Mathematical Physics · Cross-listed from math.CO
$k$-Convex Polyominoes by Semi-perimeter
Andrew R. Conway and Anthony J. Guttmann
We give the conjectured solution for the generating function of $k$-convex polyominoes, enumerated by semi-perimeter. The solution was obtained from the analysis of enumeration data that we generated.
High Energy Physics (Phenomenology)
Measuring Ultralight-Axion Coherence with Galaxy Polarization Correlations
Yasuo Doi
Ultralight
axion-like particles coupled to
photons rotate the linear polarization of distant sources. We propose using the three-dimensional two-point correlation of
galaxy polarization-rotation angles to measure not only the amplitude of this birefringence field but also its spatial coherence scale. For a nonrelativistic ALP component with an isotropic Gaussian velocity distribution, the equal-time field correlation has an $e^{-1}$ scale $L_{\rm G}^{\rm phys}=\sqrt{6}/(m_a v_a)$, where $v_a$ is the three-dimensional rms ALP velocity dispersion. A detected turnover in the
galaxy-pair correlation therefore measures the characteristic momentum scale $m_a v_a$, while the correlation amplitude constrains $g_{a\gamma}\sqrt{\Omega_a/\Omega_{\rm DM}}$. For a fiducial survey with $10^6$ polarized
galaxies over a quarter of the sky to $z=2$ and effective per-
galaxy scatter $\sigma_{\rm tot}=10^\circ$, we find $5\sigma$ sensitivity to sub-degree correlated rotations over $m_a(10^{-3}c/v_a)\sim10^{-29}$–$10^{-27}\,{\rm eV}$, with $\sigma[\log_{10}(m_a v_a)]\lesssim0.1$ for detected signals across much of this range. This provides a
geometric late-time probe complementary to CMB birefringence and structure-formation constraints.
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Quantum Physics
Q2NSViz: An Open-source Standalone Visualizer for Quantum Network Simulations
Francesco Mazza, Marcello Caleffi and Angela Sara Cacciapuoti
The unique and non-classical features of
quantum networks make their simulation and intuitive understanding inherently difficult. In this work, we present Q2NSViz, an open-source Python-based visualization tool for replaying and inspecting
quantum-network simulation traces. Q2NSViz reconstructs the time
evolution of the simulated network state, including physical
topology, stored and in-flight
qubits, classical bits and packets, measurements, and
entanglement relationships. In this way, it exposes not only physical connectivity, but also the dynamic
entanglement-induced structure produced, consumed, and transformed by protocol execution. Q2NSViz is built around a decoupled JSON/NDJSON trace contract, a Qt-free replay engine, and an interactive PyQt6 interface, making it a standalone companion to Q2NS and reusable by other simulation backends that emit the same trace format. By turning execution traces into navigable and reproducible visual artifacts, Q2NSViz provides a zero-coding tool for researchers and educators, narrowing the gap between abstract protocol logic and concrete execution.
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Superconductivity
Magnetothermopower and particle-hole symmetry in a cuprate strange metal
Yu-Te Hsu, Matija Čulo, Thom Ottenbros et al. (+6 more)
Here, we report magnetothermopower measurements on overdoped (Bi,Pb)2(Sr,La)2CuO6+delta (Bi2201) single
crystals in
magnetic fields up to 35 T. Whereas the temperature dependence of the zero-field Seebeck coefficient S(T) can be captured using Boltzmann transport theory, the field-dependent response S(H) cannot. Instead, the magnetothermopower contains a large additional contribution whose field and temperature dependence is consistent with the presence of short-range superconducting order well above Tc. Combined with earlier
Hall and magnetoresistance results, these data imply that the overdoped cuprate strange metal contains two transport sectors with distinct particle-hole
symmetry: a conventional particle-hole-asymmetric
Fermi-
liquid (FL) contribution governing the
Hall effect and the zero-field thermopower, and a nearly particle-hole-symmetric sector dominating the anomalous longitudinal magnetotransport. We formulate a phenomenological real-space model in which disconnected FL islands are embedded in a compensated Dirac
liquid of phase-incoherent d-wave Bogoliubov quasiparticles. This picture reconciles conventional zero-field transport with anomalous magnetothermopower and magnetoresistance and offers a concrete framework for thinking about strange
metallicity in overdoped cuprates.
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All authors Yu-Te Hsu, Matija Čulo, Thom Ottenbros, Yingkai Huang, Jake Ayres, Steffen Wiedmann, Mikhail I. Katsnelson, Nigel E. Hussey, Mikhail Titov
Plasma Physics
Radiation reaction measurements via single-shot energy-loss determination in high-intensity laser-electron collisions
Philipp Sikorski and Daniel Seipt
Effects of radiation reaction are considered a key factor for
lasers-
plasma-interactions at ultra-high intensities, and gaining precise understanding of these phenomena will be crucical for discoveries of novel strong-field QED effects. In this paper we investigate an experimental geometry that allows a direct single-shot measurement of radiation reaction energy losses in high-intensity
laser-beam collisions. This is made possible by simultaneous measurements of the pre-collision and post-collision electron beam spectra in a single shot by employing a dedicated 90-degree scattering geometry between the electron beam and the colliding high-power
laser. We discuss the principal requirements and design constraints, e.g. for the electron beam divergence and source size. We derive an analytic expression for the correlation between the final particle energy and the scattering angle. Numerical simulations are performed employing both classical and
stochastic quantum radiation reaction models to predict the experimental outcome and demonstrate the feasibility of the scenario.
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Fluid Dynamics
Emergent coordination and propulsion of a model spherical ciliate
Hang Su, Timothy A Westwood and Eric E Keaveny
A longstanding challenge in biofluid dynamics research is a mechanistic understanding of the coordinated movement of motile cilia and its resulting ability to facilitate fluid transport. In this study, we develop numerical techniques to simultaneously compute the emergent coordination of and propulsion by filamentous model cilia covering the surface of a sphere. To accomplish this, we develop what we refer to as the filament oscillator model, in which each cilium has two dynamic degrees of freedom: a phase variable that maps to a specific shape in a prescribed sequence, and an angle that describes the overall orientation of the sequence. By varying a parameter related to cilium stiffness, we show that there is bistability between
symplectic-like and diaplectic metachronal waves, provided that the stiffness is sufficiently low. Above the critical stiffness, only diaplectic waves emerge. Further, we analyse the propulsive capabilities and flow fields of the two emergent states, showing that diaplectic waves provide more efficient propulsion due to their shorter wavelengths. In addition, we examine how introducing beat-plane tilt leads to ciliate rotation while maintaining nearly identical emergent states and comparable swimming speeds.
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Optics
Structured Optical Fields Reveal Nanoscale Chiral Light-Matter Interactions Governed by Optical Chirality
Atsushi Kamegaya, Shun Hashiyada and Yoshito Y. Tanaka
Optical chirality has been proposed as the local electromagnetic quantity governing
chiral light-matter interactions, yet in conventional circularly polarized fields its magnitude is locked to the electric energy density, obscuring its independent role. Here we create a structured optical field in which optical chirality arises spatially in magnitude and sign while the electric energy density remains nearly uniform. A single
chiral nanoparticle exhibits a differential response that follows this spatial variation, whereas no modulation is observed for an achiral nanoparticle, providing direct experimental evidence that optical chirality governs nanoscale
chiral light-matter interactions. Measurements of wavelength-dependent optical rotation further provide an experimental estimate of the
chiral polarizability, predicting a
chiral gradient force of approximately 100 fN and a one-dimensional trapping potential exceeding the thermal energy at room temperature under optimized aqueous trapping conditions.
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Astrophysics of Galaxies
Bridging the mass gap: Diffuse radio emission in GAMA galaxy groups using EMU and DINGO survey data
Sai Wagh, Tessa Vernstrom, Luke J.M. Davies et al. (+11 more)
Diffuse
radio emission provides a powerful probe of non-thermal processes in the large-scale structure, yet its properties in
galaxy groups remain poorly constrained. Using deep 943 MHz
radio continuum data from the Evolutionary Map of the Universe (EMU) and 1.37 GHz data from the Deep Investigations of Neutral Gas Origins (DINGO) survey, we investigate diffuse
radio emission in 400
galaxy groups selected from the GAMA survey at $z < 0.1$. We employ a multi-resolution filtering technique to suppress compact
radio sources and enhance extended, low-surface-brightness emission associated with the intra group medium. Integrated flux densities are measured within group radii, and background fluctuations are quantified using random control regions. While most systems yield non-detections, we identify 46/400
galaxy groups with candidate diffuse emission, spanning
radio powers of $10^{19}-10^{24}\,\mathrm{W\,Hz^{-1}}$. Stacked measurements reveal a weak positive trend between
radio power and
halo mass. The observed emission levels lie above simple extrapolations of cluster scaling relations, suggesting that different physical processes dominate in the group regime. Additionally,
stellar mass ratios of the most massive
galaxies in the group and Early Type
Galaxy fractions suggest that these
galaxy groups are relatively young, evolving systems where
galaxy interactions and mergers may power the emission. Comparisons with Magneto Hydrodynamical simulations indicate shock acceleration alone cannot explain the observed emission, pointing to an important role for fossil
plasma re-acceleration and group-scale dynamical activity. These results demonstrate diffuse
radio emission is present in a non-negligible fraction of
galaxy groups, providing new constraints on non-thermal processes in low-mass environments.
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All authors Sai Wagh, Tessa Vernstrom, Luke J.M. Davies, Lister Staveley-Smith, Stefan Duchesne, Christopher J. Riseley, Timothy J. Galvin, Franco Vazza, Konstantinos Kolokythas, Andrew M. Hopkins, Jonghwan Rhee, Tobias Westmeier, Pascal Jahan Elahi, Martin Meyer
Quantum Physics
Deterministic Minimum-Leakage Continuous-Variable Quantum Key Distribution with Phase-Conjugated Twin Beams
Zhenlin Zhao and Dawei Wang
Minimum-leakage continuous-variable
quantum key distribution suppresses Eve's Holevo information by engineering the signal ensemble during state preparation. The existing symmetric realization relies on Alice-side heralding. Here we propose an alternative two-mode symmetric realization that is deterministic without heralding. The minimum-leakage condition of the new protocol requires transmitting two phase-conjugated twin beams (PCTB). We show that the PCTB protocol is related to the heralding protocol through a common
entanglement-based source but corresponds to a different prepare-and-measure decomposition. The two protocols attain the same secret key rate per transmitted optical mode in the very-large-squeezing limit. For finite squeezing, however, the PCTB protocol requires approximately 3 dB less squeezing to achieve the same performance. We further optimize mode-symmetric Gaussian two-mode entangling-cloner attacks and find that correlated ancillary modes provide only a limited advantage over independent attacks under the minimum-leakage condition. These results establish phase-conjugated twin beams as a deterministic and experimentally appealing route to symmetric minimum-leakage CV-QKD.
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High Energy Astrophysical Phenomena
Astrophysical Population Coordinates for Supermassive Black Hole Binaries in Pulsar Timing Array Inference
Yikun Li, Muhammad Ahmad, Shaoguang Guo et al. (+1 more)
Pulsar timing arrays can probe the population physics of supermassive black-hole binaries through the nanohertz gravitational-wave background. We construct a phenomenological forward model that follows source abundance, binary residence time, the high-mass population, finite-source strain moments, and the
pulsar timing response. The simulated observables constrain three standardized population coordinates: $\beta$, which controls the residence-time and spectral response; $\phi_{eff}$, which describes source normalization after accounting for its covariance with $\beta$; and $m_{eff}$, which is dominated by the high-mass cutoff. In the evaluation ensemble, the posterior-mean correlations with the simulated values are $0.928$, $0.926$, and $0.884$, with central 90 per cent coverages of $0.938\pm0.015$, $0.871\pm0.021$, and $0.898\pm0.019$, respectively. Frequency-resolved observables are most important for $\beta$, and strain moments beyond a common-process power law provide sensitivity to the normalization and high-mass coordinates; the fourth strain moment identifies $m_{eff}$ with rare, massive binaries. These coordinates quantify the relative sensitivity of the adopted PTA summaries within this population model, for which nearby population realizations retain substantial posterior overlap.
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All authors Yikun Li, Muhammad Ahmad, Shaoguang Guo, Lang Cui
Instrumentation and Methods for Astrophysics
The Lightspeed project: high-speed, ultra-low read noise imaging and polarimetry for the Magellan telescopes
Christopher Layden, Kevin Burdge, John J. Piotrowski et al. (+12 more)
Lightspeed will be an ultra-fast (> kHz), ultra-low read noise, multicolor (ugriz + IR) imager for the 6.5 meter Magellan Clay
telescope. In a single-channel configuration, Lightspeed will also enable single-shot linear polarimetry, narrowband imaging, or white-light imaging. Lightspeed is designed around groundbreaking single-
photon-resolving detector technologies: deep sub-electron read noise CMOS image sensors from Fairchild Imaging and a HgCdTe avalanche photodiode array from Leonardo. Here we present Lightspeed's basic optical design concept, predict its on-sky performance, and highlight science cases that Lightspeed has the potential to revolutionize. Lightspeed builds upon the success of proto-Lightspeed, a single-channel prototype employing commercial-off-the-shelf re-imaging optics. proto-Lightspeed is now available as a PI instrument on the Clay
telescope. We also discuss the current status of proto-Lightspeed and lessons learned from its commissioning, applicable to the development of Lightspeed and any other instrument seeking to integrate scientific CMOS image sensors.
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All authors Christopher Layden, Kevin Burdge, John J. Piotrowski, Gabor Furesz, Juliana Garcia-Mejia, Jack Dinsmore, Roger W. Romani, David Osip, Geoffrey Mo, Vera Berger, Aaron Householder, Danielle Frostig, Emma T. Chickles, Emma Pellecer, Malina Desai
Cosmology and Nongalactic Astrophysics
Ricci Focusing Degeneracy between Dynamical Dark Energy and Matter Inhomogeneity
I. A. Moiseev and O. S. Sazhina
The influence of dynamical (phantom) dark energy on light propagation within the framework of the Zeldovich-Kantowsky-Dyer-Roeder (ZKDR) approximation is discussed. This effect is considered in terms of the
redshift-dependent parameter $\alpha(z)$ of the ZKDR model, which is defined as the ratio of the mean matter density (baryonic matter, dark matter, and dark energy in the form of a cosmological constant) to the total density, including its fluctuations. We demonstrate that the observational manifestations of $\alpha(z)$ admit two equivalent interpretations in the framework of both (1) a dynamical dark energy model, and (2) a model considering weak gravitational
lensing in a universe with a cosmological constant. Thus, a degeneracy arises between these two physical scenarios. Finally, a simple statistical test, independent of cosmological probes, is proposed for breaking this degeneracy and testing the dynamical nature of dark energy. The test is based on the expected isotropy of dynamical dark energy at a fixed
redshift, in contrast to
stochastic inhomogeneities in the matter distribution induced by weak gravitational
lensing.
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Materials Science
Quantized Photocurrents in Gapless Topological Matter
Byunghoon Kim, Tenzin Norden, Mohammad Yahyavi et al. (+17 more)
The
quantum Hall effect establishes that
topology can fix a material response to integer multiples of fundamental constants when an energy gap isolates the relevant
symmetry-protected electronic states. Whether such universal quantization can also emerge in gapless matter, where topological bands coexist with a continuum of metallic excitations, has remained a fundamental question in the field of
quantum materials.
Chiral topological semimetals provide a unique setting in which to explore this principle; when optical transitions are confined to a single
chiral node, the resulting circular photogalvanic effect is predicted to be quantized by the topological charge of the node. In real materials, however, this nonlinear optical phenomenon has remained experimentally elusive, obscured by trivial band transitions, insufficient energy separation between node pairs, and their relative positions with respect to the
Fermi level. Here we observe a quantized circular photogalvanic effect in the
chiral topological semimetal Rh0.95Ni0.05Si. Band engineering via Ni substitution opens a
photon-energy window dominated by interband optical transitions at the {\Gamma}-point multifold node. This allows circularly polarized near- to mid-infrared pulses to drive a helicity-odd terahertz response that manifests three hallmarks of quantization: a sharp onset, a
photon-energy-independent plateau governed by the magnitude of the monopole charge, and an abrupt long-wavelength cutoff imposed by Pauli blocking. Our work thus establishes an all-optical analogue of the
quantum Hall effect and a new paradigm to realize topological quantization in gapless matter.
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All authors Byunghoon Kim, Tenzin Norden, Mohammad Yahyavi, Kaustuv Manna, Tyler A. Cochran, Zi-Jia Cheng, Xian P. Yang, Yu-Xiao Jiang, Xiangyu Luo, Payman Kazemikhah, Areeq Hasan, Vladimir N. Strocov, Sergey Shilov, Ilya Belopolski, Claudia Felser, Md Shafayat Hossain, Rohit P. Prasankumar, Guoqing Chang, M. Zahid Hasan, Prashant Padmanabhan
Strongly Correlated Electrons
Fractionalized Fermi liquids with the ghost-Gutzwiller Ansatz
Ivan Pasqua, Carlos Mejuto-Zaera and Michele Fabrizio
Fractionalized
Fermi liquids ($\mathrm{FL}^{\!*}$), elusive metallic states characterized by fractionalized quasiparticles alongside conventional ones and defying Luttinger's
theorem, are
prime candidates for the pseudogap regime of underdoped cuprates. We show that a $\mathrm{FL}^{\!*}$ phase emerges in the single-band $t$-$J$ model through a simple ghost-Gutzwiller Ansatz, optimized at the cost of a mean-field calculation. The resulting temperature-doping phase diagram encompasses a low-doping $\mathrm{FL}^{\!*}$, a $d$-wave superconducting dome, and an overdoped conventional
Fermi liquid, thereby reproducing key qualitative features of cuprate phenomenology.
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Soft Condensed Matter
Tunable Signal Penetration and Response Plateaus in Bistable Mechanical Media
Sven Pattloch and Joachim Dzubiella
Dynamic processing of mechanical signals is crucial for soft robotics and mechanosensing, yet classical viscoelastic materials lack intrinsic tunability and quantitative design rules. We show that internal bistability provides a simple but powerful mechanism to tailor response and signal attenuation in mechanical (meta)materials. In our model, bistable elements switch discretely with an intrinsic timescale between states that differ in potential energy $\epsilon$,
equilibrium length $\Delta l$, and spring constant $\Delta k$. We combine Brownian dynamics simulations with discrete Poisson switching at rate $\nu$ and a nonlinear continuum (field) theory for the macroscopic strain relaxation. The model yields closed-form solutions for the linear response and the spatial penetration depth, revealing two complementary phenomena: a universal screening mechanism (akin to the electrostatic `skin effect') that strongly reduces signal penetration when the driving frequency exceeds the internal relaxation rate, and a frequency-insensitive response plateau arising from timescale separation. The attenuation strength, expressed by a screening length, is controlled primarily by the conformational length change $\Delta l$, while the attenuation regime and plateau position are tuneable via $\nu$. A parameter study exposes a fundamental design trade-off: larger $\Delta l$ strengthen dissipation but also raise the elastic energy barrier for state transitions, eventually causing state-locking where damping vanishes. Optimal attenuation thus emerges from a compromise between pronounced bistability and a surmountable barrier. Owing to its analytical tractability and generic formulation, our framework yields explicit design rules applicable to systems from biopolymers to synthetic catch bonds and metamaterials, enabling the design of soft materials with frequency-selective mechanical response.
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Adaptation and Self-Organizing Systems · Cross-listed from cs.NE
Structured Fluctuations and the Information Dynamics of Self-Maintenance in Growing Neural Cellular Automata
Atsushi Masumori, Hiroki Sato and Takashi Ikegami
Growing Neural Cellular Automata (GNCA) are capable of robust self-maintenance and self-repair, yet the internal dynamical mechanisms that support these capabilities remain poorly understood. Here, we investigate the role of internal fluctuations–temporal micro-variability of hidden channel states–in a trained GNCA model, challenging the assumption that such variability is merely residual
stochastic noise. Through systematic analysis spanning update-rate sweeps, spatial correlation measurements, dimensionality reduction of collective state trajectories, localized damage experiments, transfer
entropy vector field estimation, and partial information decomposition, we show that internal fluctuations are spatially structured, dynamically coupled to an attracting collective state, and associated with distributed small-magnitude updates that contribute to damage recovery. Damage induces a global deviation in latent state space followed by gradual re-convergence, and suppressing distributed small-magnitude updates associated with baseline fluctuation dynamics outside a permissive radius that encompasses the majority of the
cells significantly impairs recovery. Transfer
entropy analysis characterizes a spatially differentiated repair response: corrective inward flow near the damage site coexists with outward perturbation propagation at greater distances. Partial information decomposition further suggests a regime shift from synergy-dominant resting computation to redundancy-increased coordination during recovery. These findings indicate that GNCA self-repair emerges from high-dimensional nonlinear collective dynamics in which internal fluctuations serve as a functional component supporting information flow, coordination, and return toward an attracting recurrent state.
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Superconductivity
Interlayer Phase Locking and Sliding Select Topological Melting Channels in Superconducting Bilayers
Yicheng Zhong and Yi Zhou
Topological transitions in coupled superconducting layers are intertwined: an elementary
vortex in one layer carries both common and relative phase winding. We study a Josephson-coupled
bilayer in an in-plane
magnetic field using renormalization-group analysis and Monte Carlo simulations of the compact layer phases. The field drives Pokrovsky–Talapov (PT) entry of interlayer
solitons, and free-energy calculations in fixed
soliton sectors show PT square-root scaling over the sampled densities at finite temperature. Interlayer phase locking and sliding then select distinct Berezinskii–Kosterlitz–Thouless (BKT)-like melting channels. The locked commensurate phase melts through same-vorticity layer pairs when the
geometric-mean common helicity modulus $\Upsilon_{+,g}$ reaches $T/(2\pi)$, with layer correlation exponent $\eta_l=1/4$. A stable sliding incommensurate phase melts through elementary layer
vortices on a line of BKT fixed points, where $\Upsilon_{+,g}+\Upsilon_{-,g}=2T/\pi$ and $\eta_l$ is set by the ratio of the relative and common
moduli. When the relative helicity modulus is identified with the relative-phase stiffness, our simulations agree with this prediction, and the common superfluid stiffness at incommensurate melting is nearly twice its value at commensurate melting. Near
soliton entry, however, the dilute sliding state is unstable to opposite-vorticity layer pairs. Our results connect PT
soliton entry with field-tunable BKT-like melting and identify the pair-stability condition that links them.
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Instrumentation and Methods for Astrophysics
Demystifying image-recovery from radio interferometers: toward a multiscale predictive model
Dan Miao and Guang-Xing Li
Radio interferometers suffer from the missing short-spacing problem, losing large-scale diffuse emission. This missing flux underestimates gas mass and biases key metrics like
star formation efficiency. Quantifying this scale-dependent loss currently relies on computationally intensive mock observations, lacking an analytical image-domain framework. We introduce the Constrained
Diffusion Decomposition (CDD) method to decompose an input image ($I_{\mathrm{in}}$) into $n$ continuous scale-space components, denoted as $I_l = \mathrm{CDD}_l(I_{\mathrm{in}})$ for $l \in [1, n]$, and apply it to simulated Atacama Large Millimeter/submillimeter Array (ALMA) observations of the Perseus molecular cloud across multiple array configurations. We find that the interferometric spatial filtering response can be mathematically decoupled: the scale-dependent flux recovery fraction follows a one-dimensional error function (erf), defined as $R(l) = \frac{B}{2} \left[ 1 - \mathrm{erf}\left( \frac{l - c_{\mathrm{recover}}}{w} \right) \right]$, where compact structures are effectively recovered, while extended emission decays monotonically as scales approach the maximum recoverable scale. The proposed CDD–erf framework predicts the spatially filtered interferometric image $I_{\mathrm{pred}}$ directly in the image domain, bypassing visibility simulations, mapping the true sky brightness distribution via the equation $I_{\mathrm{pred}} = \sum_{l=1}^{n} [ \mathrm{CDD}_l(I_{\mathrm{in}}) \times R(l)]$. This provides a quantitative bridge between model and interferometric observations.
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Superconductivity
Systematic modulation of superconducting gap dynamics in YBCO|BNT|YBCO Josephson Junctions through THz field interaction and BNT ferroelectric barrier
Sukhanidhan Singh, Muthukkumaran Karthikeyan, Geoffrey Chanda et al. (+5 more)
The integration of ferroelectric barriers into high-temperature Josephson junctions offers a pathway to tunable superconducting
quantum devices. Here, we demonstrate robust Josephson coupling in YBa2Cu3O7-x (YBCO)/Bi0.5Na0.5TiO3 (BNT)/YBCO trilayer junctions incorporating a 40 nm ferroelectric BNT barrier. Epitaxial trilayers were fabricated by pulsed
laser deposition on SrTiO3 substrates and investigated under broadband terahertz (THz) irradiation (0.5-2.5 THz). At 1.5 THz, close to the Josephson
plasma resonance, the BNT polarization increased from 33.4 to 46.4 uC/cm2 at 30 K, enhancing superconducting transport. The junctions exhibited a well-defined zero-voltage supercurrent branch, with the critical current Ic(T) remaining nearly constant up to 60 K and reaching 468.2 uA under 1.5 THz excitation, evidencing strong phase coherence. Scanning tunneling spectroscopy revealed an enhanced superconducting gap in YBCO/BNT/YBCO (Delta = 1.3 meV) compared with pure YBCO (Delta = 1.05 meV), while optical conductivity measurements showed a reduction in conductivity and gap with increasing temperature, consistent with BCS theory under THz excitation. Atomic force microscopy and X-ray reflectivity confirmed uniform morphology and sharp interfaces, excluding defect-mediated transport.
Magnetic field modulation of Ic(B) exhibited a canonical Fraunhofer interference pattern, and resistance mapping revealed alternating lobes of high and low dissipation, indicating coherent Josephson tunneling. These results establish that Josephson coupling is intrinsic to the YBCO/BNT/YBCO junctions, enabled by the dipolar character and dynamic THz response of the BNT barrier. This study identifies BNT as a viable, tunable barrier material for next-generation high-Tc superconducting
quantum devices.
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All authors Sukhanidhan Singh, Muthukkumaran Karthikeyan, Geoffrey Chanda, Thanayut Kaewmaraya, Pairot Moontragoon, Guoxing Sun, Zongjin Li, Anucha Watcharapasorn
Materials Science
Magnetic Contributions to Phase Stability in the Co-Ni Binary: A First-Principles CALPHAD Study
Prajna Jalagam, Zhigang Wu, John Lawson et al. (+1 more)
We propose a simple method to employ ab-initio calculations to determine
magnetic contributions to free energy of
alloys. Validation on the Co-Ni binary demonstrates that this ab initio approach reproduces experimental FCC-HCP phase
equilibria while providing physically transparent, structure-dependent
magnetic parameters suitable for multicomponent extrapolation. Our results demonstrate that physically grounded
magnetic parametrization, derived directly from electronic structure calculations, enables predictive phase diagram modeling for
magnetic alloy systems.
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All authors Prajna Jalagam, Zhigang Wu, John Lawson, Axel van de Walle
Strongly Correlated Electrons
Measurement-induced phase transition in space
Jia-Qiang Li, Liang-Jun Zhai, Shuo Liu et al. (+1 more)
Measurement-induced phase transitions (MIPTs) in monitored
quantum circuits are usually characterized by preparing steady states at different uniform measurement probabilities. Here we introduce a spatial realization of the MIPT by imposing a deterministic measurement gradient in a single monitored Clifford chain. The resulting steady state contains coexisting volume-law, critical, and area-law regions, with the point $p(x)=p_c$ acting as a spatial critical cut. By scanning
entanglement observables across this profile, we show that the transition is organized by a spatial scaling form. Although this structure is analogous to finite-time scaling in temporally driven MIPT, the spatial protocol has no Kibble-Zurek dynamics. Instead, the physical bounds $0\le p\le 1$ impose a finite linear window, producing cutoff-controlled asymptotic regimes whose fitted exponents provide direct access to the correlation-length exponent $\nu$. Our results establish spatially inhomogeneous measurements as a controlled route to engineer and probe measurement-induced criticality within a single steady state.
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All authors Jia-Qiang Li, Liang-Jun Zhai, Shuo Liu, Shuai Yin
Astrophysics of Galaxies
A FLASH HI absorption search in compact sources in the pilot ASKAP interplanetary scintillation field
Paris E. Gordon-Hall, Emily F. Kerrison, Elizabeth K. Mahony et al. (+13 more)
In this pilot study, we use data from the First Large Absorption Survey in HI (FLASH) to search for redshifted HI 21cm absorption at $0.4<z<1$ towards 157 bright
radio sources with Interplanetary Scintillation (IPS) measurements at 820MHz in a single field observed with the Australian Square Kilometre Array Pathfinder (ASKAP)
radio telescope. The ASKAP IPS measurements, which use only 2.5 minutes of observing time in total, allow us to estimate the compactness of these
radio sources on sub-arcsecond scales at a frequency within the 712-1000MHz FLASH band. In particular, the Normalised Scintillation Index (NSI) for each source reflects the fraction of the flux density arising from compact components less than 0.1 arcsec in diameter. We find that $18\pm5$% of ASKAP sources with flux densities above 150mJy are highly compact with NSI $\geq0.8$ - implying that at least 80% of their
radio emission arises from a single region smaller than about 800pc in size. The compactness of these sources makes them ideal probes for an HI absorption search, since the covering factor for any HI gas clouds along the line of sight is likely to be high. About half of the sources with NSI $\geq0.8$ also have peaked
radio spectral energy distributions (SEDs), consistent with previous IPS studies at lower frequencies. These pilot results imply that IPS measurements with ASKAP can provide a simple and powerful tool for identifying uniform samples of compact
radio sources at frequencies of a few hundred MHz across large areas of sky. With FLASH, we detect two new HI absorption lines against compact sources in the $\sim30$deg$^2$ region of sky covered by the IPS data; an associated HI line at
redshift $z=0.9540$ (with a matching optical
redshift) in MRC 2125-237 (NSI = 0.98), and a likely intervening line at $z=0.4632$ towards MRC 2131-241 (NSI = 0.84).
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All authors Paris E. Gordon-Hall, Emily F. Kerrison, Elizabeth K. Mahony, Elaine M. Sadler, Hyein Yoon, J.N.H.S. Aditya, James R. Allison, Rajan Chhetri, Ron Ekers, Marcin Glowacki, John Morgan, Vanessa A. Moss, William Roster, Mara Salvato, Renzhi Su, Matthew Whiting
High Energy Physics (Theory)
Non-Abelian $A_4$ vortices in $SO(3)$ gauge theory and non-invertible symmetries
Yoshihiko Abe, Tetsutaro Higaki, Kazuya Murakami et al. (+2 more)
We construct finite-tension non-Abelian
vortex solutions in a renormalizable $(3+1)$-dimensional $SO(3)$ gauge theory Higgsed to the tetrahedral group $A_4$ by a
Higgs field in the
spin-3 representation. Since the
vacuum manifold is $SO(3)/A_4$, the
vortices are characterized by the non-Abelian fundamental group $\pi_1(SO(3)/A_4)\simeq \widetilde{A}_4$, the binary tetrahedral group. We obtain explicit axisymmetric
vortex solutions carrying holonomies corresponding to the order-two and order-three conjugacy classes of $A_4$, determine their tensions numerically, and show that they exhibit type-I, type-II, and Bogomol'nyi–Prasad–Sommerfield-like behavior depending on the
Higgs and gauge
boson mass ratios. The
vortices are classified by conjugacy classes of $\widetilde{A}_4$, while their infrared descriptions are labeled by conjugacy classes of $A_4$. We further demonstrate that the smooth finite-tension
vortices reduce in the infrared to Gukov–Witten surface operators of the $A_4$ discrete gauge theory, thereby establishing a finite-energy ultraviolet completion of non-invertible defects in a renormalizable gauge-
Higgs theory.
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All authors Yoshihiko Abe, Tetsutaro Higaki, Kazuya Murakami, Muneto Nitta, Ryo Yokokura
Astrophysics of Galaxies
Environmental Imprints on the Assembly of the Cool Gas around Bright Cluster Galaxies
Runyu Zhu, Hu Zou, Taotao Fang et al. (+14 more)
Galaxy clusters represent extreme
cosmic laboratories where environmental processes dramatically reshape their constituent
galaxies, yet their effect on the gaseous
halos of central
galaxies remains poorly constrained. Here we present the first statistical mapping of cool gas around massive brightest cluster
galaxies (BCGs) at $z\approx0.55$. Using Mg II absorption in stacked sight-line spectra from over a million background
quasars observed by the Dark Energy Spectroscopic Instrument, we compare BCGs to a matched sample of field
galaxies and trace the radial profile from 40 kpc to 15 Mpc. Our analysis reveals a striking dual environmental signature: within 200 kpc, the circumgalactic medium (CGM) around BCGs is significantly suppressed compared to that of field
galaxies, while at larger radii (200 kpc to 10 Mpc) a pronounced excess of cool gas emerges. This clear transition from suppression in the core to enhancement on such large scales delineates a novel observed pattern for gas regulation by the dense environment. It suggests that clusters may not only strip gas in the core but also facilitate its accumulation in the outskirts. Our results provide key observational constraints on theoretical models of environmental processing in and around the most massive dark matter
halos.
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All authors Runyu Zhu, Hu Zou, Taotao Fang, Enci Wang, Zeyu Chen, Zhaobin Chen, Weiyu Ding, Jinfu Gou, Weijian Guo, Niu Li, Wenxiong Li, Shufei Liu, Haoming Song, Jipeng Sui, Xi Tan, Yunao Xiao, Jingyi Zhang
Statistical Mechanics
A Gaussian-Remainder Hierarchy for Sums of Random Variables with Big-Jump Statistics
Stanislav Burov
We develop an exact Gaussian-remainder hierarchy for the probability density of the sum of $N$ independent, identically distributed random variables with broad, finite-variance distribution for the summands. The hierarchy separates the Gaussian fixed-point contribution from residual sectors that retain the original single-summand density. For subexponential densities, the first nontrivial truncation yields a simple finite-$N$ approximation that involves one convolution with a Gaussian background and a subtraction that removes Gaussian overcounting. This approximation captures the Gaussian center, the crossover region, and the big-jump tail within a single expression, as demonstrated numerically for stretched-exponential and finite-variance power-law examples. The same first-order approximation reproduces the known asymptotic anomalous rate function for sums of stretched-exponential random variables and also provides an accurate approximation to the corresponding finite-$N$ rate function.
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Statistical Mechanics
From stable periodic orbits to many-body chaos: doubly tunable prethermalization via engineering of an emergent band structure
Jianan Wang, Yang Hou, Andrea Pizzi et al. (+3 more)
We uncover a family of many-body periodic orbits in a periodically driven (Floquet)
spin system away from the high-frequency limit. While linear stability analysis predicts that perturbed many-body trajectories remain close to stable periodic orbits, thermodynamic principles dictate that Floquet heating will ultimately set in. Our work aims to resolve the tension between these two expectations. In particular, we show that perturbations away from the stable periodic orbits feature a description akin to a quasiparticle band structure. A long-lived prethermal regime appears when modes around the gapless point are slowly populated. The dispersion determines the prethermal lifetime, and we show how band engineering leads to a "doubly tunable" parametric dependence of the prethermal lifetime $R^{-W}$, with $R$ the width in momentum space of the quasiparticle distribution and $W$ the exponent of the dispersion around the gapless point. Our results not only establish a powerful route toward stabilizing non-
equilibrium phases of matter in driven many-body systems but also establish a conceptual bridge between periodic orbits in 'low-dimensional' nonlinear systems and many-body chaos.
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All authors Jianan Wang, Yang Hou, Andrea Pizzi, Johannes Knolle, Roderich Moessner, Hongzheng Zhao
Mesoscale and Nanoscale Physics
Domain wall motion in ferromagnetic nanowires driven by a localized Gaussian thermal gradient
M. A. Jafar Pikul, M. A. S. Akanda and M. T. Islam
We investigate
magnetic domain wall (DW) dynamics in a uniaxial
ferromagnetic nanowire under the localized Gaussian temperature profile of a
laser spot using the
stochastic Landau-Lifshitz-Gilbert equation. The DW velocity increases linearly with peak
laser temperature and decreases with increasing
laser to DW distance. The velocity varies nonlinearly with Gilbert damping because damping strengthens thermal
magnon excitation but shortens the
magnon propagation length. The DW initially lies away from the
laser-heated region, so the temperature gradient at its position is effectively zero and the entropic torque is negligible. The DW motion is therefore mainly driven by magnonic
spin-transfer torque. We analyze
laser temperature,
laser to DW distance, damping, uniaxial anisotropy, and
laser width. The analysis shows that
laser width and
laser to DW distance independently control the DW response. These findings may clarify the mechanism of localized thermally driven DW motion and guide thermal control strategies in spintronic racetrack-
memory devices.
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Quantum Physics
Parallel Hadamard Test
Soichiro Imamura and Synge Todo
The Hadamard test is a fundamental building block widely used in many
quantum computing
algorithms. It estimates the real or imaginary part of $\langle \psi \vert U \vert \psi \rangle$, where $\vert \psi \rangle$ is a
quantum state and $U$ is a
unitary operator. In many
algorithms, however, many such quantities must be estimated, leading to a large number of distinct
circuit types, long computational times, and high financial costs. In this work, we propose the parallel Hadamard test, which combines multiple Hadamard tests into a single
circuit type. We demonstrate how the parallel Hadamard test applies to three structural classes of workloads: arbitrary sets of
unitary operators, prefix-product arrays, and Gram-
matrix elements. For each class, we compare the cost of the parallel Hadamard test with that of the conventional one. Our unified approach significantly reduces the number of distinct
circuit types, and can lower both computational time and financial costs in regimes where fixed per-
circuit overheads dominate the total cost. In Gram-
matrix workloads, it can also reduce the total number of shots when typical off-diagonal overlaps are small.
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Applied Physics
Space-Time Modulated vs 2-Bit Reflect-Arrays: A Comparison of Main Beam Gain and Sidelobe Level Performance
Muhammad Rizwan Akram and Douglas H. Werner
This paper presents a comprehensive analysis of the phase errors introduced by 2-bit reflectarray architectures and investigates their impact on aperture synthesis for beam-steering applications. Building upon this analysis, an amplitude-aware synthesis technique based on space-time modulated (STM) reflect-arrays is proposed to mitigate the main-beam gain degradation commonly associated with STM-based equivalent phase generation while preserving the enhanced phase resolution enabled by temporal coding. A 10{\lambda}by 10{\lambda} reflect-array aperture with {\lambda}/2 inter-element spacing is considered, where the desired aperture phase distribution is synthesized using a library of achievable reflection coefficients generated from all possible combinations of four 2-bit phase states distributed across (L) temporal segments. The proposed approach introduces a phase-tolerance window and selects the reflection state with the highest reflectance within the allowable phase range. By exploiting the inherent amplitude diversity of the STM state space, the proposed approach maximizes aperture efficiency while maintaining the desired beam-steering phase distribution. Numerical results demonstrate that the method substantially reduces the gain penalty typically associated with STM reflect-arrays along with providing significant sidelobe suppression.
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Pattern Formation and Solitons
Eigenvalue-Based Approach to Manipulate and Reconstruct Nonlinear Pulses: Towards Soliton Tomography
Sergey Dremov, Rustam Mullyadzhanov and Andrey Gelash
Soliton content of nonlinear pulses of different physical nature is universally characterized by a discrete set of
eigenvalues. In an ideal channel governed by the nonlinear Schrodinger equation, the
eigenvalues do not change along the wave field propagation. Perturbations leave predictable fingerprints on the
eigenvalue portrait, which was recently used to manipulate optical fiber
solitons in [Phys. Rev. Lett. 134, 193804, 2025]. Here, we develop a theoretical framework to manipulate and reconstruct sech-shaped nonlinear wave fields based on
soliton eigenvalue response functions and the corresponding inverse problem. We derive analytical expressions to enable nonlinear manipulation of
solitons by applying instant, controllable perturbations. Then we present a concept of perturbation sensing with the key feature of nonlinear propagation of the probe signal over an unknown distance, enabling the extraction of information about the perturbation source hidden within nonlinear media or materials. We introduce an integral equation for the inverse problem of reconstructing the unknown shape of the wave field distortions, when the known observational data is a function of deviations in
soliton eigenvalues measured at the end of the nonlinear propagation channel. We evaluate different reconstruction regimes and demonstrate a reliable inverse problem solution in presence of noise, paving the way towards
soliton tomography.
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