alexander Schenkel, Benoit Vicedo
High Energy Physics (Theory)
Superconductive or superfluid condensation in curved spacetime
Leonardo Modesto
We provide a proof of unitarity for
quantum field theory in a general spacetime. Our argument expresses the Bogoliubov transformations in terms of a
unitary squeezing operator relating the initial and final
Hilbert spaces. The $S$-
matrix in curved spacetime is thus the product of the squeezing operator and the $S$-
matrix in the out-
Hilbert space (typically Minkowski). Since both factors are
unitary, their product is
unitary. It follows that the Bogoliubov in-
vacuum is described by a BCS-like state (Bardeen–Cooper–Schrieffer): (i) for
fermions, it is exactly the BCS state, but with electrons and positrons in place of electrons with opposite
spin; (ii) for
bosons, it is the Bose–Einstein condensate (BEC) superfluid ground state. Thus,
gravity, or an accelerating force, creates from the
vacuum a many-particle system unstable towards forming a new ground state of Cooper pairs. Technically,
gravity converts the
vacuum into an electron-positron condensate, with respect to which
quantum field theory evolves unitarily. By reverse engineering, we reconstruct the effective
Hamiltonian of QFT in a black hole (or Rindler) background, together with a simple formula for the mass gap function, which grows approximately linearly with the temperature. Hence, electrons and positrons condense into a superconducting state at increasingly higher temperatures as the black hole mass decreases. Unitarity and the particle interpretation are preserved at every stage of evaporation. The Hawking state is exactly a BCS state. Finally, we compute the
entanglement entropy and derive the area law.
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Astrophysics of Galaxies
Discovery of a gravitational arc candidate at photometric redshift 1.4 in MACS J0308.9+2645 from a catalogue-based search of JWST imaging
Homer Dávila Gutiérrez
We report a previously uncatalogued gravitational arc candidate (A1) in the massive RELICS cluster MACS J0308.9+2645 (z_l = 0.356), identified in public JWST/NIRCam imaging from programme GO-5293 through a transparent catalogue-based selection of extended, elongated, tangentially aligned sources. A1 has axis ratio a/b ~ 6.5, isophotal extent ~ 5.1 arcsec, and lies 50.9 arcsec from the cluster X-ray centre, tangentially aligned to within 1.4 +/- 3.0 deg. We show that the catalogue aper_total_abmag photometry, designed for unresolved sources, is invalid for this extended arc: the aperture captures only a few per cent of the isophotal flux and, because its radius grows with wavelength, imposes ~ 1.4 mag of spurious red colour that would drive a spurious high-
redshift solution. Extended-source photometry (isophotal, fixed matched apertures, curve-of-growth) combined with archival HST/RELICS forced photometry in seven bands yields z ~ 1.4 (range 1.2-1.7). A significant HST/ACS F435W detection independently excludes the high-
redshift solution, which would require a complete Lyman-limit dropout. At z ~ 1.4 the public Zitrin-LTM-Gauss lens model places A1 near the tangential critical curve in the single-image regime: full-map ray-tracing predicts no counter-images for z < 2, consistent with the absence of any counterpart, whereas a z = 4.4 source would require a counter-image of m ~ 22.7 where none is observed. The most probable interpretation is a singly lensed
galaxy at z ~ 1.4 behind the cluster. The arc's
curvature is concave toward the cluster centre (radius ~ 19 arcsec) but of marginal, method-dependent significance once correlated noise is accounted for. A fainter arclet (A2) is retained as a secondary candidate. Spectroscopy and a dedicated lens model are required for confirmation.
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Quantum Physics
Categorical Tensor-Graph Semantics for Quantum Algorithms
Naihong Hu, Ruining Li and Futao Wang
This paper investigates foundational
quantum computing protocols from the intuitive perspective of categorical tensor-graph semantics within the category FHilb. While conventional
Hilbert-space formalisms often conceal the structural nature of
quantum algorithms behind high-dimensional
matrix operations, the topological framework directly encodes algorithmic functionalities into their graphical skeletons. We provide a comprehensive topological reinterpretation of the Bernstein–Vazirani and Simon
algorithms, demonstrating how topological transformations distill their core mathematical essence and clarify the operational mechanisms of oracles. Going beyond the standard
qubit model, we construct explicit representations for the qutrit-adapted topological Deutsch–Jozsa and single-shot Grover
algorithms. In particular, we establish a necessary and sufficient condition for the single-shot Grover search. We further implement CNOT gates via complementary Frobenius structures and investigate a diagrammatic decomposition scheme for the W-state preparation protocol. By bridging tensor category theory with practical
quantum algorithmic design, this work furnishes a composable, scalable diagrammatic toolkit essential for automated
circuit optimization across the evolving
quantum hardware ecosystem.
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High Energy Physics (Theory)
Compact, long-range and vacuumless regimes controlled by scalar fields in two-dimensional flat and five-dimensional warped geometries
Elisama E.M. Lima and Dionisio Bazeia
We investigate the presence of compact, long-range, and vacuumless regimes in models described by real scalar fields in 2D flat and 5D warped geometries. In the two-dimensional case, we study in detail several models that support localized solutions. When embedded into a warped $\text{AdS}_5$ background, these fields generate distinct kinds of brane profiles.
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Quantum Physics
Error correction on an array of superconducting qubits with defective components
Julien M. Drouet, Xanda C. Kolesnikow, Campbell K. McLauchlan et al. (+6 more)
A solid-state
quantum-computing architecture will require the fabrication of arrays of many coupled
qubits. It is inevitable that this process will produce
qubits and couplers with varying performance, with some components underperforming due to imperfect fabrication.
Quantum error-correction requires high-performing components and hence these defects must be dealt with, either by adapting the code to exclude the defects, or by informing the decoder to accommodate defects in post-processing. Here we implement and compare strategies to operate distance-5 surface codes on a
quantum processor consisting of a square-
lattice array of 120 superconducting
qubits. We demonstrate a dramatic reduction in the probability of a logical error in a
memory experiment by excluding underperforming components, compared with both a standard approach of ignoring defects, and a defect-aware decoding approach. We observe up to 2.8X improvement in logical errors per round when excluding defects compared with the standard defect-ignorant approach (1.62% compared to 4.49%). In contrast, defect-aware decoding gives only modest gains. Defects are also expected to be particularly harmful for measurement-based logical operations. Using a stability experiment we show that excluding defects resurrects measurement-based logic gate performance, observing a 6.3% per-round suppression of failure rate when excluding defects, compared to zero suppression otherwise. Furthermore, we show a further substantial decrease in logical errors when using leakage post-selection in combination with our defect exclusion strategies, resulting in a distance-5 code outperforming the best distance-3 in one basis. Our experiments therefore give a proof-of-principle demonstration of the essential utility of defect exclusion methods in the scale-up of solid-state
quantum computing approaches.
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All authors Julien M. Drouet, Xanda C. Kolesnikow, Campbell K. McLauchlan, Georgia M. Nixon, Seok-Hyung Lee, Dominic J. Williamson, Stephen D. Bartlett, Benjamin J. Brown, Robin Harper
Physics and Society · Cross-listed from cs.SI
Stop using Media Bias/Fact Check in research
Alejandro Javier Ruiz Iglesias, Julia Witte Zimmerman, Ashley M.A. Fehr et al. (+2 more)
Media Bias/Fact Check (MBFC) purports to quantify the bias, credibility, and factuality of reporting for roughly 10,000 media sources, and the resulting data is commonly used in misinformation research. In the present study, we show that MBFC's methodology does not meet basic standards of rigor for academic research. Despite its widespread prevalence, studies using MBFC rarely examine it carefully, often describing it in ways that contradict its “About” page, or treating it as authoritative despite MBFC's disclaimer that it is “not a tested scientific method... [but] a simple guide to the idea of a source's bias.” We identified no papers that adequately describe MBFC as the opinions of a single person or critically engage with its methodology in order to justify proceeding with its use. We argue that MBFC's data is not neutral or accurate, but a computationally legible account of hegemony, a specious
dataset for uncritical research that mistakes the familiarity of the concepts it quantifies with accuracy. Our study concludes with a call for academic researchers to stop using MBFC. MBFC's data quantifies the results of political processes, including campaigns to discredit the press, and presents them as simple facts about the world, thus reproducing the crisis misinformation scholarship exists to address.
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All authors Alejandro Javier Ruiz Iglesias, Julia Witte Zimmerman, Ashley M.A. Fehr, Peter Sheridan Dodds, Christopher M. Danforth
Instrumentation and Methods for Astrophysics
The Interstellar Laser Beacons Hypothesis and the Cosmic Lighthouses Project
Daniel Apai, Chia-Lung Lin and Kevin Wagner
In this paper, we argue that in a realistic, resource-limited scenario senders whose intent is to maximize successful communication at the lowest cost will utilize very long-lived, pulsed beacons. Further, we argue that mass-producible
laser beacons with simpler technology ($\mu$s or ms pulses instead of ultrashort fs pulses) are more optimal if placed on interstellar orbits. Our extensive, existing surveys are mostly blind to the $\mu$s/ms-second universe and to such beacons. We show, however, that the convergence of three technologies (massively parallel processing, ultra high-speed CMOS detectors, and broadband, mass-producible diffractive-refractive lenses) now offer an exciting opportunity for a low-cost survey of the $\mu$second sky. Such survey would be astrophysically compelling and, with even low-cost
telescopes, could place volume-complete constraints on interstellar beacons within twenty parsecss.
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High Energy Physics (Theory)
Liouville strings in AdS$_3$: the worldsheet story
Gaston Giribet and Pedro Schmied
The worldsheet $\sigma$-model of strings on AdS$_3$ with NS-NS fluxes can be equivalently described in terms of a Liouville field theory coupled to a timelike field with background charge, plus a marginal deformation. The operator that produces the deformation is non-normalizable and, from the string theory perspective, is associated to the spectral flow sector $\omega =2$. Its role is to control the winding number violation in scattering amplitudes. In the semiclassical (large $k$) limit, the central charge of the Liouville factor tends to that of the dual CFT$_2$, namely $c\simeq 6k$. This may appear very similar to what occurs in the Liouville-type description of the dual deformed orbifold CFT$_2$, where a twist-2 deformation operator dressed with a non-normalized field also appears. Indeed, there are some similarities to that; however, there are also significant differences, which we discuss.
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Mesoscale and Nanoscale Physics
Analytical and numerical solutions to the non-diffusive Stefan problem
Matthew Van Ham, Minghan Xu and Samuel Huberman
In this work, the Maxwell–Cattaneo–Vernotte (MCV) equation is used to model the one-dimensional
hyperbolic Stefan problem in the limit of a small Stefan number (Ste $\ll$ 1). The solutions are approximated with perturbation series expansions using a reformulation in which time is expressed as a function of the solid-
liquid interface position. The first proposed solution is derived in a framework that considers diffusive heat transfer at the phase change interface, for analytic tractability. Two rectification strategies are proposed to address the asymptotic divergence present in this formulation: a rescaled inner solution which is then combined with the outer solution to yield a composite solution, and size-dependent thermo-physical system parameters for better capture of
hyperbolic effects at the phase change interface. The resulting interface profiles exhibit a characteristic
parabolic-like shape, consistent with diffusive Stefan problem findings, with pronounced early-time
hyperbolic effects at larger thermal relaxation times. Parametric studies are done over three pertinent variables in the dimensionless system: the Stefan number ($\mathrm{Ste}$), the dimensionless thermal relaxation time ($\widetilde \tau$), and the thermal diffusivity ($\alpha$). The studies suggest that model error scales with the Stefan number in accordance with the theoretical truncation error of the perturbation expansion. Additionally, larger values of $\widetilde \tau$ amplify early-time
hyperbolic effects, thereby increasing model error, while larger $\alpha$ extends the relative temporal domain over which these
hyperbolic effects remain significant, also corresponding to an increase in model error.
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Quantum Physics
Defeating Barren Plateaus with Task-Aligned Symmetry
Ruipeng Xing, Yanan Li, Zhen Shang et al. (+3 more)
Barren plateaus – the exponential vanishing of gradients – are a fundamental obstacle to training scalable
quantum neural networks. Whether they arise in
quantum recurrent neural networks (QRNNs), a natural architecture for sequential data, remains a pressing question. Here we show that the decisive ingredient for trainability in QRNNs is not the recurrent
circuit topology per se, but enforcing time-translation
symmetry through parameter sharing across time steps. We prove that, without parameter sharing, QRNNs suffer from barren plateaus, with gradient variance decaying exponentially with sequence length. Imposing parameter sharing across time steps fundamentally alters this scaling, transforming it into a
polynomial dependence and thereby suppressing the barren plateau. Numerical simulations corroborate these analytical predictions. By rigorously showing how time-translation
symmetry suppresses barren plateaus and enhances learning capability in QRNNs, our work establishes task-aligned
symmetry as a constructive resolution to the expressivity-trainability tension in
quantum neural networks.
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All authors Ruipeng Xing, Yanan Li, Zhen Shang, Shengbin Wang, Yongjian Gu, Zhimin Wang
Statistical Mechanics
Topological building blocks of nonequilibrium response
Sean Fancher and Jordan Horowitz
Nonequilibrium systems can exploit energy to amplify their sensitivity to external stimuli, allowing them to be harnessed for a variety of functions in both engineered devices and living organisms. An assortment of theoretical results capture different facets of this nonequilibrium amplification, including fluctuation-response relations as well as bounds and constraints that limit the potential behavior. Here, we take a broader perspective, aiming for a systematic characterization of the full range of possible response behaviors. For a wide class of nonequilibrium dynamics, we identify a collection of optimally sensitive models whose behavior is determined by the
topology of the state space. We further
conjecture that every response can be written as a convex combination of these optimal models, thereby structuring the entire space of responses. We use this
geometric perspective to put sensitivity limits on nonmonotonic biochemical input-output functions, and identify all optimal kinetic schemes for the unordered binding of molecules among three sites.
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Statistical Mechanics
Harvesting Reshapes Dynamical Populations
R. K. Singh, Michael Assaf, Jason R. Green et al. (+1 more)
Harvesting – the periodic removal of individuals above or below a threshold trait value – reshapes heterogeneous populations without altering their underlying
stochastic dynamics. We study how repeated harvesting events steer the
evolution of probability densities for classes of
stochastic processes exhibiting both normal and anomalous dynamics, as well as a prototypical predator-prey model. Removal of the upper portion of the density drives the system to a quasi-steady state when viewed at the “harvesting clock”. This state depends only on the harvesting threshold and frequency but not on the initial conditions. Removal of the lower portion of the density fixes its shape while generating a constant effective drift that exceeds that of the unharvested mean. Our results suggest the possibility of manipulating the dynamics of
stochastic populations through external selection interventions.
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All authors R. K. Singh, Michael Assaf, Jason R. Green, Erez Aghion
Earth and Planetary Astrophysics
TESS Photometry and Radial Velocity Analysis of the sub-Neptune Exoplanet {\pi} Mensae c and the Wider {\pi} Mensae Planetary System
Skylar S. Larsen, Jake D. Turner, Nikole K. Lewis et al. (+10 more)
Exoplanet characterization relies on precise measurements of planetary orbital and physical parameters. This is particularly important for planetary dynamics and atmospheric
evolution, as orbital parameters help constrain system
evolution, resolve ambiguities, and gauge atmospheric retention. The first
exoplanet discovered by the Transiting
Exoplanet Survey Satellite (TESS), $\pi$ Men c, is a warm sub-Neptune orbiting a bright Sun-like
star in a system containing (at least) one other
planet with a wildly different period and size. Lying near the 1.5-2.0 $R_{\oplus}$ radius gap, $\pi$ Men c is expected to have lost its
primordial hydrogen and helium, but kept heavier compounds like H$_2$O and CO$_2$. The $\pi$ Men system is well observed with decades of radial velocity measurements, and TESS has continued to observe $\pi$ Men c, yielding six years and 21 sectors of photometry. We present a comprehensive analysis of these TESS data and 22 years of radial velocity measurements to provide updated orbital ephemerides for $\pi$ Men b, c, and the proposed third
planet, $\pi$ Men d. Our newly derived $\pi$ Men c period error margins are an order of magnitude improved from previous estimates, and we estimate the mass range of $\pi$ Men d to be 13.4 $\leq$ M$_d$ $<$ 20 M$_{\oplus}$. We find that $\pi$ Men c is a uniquely interesting target for future transmission spectroscopy studies with JWST, and that existing radial velocity data are consistent with the existence of a third
planet.
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All authors Skylar S. Larsen, Jake D. Turner, Nikole K. Lewis, Maryame El Moutamid, Diana Solano-Oropeza, Lili Alderson, V. Abby Boehm, Daniel A. Yahalomi, Emily K. Deibert, Ray Jayawardhana, Dong Lai, Adam B. Langeveld, Kyle A. Pearson
Astrophysics of Galaxies
Illuminating M82: Simulating X-ray Emission from Galactic Winds in a Starburst Galaxy
Allison Lin, Lachlan Lancaster, Viraj Pandya et al. (+6 more)
We generate mock X-ray observations from a suite of idealized high-resolution ($\sim 4$ pc), tall-box ($\sim 2 \times 2 \times 8$ kpc$^3$) simulations of
star formation driven
galactic winds in an M82-like system, varying the spatial resolution as well as the strength and distribution of
supernova (SN) energy injection. We compare our mock X-ray observations with deep Chandra observations of the hot
plasma around M82. While the simulated total X-ray luminosity, $L_X$, increases with resolution and when SNe feedback is spatially distributed, even in the best case scenario, our simulated $L_X$ is a factor of $\sim 50-100$ lower than observed and the surface brightness profiles of X-ray emission, $S_X(z)$, fall off too quickly with distance from the
galaxy. Past results were able to reproduce these observables and we discuss potential simulation differences that could explain this discrepancy. We make the first comparison of the X-ray spectrum of our simulations to observations and find that our simulated spectrum is too soft, with a deficit of hard X-ray
photons at $\gtrsim 1$ keV. We discuss how physical processes missing from our simulations and prior work (e.g., thermal conduction and
cosmic rays) could help resolve this discrepancy.
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All authors Allison Lin, Lachlan Lancaster, Viraj Pandya, Drummond B. Fielding, Greg L. Bryan, John A. ZuHone, Sebastian Lopez, Laura A. Lopez, Christopher Carr
High Energy Physics (Theory)
Composite worldline instantons and the nonperturbative particle decay in constant external electric and magnetic fields
Alexander Gorsky and Ivan Poluboyarinov
In this paper, we discuss the validity of the composite worldline instanton approach for the nonperturbative decay of charged particles in constant electric and
magnetic fields. It is shown that the instanton results in the leading exponential approximation in the different limits agree with the ones obtained by the imaginary part of the self-energy in the external field and by overlap of the wave functions. We comment on the possible application of our results for the estimation of the decay rate of the
proton in the external electric and
magnetic field in the leading exponential approximation. The effects of
entanglement of the particles in the final state are briefly mentioned.
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Earth and Planetary Astrophysics
MOA-2020-BLG-108Lb: A Giant Planet Beyond the Snow Line of a Low-Mass Lens Near the Lower Boundary of the Mass-Ratio Desert
Yuki K. Satoh, David P. Bennett, Takahiro Sumi et al. (+21 more)
We present an analysis of the microlensing event MOA-2020-BLG-108, which was discovered in June 2020 by the MOA collaboration toward the
Galactic bulge. The observed light curve shows significant deviations from the standard single-lens single-source model. We find two degenerate binary-lens single-source solutions, corresponding to the wide and close configurations, with a companion-to-host mass ratio of $q\sim0.02$ and projected host–companion separations of $s=1.33\pm0.01$ and $s=0.76\pm0.01$, respectively. These solutions improve the fit by $\Delta\chi^2>4430$ compared to the single-lens model. We detected the finite-source effect in the light curve and obtained the angular Einstein radius of $\theta_{\rm E} = 0.7\pm0.1\:\mathrm {mas}$, which provides a mass–distance relation for the lens. We conducted a
Bayesian analysis to estimate the physical parameters of the lens system. The results indicate that the lens system consists of a host
star with a mass of $M_{\rm L,H} \sim 0.6\:M_\odot$ at a distance of $D_{\rm L}\sim5$ kpc and a
giant planet with a mass of $M_{\rm L,C}\sim10\:M_{\rm {Jup}}$ orbiting beyond the snow line. Conventional
planet formation theories suggest that
giant planets are unlikely to form around low-mass
stars. Furthermore, several statistical studies have suggested the existence of a companion-to-host mass-ratio desert in the range $0.02 \lesssim q \lesssim 0.05$, and the companion in the lens system discovered in this work lies near the lower boundary of this desert. Objects near the
planet-brown
dwarf boundary may form through multiple pathways, and this discovery provides an additional data point for understanding their formation mechanisms.
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All authors Yuki K. Satoh, David P. Bennett, Takahiro Sumi, Ian A. Bond, Nicholas J. Rattenbury, Daisuke Suzuki, Naoki Koshimoto, Shota Miyazaki, Rintaro Kirikawa, Fumio Abe, Aparna Bhattacharya, Ryusei Hamada, Stela Ishitani Silva, Yuki Hirao, Yutaka Matsubara, Yasushi Muraki, Tutumi Nagai, Kansuke Nunota, Greg Olmschenk, Clément Ranc, Sean K. Terry, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama
Materials Science
Hyperfine Structure and Exchange Coupling of Vacancy-Induced Ce$^{3+}$ Spin Centers in Nuclear-Spin-Dilute CeO$_2$
T.M. Chithresh and Rudra Banerjee
Oxygen vacancies in ceria CeO$_2$ donate electrons that localize as Ce$^{3+}$ ($4f^1$, $S=1/2$) small polarons, creating rare-earth
spin centers through native defect chemistry rather than implantation or extrinsic doping. We investigate the
magnetic environment of these centers using first-principles PBE$+U$ calculations with a linear-response Hubbard parameter ($U=5.8382$ eV), hyperfine tensors from the all-electron reconstruction of the projector-augmented-wave method, and Korringa-Kohn-Rostoker exchange calculations within the coherent-potential approximation. Four vacancy configurations spanning concentrations from $3.125\%$ to $12.5\%$ are considered. A distinctive feature of the host follows from cerium isotopics: all naturally occurring cerium isotopes possess
nuclear spin $I=0$, eliminating on-site hyperfine interactions at the Ce$^{3+}$ center and leaving the
nuclear-
spin bath entirely on the oxygen sublattice, whose sole
magnetic isotope, $^{17}O$ ($I=5/2$), occurs at $0.038\%$ natural abundance. The resulting $^{17}O$ hyperfine landscape consists of a small number of strongly coupled, nearly axial first-shell
nuclei with contact couplings reaching $6$~MHz, surrounded by a weakly coupled and strongly anisotropic outer shell. These tensors define experimentally accessible signatures for $^{17}O$ ESEEM and HYSCORE measurements and provide the microscopic hyperfine parameters required for cluster-correlation-expansion calculations of
spin coherence. Exchange interactions between neighboring polarons are weak and oxygen-mediated, leaving the vacancy-generated
spins largely independent over the concentration range considered. Together, these results establish oxygen-deficient CeO$_2$ as a chemically generated and intrinsically
nuclear-
spin-dilute host for rare-earth
spin centers, and provide the first-principles
magnetic parameters needed to assess their coherence properties.
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Astrophysics of Galaxies
Tracing cosmic star formation history through radio continuum spectral energy distribution and non-thermal emission
Fangxia An, Fatemeh S. Tabatabaei, Nick Seymour et al. (+11 more)
As a tracer of massive
star formation unaffected by
dust, the
radio continuum emission provides a unique window into the formation of the first
stars and
galaxies in the Universe. Recent observations show that the integrated rest-frame mid-
radio (~1-10 GHz) luminosity of
galaxies serves as one of the most robust tracers of the
star formation rate (SFR). These studies further demonstrate that the synchrotron spectral index and the shape of the
radio spectral energy distribution (SED) evolves with
redshift as a consequence of the
cosmic evolution of
star formation activity. These findings underscore the importance of deep multi-band
radio continuum observations in calibrating the SFR of early
galaxies and understanding the astrophysical processes governing their assembly and
evolution over
cosmic time. This chapter presents recent progress in
radio SFR calibrations for
star-forming
galaxies (SFGs) and reviews
radio-continuum studies of the
cosmic star formation history (SFH). We highlight the transformative potential of SKA AA4, whose broad frequency coverage and high sensitivity will enable well-constrained
radio SEDs for SFGs across a wide
redshift range.
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All authors Fangxia An, Fatemeh S. Tabatabaei, Nick Seymour, Maryam Khademi, Zunli Yuan, Wenjie Wang, Joe A. Grundy, Mark T. Sargent, Tao Wang, Yuheng Zhang, Yinghe Zhao, Hiddo S. B. Algera, Elias Brinks, Mattia Vaccari
Earth and Planetary Astrophysics
I Can Do It With A Broken Planetesimal: Characterising the planetary debris in heavily polluted cool white dwarfs
Anna-Maria Cutolo, Boris T. Gänsicke, Andrew Swan et al. (+7 more)
We present the analysis of four cool and strongly metal-polluted H-atmosphere white
dwarfs observed with X-shooter. We compared their atmospheric parameters obtained from spectroscopy, photometry and a hybrid method, finding a difference of up to $\simeq160$ K in $T_\mathrm{eff}$, and $\simeq0.3$ dex in $\log g$, between the three analyses. We adopt the $T_\mathrm{eff}$ and $\log g$ from the photometric analysis, and subsequently measured the metal abundances of the photospheric elements from spectroscopic modelling, analysing their compositions. We identified from five to eleven unique metals in the photospheres of the four white
dwarfs, with total
accretion rates ranging from $10^{8}$ to $10^{9}$ $\mathrm{g~s^{-1}}$. The compositional analysis of WD J035826.49$+$215726.16 suggests an accreted planetesimal akin to a core-rich differentiated body, with a core mass fraction of 70 per cent, placing it among the most core-rich objects known to be accreted by white
dwarfs. The parent body accreted by WD J042643.98$-$415341.44 shows an enhancement in Na compared to that of the Earth, making it most similar to primitive chondrites. The photosphere of WD J013222.88$+$052923.71 is greatly depleted in core-like material, and its composition resembles that of pure crust/mantle material. WD J232428.21$-$021643.65 has accreted the most Fe-rich planetesimal, with an Fe mass fraction of 67 per cent. We compare these results to other published studies and conclude that these white
dwarfs are among the most heavily polluted cool DAZs studied to date, increasing the sample of cool H-dominated white
dwarfs with five or more metals by 50 per cent.
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All authors Anna-Maria Cutolo, Boris T. Gänsicke, Andrew Swan, Andrew M. Buchan, Jamie T. Williams, Detlev Koester, Paula Izquierdo, Mark A. Hollands, James A. Blake, Nicola P. Gentile Fusillo
High Energy Physics (Theory)
Low-temperature Quantum-corrected Holographic Transport with Momentum Relaxation
Suman Das, Sabyasachi Maulik, Leopoldo A. Pando Zayas et al. (+1 more)
We determine the
quantum corrections to transport arising from fluctuations of the near-AdS${}_2$ throat of near-extremal black branes in
holographic models with momentum relaxation. By computing the shear viscosity and electrical conductivity at both zero and finite chemical potential, we uncover a universal low-temperature enhancement of transport generated by Schwarzian
quantum fluctuations. Specifically, transport coefficients extracted from retarded Green's functions increase throughout the regime $C T \ll 1$. For operators with Schwarzian scaling dimension $\Delta >1$, this enhancement is preceded by a universal minimum at a characteristic temperature $T_{\rm min} \propto C^{-1}$, leading to a non-monotonic temperature dependence strikingly similar to that observed in many correlated materials. In contrast, for the case $\Delta =1$, relevant for the electrical conductivity, the transport coefficient evolves monotonically toward a constant value. Our results identify universal signatures of near-horizon
quantum gravity in the transport properties of
holographic quantum matter.
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All authors Suman Das, Sabyasachi Maulik, Leopoldo A. Pando Zayas, Jingchao Zhang
High Energy Physics (Theory)
Low-Temperature Holographic Conductivity
Sabyasachi Maulik, Leopoldo A. Pando Zayas and Jingchao Zhang
We revisit
holographic electrical conductivity in the regime of very low temperatures where
quantum fluctuations in the throat of the near-extremal, asymptotically AdS$_4$ dual black brane are strongly coupled. We treat the fluctuations via an effective two-dimensional action capturing the effects of the Schwarzian modes at the scale $1/C$. Our main result is a non-monotonic temperature dependence: the
quantum-corrected conductivity decreases as the temperature is lowered, reaches a minimum at $(CT_{\mathrm{min}}\simeq 0.023)$, and grows as $(1/\sqrt{CT})$ for $(CT\ll 1)$. We further estimate the one-loop contribution to the conductivity directly from the four-dimensional gravitational path integral and find qualitative agreement with the effective two-dimensional description in the regime $(CT\gg 1)$. We find that
quantum corrections substantially modify the low-temperature behavior of the
holographic conductivity in both approaches.
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Quantum Physics
Gleydson Fernandes de Jesus, Bruno Oziel Fernandez and Marcelo A. Moret
Molecular docking is an important step in drug discovery, enabling the evaluation of receptor-ligand affinity while reducing experimental costs and increasing the number of possible tests. However, the high computational cost associated with molecular docking remains a limiting factor that can restrict both the experimental precision and the scale of the problems being addressed. To improve the future applicability of molecular docking, recent works have proposed the use of
quantum algorithms based on Gaussian
Boson Sampling
quantum computers and also gate-based
quantum computers. In this work, we propose the use of
Quantum Circuit Evolution (QCE) for solving the molecular docking problem, a gate based and gradient-free
quantum evolutionary method whose
evolution is driven by the random application of
unitary operations to a
quantum circuit. The proposed
algorithm demonstrated the ability to find the best solution to the problem in fewer steps than the methods presented in previous studies, exhibiting fast and stable convergence.
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Quantum Physics
HarmQ: Harmonic Backdoor Attacks Against Quantum Neural Networks
Junrui Zhang, Zemin Chen, Chunsheng Xin et al. (+2 more)
Quantum Neural Networks (QNNs) have emerged as a promising paradigm for
quantum machine learning in the Noisy Intermediate-Scale
Quantum (NISQ) era, leveraging
quantum phenomena such as superposition and
entanglement to process information in exponentially large
Hilbert spaces. However, QNNs inherit critical security vulnerabilities from classical neural networks, particularly susceptibility to
backdoor attacks. Existing attack methods designed for classical systems fail against QNNs due to
quantum-specific constraints: aggressive downsampling required by limited
qubit resources destroys conventional triggers, while the spectral learning bias of parameterized
quantum circuits (PQCs) restricts learnable patterns. To tackle this, we present HarmQ, a
quantum-native
backdoor attack that exploits PQCs' inherent
Fourier decomposition bias through harmonic trigger patterns. Our approach employs sinusoidal perturbations on coarse grids with block-uniform structure, ensuring survival through downsampling while aligning with PQCs' preference for low-frequency components. This enables effective
backdoor injection under realistic black-box conditions where attackers access only training data. Experiments on MNIST and Fashion-MNIST demonstrate that HarmQ achieves attack success rates exceeding 99% while maintaining over 90% clean accuracy, significantly outperforming existing methods including BadNets (2.77% ASR), Watermark (7.96% ASR), Q-FGSM (44.32% ASR) and QUAP (3.40% ASR). Parametric t-SNE visualizations of
quantum state representations confirm that harmonic triggers create distinctly separated clusters, evidencing HarmQ as a fundamental security threat for QNNs.
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All authors Junrui Zhang, Zemin Chen, Chunsheng Xin, Hongyi Wu, Rui Ning