Quantum Physics
Fractalizing spacetime: Floquet codes with fractonic excitations that are immobile in space and time
Juliette Soule and Dominic J. Williamson
We generalize fractalization, a procedure for the construction of fracton models, from space to spacetime. We apply spacetime fractalization to construct fracton floquet codes with syndrome excitations that have limited mobility in space and time. This extends the notion of fracton order to intrinsically dynamical
quantum phases of matter that are inequivalent to static fracton phases. We find spacetime type-II fracton floquet codes which have no topological excitations that are mobile in space or time. These codes exhibit an extreme form of
quantum discrete time
crystal order with response periods that scale exponentially in their linear system sizes. In this context, the no-strings rule that characterizes type-II fractons leads to a superlinear scaling of the floquet code fault-distance with time, potentially lowering the time overhead required for
quantum error correction.
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Astrophysics of Galaxies
Rapid Growth of Intermediate-Mass Black Holes through Disk-induced Stellar Disruptions
Mengye Wang, Yiqiu Ma, Qingwen Wu et al. (+3 more)
Dense
nuclear star clusters provide unique environments for studying the dynamical interactions between
stars and massive black holes. When an
accretion disk is present, dissipative
star–disk interactions can capture surrounding
stars, drive their inward migration, and ultimately lead to disk-induced
tidal disruption events\,(dTDEs). The long-term feeding rate from this process, however, cannot be inferred from single-orbit migration estimates alone, as it depends on the coupled
evolution of disk capture, collisional relaxation,
stellar depletion and replenishment, and physical mergers within the
star cluster. In this work, we use high-performance direct $N$-body simulations combined with analytic prescriptions for
star–disk interactions to follow this coupled
evolution for intermediate-mass black holes\,(IMBHs) with
accretion disks embedded in dense
stellar clusters. The simulations track the formation of the
stellar cusp, the capture of
stars by repeated disk crossings, their subsequent orbital damping and migration, and their eventual consumption by the central IMBH. We find that dTDEs can sustain
stellar mass supply rates of $\sim10^{-3}\,M_\odot \,\mathrm{yr}^{-1}$, which exceeds the Eddington-limited gas
accretion rate for IMBHs with $M_\bullet<10^5\,M_\odot$. These results identify dTDEs as an efficient
stellar feeding channel for IMBHs in gas-rich dense
stellar systems. As one possible application, this mechanism may help transform $\sim10^3\,M_\odot$ IMBHs into more massive black-hole seeds, provided that compact
stellar clusters and
accretion disks persist for $>30$ Myr.
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All authors Mengye Wang, Yiqiu Ma, Qingwen Wu, Boyuan Liu, Zijian Wang, Zhili Wang
Soft Condensed Matter · Cross-listed from q-bio.CB
Modeling Tissue Detachment and Rupture Using an Extended Vertex Model with T2-inverse Transitions
Shota Nishimoto and Yuichi Togashi
The vertex model is widely used to describe the mechanics of epithelial tissues, but its conventional formulation assumes that all
cells remain tightly packed and always share edges with their neighbors, making it difficult to represent local detachment or gap formation. Here, we propose a minimal extension of the vertex model that enables
cell detachment by introducing a new topological transformation, T2-inverse, which acts as the inverse of the classical T2 transition. When the imbalance of forces acting on a vertex, quantified by a tension metric $T$, exceeds a threshold, the T2-inverse splits the vertex into multiple vertices and creates a closed polygon that is incorporated as a pseudo-
cell. This operation allows the model to represent the emergence and propagation of local detachment events. Using this framework, we simulate the stretching of a
cell sheet and show that force-induced local detachments can accumulate to produce macroscopic tissue rupture. These results demonstrate that the proposed model extends the capability of the vertex model to describe tissue-level breakdown processes, including detachment and tearing, and provides a foundation for studying a broader class of epithelial mechanical phenomena.
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Strongly Correlated Electrons
Hidden Magnetic Octupolar Order driven by Spin-Orbit coupling in KFeF$_3$
C. A. Crawford, C. I. Hiley, N. C. Bristowe et al. (+6 more)
Phase transitions are typically driven by
symmetry-breaking structural distortions that lift electronic degeneracies, yet in some cases, these transitions may be driven by a hidden order without conventional structural signatures. Here, we demonstrate that the 3$d$ perovskite, KFeF$_3$, hosts such a hidden instability. Using a combination of high-resolution powder diffraction, magnetometry,
symmetry-based analysis and first principles calculations, we reveal that while the 90 K cubic to rhombohedral transition arises from conventional magnetostriction accompanying
antiferromagnetic order, a second transition at 40 K lowers the
symmetry to monoclinic without any detectable Jahn-Teller distortion or translational
symmetry-breaking.
Symmetry-based Landau analysis supports a hidden zone centered
magnetic octupole order parameter, whose improper coupling accounts for the weak ferromagnetism and pronounced
symmetry-breaking strain. Density functional calculations show that
spin-orbit coupling suppresses the competing Jahn-Teller instability, and thereby favors higher rank
magnetic multipolar degrees of freedom. These findings establish KFeF$_3$ as a model system in which the competing energy scales between
spin-orbit coupling and orbital degeneracy result in the emergence of hidden, multipolar order. We show that the control of such
magnetic, multipolar order could, in principle, provide a route to induce altermagnetism.
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All authors C. A. Crawford, C. I. Hiley, N. C. Bristowe, C. Stock, J. Gainza, C. Ritter, M. R. Lees, R. I. Walton, M. S. Senn
General Relativity and Quantum Cosmology
Long-lived ringing of Bronnikov–Kim brane-world black holes and wormholes
Milena Skvortsova
Massive-field perturbations on black-hole and wormhole backgrounds can form long-lived quasinormal ringing; this behaviour is not confined to brane-world spacetimes, but it is also not universal across compact-object geometries. Recent work on a brane-world black hole reported an unusual limiting behaviour in which the real oscillation frequency tends to zero as the scalar mass grows. We test how general this phenomenon is in the Bronnikov–Kim effective brane-world geometries, treating both the black-hole and wormhole sides of the same families. The comparison uses two complementary numerical treatments: Leaver's continued-fraction method for the black-hole side, after reducing the wave equation for the second Bronnikov–Kim family to rational form, and Chebyshev pseudospectral collocation for regular wormhole throats. The black hole of the second Bronnikov–Kim family shows the standard quasi-resonant pattern: the damping rates of the scalar branches considered here become very small, but the real frequencies remain finite. Representative wormholes from the first and second Bronnikov–Kim families also develop increasingly long-lived massive scalar modes, and extending the second-family wormhole scan to larger field mass reduces the damping by more than a factor of four relative to the massless case. Thus the robust brane-world effect found here is the appearance of long-lived massive-field ringing in both black holes and wormholes, whereas the vanishing of the real frequency is metric- or branch-dependent.
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Mesoscale and Nanoscale Physics
Weak-coupling theory of half-metals and other fractional metallic phases in biased doped Bernal bilayer graphene
D. V. Zhitov, A. V. Rozhkov, A. O. Sboychakov et al. (+1 more)
The paper presents a theoretical study of many-body electronic phases in doped and electrically biased Bernal-stacked (AB)
bilayer graphene. We develop a variational mean-field theory with no fitted parameters. For the electron-electron interaction, we employ a parameter-free random-phase approximation to model the short-range screened Coulomb repulsion. The remaining long-range Coulomb potential energy is dictated by the geometry of the sample, behaving as a parallel-plate capacitor. We formulate the theory directly in terms of the experimentally controlled displacement field $\frak D$ rather than the interaction-renormalized interlayer potential difference. It makes our theory better suited for direct comparison with experiment. The resulting phase diagram is quite rich. It hosts several fractional-metal states connected by first- and second-order transitions. At higher bias and doping, three distinct fractional metallic states emerge. We classify these phases by the number of doped sectors and the
symmetry of the order parameters. Our results - obtained without any parameter fitting - reproduce key qualitative and quantitative features of recent experiments. This includes the energy scale associated with the loss of fractional metallic order. At lower bias and doping, the model stabilizes a broad spectrum of fractional-metal phases with more exotic
symmetry-breaking patterns. This suggests that further experimental exploration of the latter regime is warranted.
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All authors D. V. Zhitov, A. V. Rozhkov, A. O. Sboychakov, A. L. Rakhmanov
Atmospheric and Oceanic Physics
Cold Extremes during Dansgaard-Oeschger Oscillations
Ignacio del Amo and Peter Ditlevsen
This paper studies the statistics of extreme cold air surface temperatures in a
climate that experiences abrupt changes. We employ a CCSM4 simulation of Last Glacial Maximum conditions that exhibits rapid switching between stadial and interstadial states as data. Non-stationary linear Generalized Extreme Value (GEV) distributions are fitted to find the regions that show the most prominent changes and associate them with physical processes. The results are then compared with a non-linear model, which gives a more detailed picture of how the parameters change as a function of the AMOC strength. While different regions of the world show different extremal behaviours, many regions show an approximately linear relationship between the parameters of the GEV distributions and the strength of the AMOC within the stadial and interstadial states, with some non-linear oscillation or jump where the transition between them takes place. Physical processes such as the expansion and retreat of the sea ice and the relative changes in the strength of the currents are shown to impact the magnitude and variability of the extremes, with significant changes observed in the three parameters of the GEV. They also create teleconnections that are compared whenever possible with various proxies for the temperature of the air and the water. We show how mapping the parameters of the GEV distributions into the AMOC strength gives a way to compare results between different
climate models and different
climate states. Comparisons, however, need to pay heed to the dynamical characteristics of the state and the location to be meaningful.
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Atmospheric and Oceanic Physics
Radiative and Dynamical Controls on the Land-Ocean Warming Contrast in Climate Models
Paolo Giani, Arlene M. Fiore, Raffaele Ferrari et al. (+3 more)
Surface air over land warms substantially more than over the ocean under greenhouse forcing, a phenomenon known as the land-ocean warming contrast. Current explanations for this contrast are commonly expressed either in terms of energetic constraints, from top-of-atmosphere and surface energy balance, or dynamical constraints, from large-scale atmospheric dynamics. We show that these perspectives are complementary when viewed through the lens of atmospheric moist static energy (MSE) transport, and that connecting them yields new insight into the controls of the warming contrast and the spread in
climate models. We use this framework to construct an interpretable emulator that reproduces the land-ocean warming response across 22 models from the latest Coupled Model Intercomparison Project (CMIP6). We find that the strength of the land-ocean warming contrast emerges from the interplay between a model-dependent radiative baseline and a robust dynamical restoring mechanism that favors greater warming over land. This interplay leads to two broad model regimes that align with
climate sensitivity. In low-
climate-sensitivity models, more stabilizing radiative feedbacks over the ocean directly favor greater land warming. In high-
climate-sensitivity models, radiative feedbacks alone would instead favor greater ocean warming, but a strong MSE-transport feedback (approximately 0.2 PW/K) more than compensates for this tendency. The intermodel spread in the land-ocean warming contrast is closely related to the ratio of radiative feedbacks over land and ocean, highlighting a broader connection between
climate sensitivity and the land-ocean warming contrast.
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All authors Paolo Giani, Arlene M. Fiore, Raffaele Ferrari, Paul A. O'Gorman, Vincent T. Cooper, Noelle E. Selin
Quantum Gases
Finite-temperature mass gap and quench dynamics of mobile impurities in a Fermi gas
Baihua Gong
Recently, a mass-gap description of mobile
impurities in a
Fermi gas was introduced, which connects Anderson's orthogonality catastrophe for static
impurities to the quasiparticle picture of
Fermi polarons through a
recoil-induced energy gap in the fermionic dispersion. That description, however, was restricted to zero temperature and did not address dynamics. Here we generalize the mass-gap model to finite temperature by combining the Lee–Low–Pines transformation with a self-consistent Hartree–Fock decoupling of the
recoil-induced interaction, and we study the quench dynamics within this framework using the functional-determinant approach. At finite temperature the effective mass gap obeys the self-consistency equation $\Delta(T)=2U_F\tanh[\Delta(T)/4k_B T]$, with $U_F=k_F^2/2M$ and $M$ the
impurity mass. This equation admits a nonzero solution below the characteristic temperature $T^*=U_F/(2k_B)$ and closes as $(T^*-T)^{1/2}$. We identify this closing as the mean-field signature of the thermal melting of the polaron and molecule quasiparticles. Computing the Ramsey response $S(t)$ after a sudden quench of the
impurity–
fermion interaction, we find that its long-time oscillations—
quantum beats between the bound and in-gap states—disappear precisely above $T^*$. Our work ties the thermodynamic and dynamical fingerprints of polaron formation to a single temperature-dependent mean-field parameter.
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Mesoscale and Nanoscale Physics
Jessica Richter, Max J. Ruckriegel, Jonas D. Gerber et al. (+12 more)
Bilayer graphene (BLG)
quantum dots (QDs) are a promising platform for
semiconductor qubits. However, the low-frequency charge noise that may ultimately limit coherence has remained largely unexplored. Here, we systematically characterize charge noise in gate-defined BLG QDs using transport-based noise spectroscopy. We extract a median amplitude of $ S_\mu^{1/2} (1~\text{Hz}) = 1.16~\mu\text{eV}/\sqrt{\text{Hz}}$, placing BLG well within the range reported for established
semiconductor quantum-dot platforms. Across variations in charge occupation, confinement, source-drain bias, and charge-sensor operating conditions, neither the noise amplitude nor the spectral dependence shows a reproducible trend in electrostatic tuning, indicating that we extracted the intrinsic
semiconductor noise. Consistent noise levels are further observed in double QDs and confirmed using an independent superconducting resonator-based dispersive readout. Extending the study to BLG devices incorporating transition metal dichalcogenide layers reveals no measurable charge noise increase in weakly proximitized QDs. These results validate BLG as a viable platform for coherent
quantum information processing.
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All authors Jessica Richter, Max J. Ruckriegel, Jonas D. Gerber, Tijl Degroote, Christoph Adam, Markus Niese, Lara Ostertag, Clara Galante, Kenji Watanabe, Takashi Taniguchi, Petar Tomic, Artem O. Denisov, Hadrien Duprez, Klaus Ensslin, Thomas Ihn
Cosmology and Nongalactic Astrophysics
Prospects for probing dark matter with filamentary 21cm emission
Yizhou Liu, Yingjie Jing, Haoran Shi et al. (+1 more)
The
cosmic web contains most of the matter in the Universe, and its filamentary structure is closely related to the properties of dark matter. Compared with the cold dark matter (CDM) model, warm dark matter (WDM) suppresses the formation of low-mass
halos and produces smoother
cosmic filaments. In this work, we explore whether filamentary 21cm emission can be used to distinguish between these two dark matter models at $z=4$ and $2.5$. We generate intrinsic 21cm brightness temperature maps from cosmological hydrodynamical simulations and produce mock observations by convolving them with Gaussian beams of different angular resolutions. We then compare the predicted filament signals with the expected sensitivities of SKA1-Low and SKA2-Low. We find that the intrinsic 21cm emission clearly reflects the different filament morphologies in the CDM and WDM models, particularly at $z=4$. However, these differences rapidly disappear as the beam size increases, especially for beam sizes larger than 6 arcsec. Although larger beams improve the observational sensitivity, they also erase the small-scale structures that encode the dark matter information. As a result, neither SKA1-Low nor the planned SKA2-Low can directly resolve individual filaments with sufficient sensitivity to distinguish between the two models. We therefore conclude that direct imaging of
cosmic filaments and constraining dark matter through their morphology are unlikely to be feasible with current and planned SKA-Low facilities.
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All authors Yizhou Liu, Yingjie Jing, Haoran Shi, Huijie Hu
High Energy Physics (Phenomenology)
Light Leptoquarks in a Dark Sector: Scalar Dark Matter, Neutrino Mass, and Collider Signatures
Priyotosh Bandyopadhyay, Kirtiman Ghosh, Anirban Karan et al. (+2 more)
We investigate the dark matter (DM) phenomenology and subsequent
collider signatures of a dark leptoquark (LQ) model containing dark vector-like
quarks (VLQs) and a scalar singlet. The dark LQs and VLQs participate in the radiative generation of Majorana
neutrino masses at one loop. Since the coloured LQs and VLQs cannot serve as viable DM candidates, a $\mathbb{Z}_2$-odd singlet scalar is introduced as the DM candidate. The $\mathbb{Z}_2$-odd nature of the LQs forbids their conventional decays into a
quark and a
lepton, allowing them to evade the standard LHC constraints that apply to visible LQ signatures. This framework therefore offers the distinctive possibility of sub-TeV dark LQs coexisting with TeV-scale dark VLQs. These sub-TeV dark LQs help in achieving the observed relic abundance of the singlet through co-annihilation. We analyse the resulting DM phenomenology and assess the prospects for probing this scenario at a future
muon collider.
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All authors Priyotosh Bandyopadhyay, Kirtiman Ghosh, Anirban Karan, Snehashis Parashar, Debabrata Sahoo
High Energy Physics (Phenomenology)
A Bayesian Pixel Based Approach for Model Independent TMD Reconstruction
Marco Zaccheddu
We introduce a nonparametric pixel-based framework for the
Bayesian inference and imaging of transverse momentum dependent (TMD) parton distributions. The methodology integrates TMD
evolution within the Collins-Soper-Sterman formalism in a differentiable framework, and leverages generative AI through a hybrid normalizing flow-driven Metropolis-Hastings
algorithm for efficient posterior sampling. The framework is validated through multi-scale closure tests of increasing complexity. Using singular value decomposition, we characterize the existence of null TMDs, functional components that remain unconstrained by observables, and demonstrate how multi-scale data break these degeneracies, enabling 3D partonic imaging.
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Medical Physics
HPC Modeling of Coupled Elastic-Acoustic Wave Propagation in Biological Media: Numerical Validation
Fawad Ali, Carlos García and Lapo Boschi
Accurate numerical models of sound propagation through biological media are an important tool for many applications, from medical physics to studying the auditory system of humans or other animals. We model high-frequency elastic and acoustic wave propagation through the head anatomy of a common bottlenose dolphin (Tursiops truncatus), by means of the open-source software packages specfem3d, based on the spectral-element method, and \textsc{k-wave}, based on the pseudospectral method. To achieve sufficiently high performance, we ported the latter solver to C++, for Multi-GPU CUDA support via the slab-decomposition of three-dimensional Fast
Fourier Transform approach. Because the two schemes differ fundamentally in how the propagation medium is discretized and internal (in particular fluid-solid) interfaces are treated, similarity between modeled signals across methods is a legitimate measure of model accuracy. Plane waves, depending on time like four-cycle sinusoidal bursts of varying central frequency (20–100 kHz), are numerically propagated through a computed-
tomography-based anatomy model using both solvers. The sound is “recorded” in front of the rostrum and at the right inner-ear locations for comparison. We successfully cross-validate both solvers on high-fidelity High-Performance Computing (HPC) clusters. We find that the stability of results from both solvers grows as the corresponding spatial resolution is refined. At their highest resolutions, the two methods show excellent agreement, with normalized correlation exceeding 0.99 across the entire 20–100 kHz frequency range. Together, our results provide a validated HPC-simulation framework for wave propagation in biological media, with broader implications, e.g., for biosonar research, auditory biomechanics, and medical ultrasound.
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Optics
Machine learning-assisted design and explainable optimization of CdSnP2-based integrated solar-photodetector devices
Md. Alamin Hossain Pappu, Kazi Abrar Shafin, Mainul Hossain et al. (+1 more)
CdSnP2-based integrated
solar cell-photodetector (SC-PD) devices employing CdS and CuGaSe2 (CGS) as the window and back surface field (BSF) layers, respectively are investigated using a hybrid machine learning (ML)-assisted SCAPS-1D framework. Device optimization is performed by varying the thickness, doping concentration, and defect density of individual layers. SCAPS-generated data are used to train six ML models and one deep learning model, with ensemble-based
algorithms exhibiting the highest predictive accuracy. The ML-guided optimization identifies the n-CdS/p-CdSnP2 (CTP)/p+-CGS architecture as the optimum configuration among thirteen candidate structures. Incorporation of a 200 nm CGS BSF layer significantly enhances both photovoltaic and photodetection performance, increasing the efficiency from 20.67% to 32.69%, responsivity from 0.53 AW-1 to 0.72 AW-1, and detectivity from 2.51x1014 Jones to 1.78x1016 Jones. SHapley Additive exPlanations (SHAP) analysis reveales that band-offset engineering, particularly at the window/absorber and absorber/BSF interfaces, together with absorber properties, governs device performance. These findings demonstrate the potential of CdSnP2 and the proposed data-driven SCAPS-ML framework for the accelerated design of high-efficiency multifunctional optoelectronic devices.
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All authors Md. Alamin Hossain Pappu, Kazi Abrar Shafin, Mainul Hossain, Jaker Hossain
Quantum Physics
Ignacio B. Acedo, Javier Gonzalez-Conde, Pablo Rodriguez-Grasa et al. (+2 more)
We introduce Coherent
Quantum Learning (CQL), a training framework for
quantum learning models in which the model parameters are
quantum degrees of freedom evolved under a
Hamiltonian that encodes the loss function. Current
quantum machine learning retains classical optimization: parameters are updated by a classical outer loop using gradient estimates from measurements, and
quantum coherence has no role in the training dynamics, just as in any classical treatment of the same problem. In the
quantum case, a parameter register initialized in superposition evolves unitarily, and probability amplitude concentrates near low-loss configurations through interference, without gradient computation or classical feedback. We give an explicit construction using block encodings and
Hamiltonian simulation, applicable to arbitrary parameterized
circuits. Numerical experiments on binary classification and interferometric phase estimation confirm that the evolved distribution peaks at the optimal parameters, matching gradient-based performance. The construction is compatible in principle with fault-tolerant implementations and extends to batched training via sequential
Hamiltonian evolution.
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All authors Ignacio B. Acedo, Javier Gonzalez-Conde, Pablo Rodriguez-Grasa, Barry C. Sanders, Lirandë Pira
Quantum Physics
Entanglement dynamics of accelerated atoms with environment-induced interactions
Xuerui Zhou, Chenhao Ma and Zixu Zhao
We investigate the influence of environment-induced interactions on the
entanglement dynamics of two uniformly accelerated atoms coupled to a fluctuating massless scalar field with a reflecting boundary. The two atoms are aligned vertically to the boundary. The
entanglement behaviors are influenced by the competition between the environment-induced interatomic and the environment-induced atom-plate interactions, which can be characterized by certain critical values. The maximum of concurrence generated during
evolution decreases non-monotonically with the acceleration, which implies the anti-Unruh phenomenon can exist for some situations even when both environment-induced interatomic and the environment-induced atom-plate interactions are considered.
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Nuclear Experiment
Measurement of the forward angle $^{12}$C+$^{12}$C fragmentation differential cross sections at 62 MeV/nucleon
G. Guo, G. Casini, B. H. Sun et al. (+31 more)
The present work reports on high-precision measurements of forward-angle fragmentation differential cross sections for the [12]C +[12] C reaction at 62 MeV/nucleon using the FAZIA array. Angular distributions for fragments from Z = 1 to 6 were extracted in the range 2 <= theta_lab <= 8 degrees. Particle identification was achieved by combining the Delta E - E technique with Pulse Shape Analysis, and precise energy calibrations were performed. The results show that for heavier fragments, the angular distributions are better described by the Van Bibber formulation than by the Goldhaber model, consistent with the dominance of a wide component from dissipative processes in the measured angular range. Notably, alpha particles exhibit an anomalously narrow angular distribution, likely originating from the intrinsic cluster structure of [12]C. Comparisons with existing data at the same incident energy show very good agreement, with a more complete set of species reported here, while a kinematic scaling is proposed to compare our data with previous experimental data at 50 and 95 MeV/nucleon.
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All authors G. Guo, G. Casini, B. H. Sun, S. Barlini, A. Camaiani, C. Frosin, I. Lombardo, O. Lopez, S. Piantelli, I. Tanihata, S. Terashima, S. Valdré, G. Verde, F. W. Zhao, L. Baldesi, B. Borderie, R. Bougault, C. Ciampi, I. Dekhissi, J. A. Dueñas, Q. Fable, F. Gramegna, D. Gruyer, A. Hocine, B. Hong, S. Kim, T. Kozik, S. H. Nam, N. Le Neindre, J. Park, M. Parlog, E. Vient, M. Vigilante, C. J. Wang
Physics and Society
Dynamic probabilistic decision networks
V.I. Yukalov and E.P. Yukalova
A new type of decision networks is suggested and its operation is analyzed. The network nodes are represented by intelligent
agents who can denote either some biological beings, like humans, or
neurons of the
brain, or the nodes of artificial intelligence. The specifics of the network are in the following: It is probabilistic in the sense that the choice, accomplished by each
agent, is characterized by the related probability. It is dynamic, with the probabilities varying in time due to the exchange of information between the
agents. It is affective, because the
agents choose between alternatives by taking account of utility as well as of biases and
emotions. In general, it is heterogeneous, being composed of the groups of
agents with different properties, for instance having long-term
memory and short-term
memory. The network dynamics, caused by the information exchange, results in decision error decrease. The network operation is illustrated by the example starting with the Allais paradox, its resolution, and the decision error diminution in the process of decision dynamics with information exchange. Resorting to machine-learning techniques it is possible to regulate the behavior of the network
agents forcing them to choose particular alternatives.
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Quantum Physics · Cross-listed from cs.CC
Random Garbage Creates Exponential Quantum Query Separations
Khaled Elbassioni, Rishikesh Gajjala and Saurabh Ray
We prove an exponential separation between standard (XOR)
quantum queries and forward-erasing queries for a Boolean property of injective functions, answering a question of Aaronson~\cite{Aaronson2021Open}. We also obtain an exponential separation for a Boolean promise problem on permutations, where forward in-place queries are
unitary but inverse queries are not supplied. Our construction follows Aaronson's suggestion of appending fixed random garbage to a Simon function. Let $X=\{0,1\}^n$ and $N=2^n$. We use the injection $f_{h,r}(x)=(h(x),x,r_x)$, where $h:X\to X$ is promised to be either a permutation or a Simon function, and $r:X\to X$ is an arbitrary tag table that is reused on every query. The resulting problem is solvable with at most $n+2$ standard queries, but requires $\Theta(\sqrt N)$ forward-erasing queries, matching classical collision sampling.
Embedding these instances into permutations, with the copy of $x$ replaced by a single bit that keeps the
embedding injective, gives a promise problem on permutations of $L=4N^2$ elements that requires $O(\log L)$ standard queries versus $\Theta(L^{1/4})$ forward in-place queries. The lower bounds use the recording method. We replace each query by a nearby contraction that records
cells of a purified tag table. After $T$ queries, tracing out the purified tag table yields a sum of positive-semidefinite contributions, each depending on $h$ at no more than $T$ addresses. A query-by-query hybrid bounds the trace-norm difference between the actual and auxiliary final operators by $O(T/\sqrt N)$. Random permutations and random Simon functions have the same restriction distribution on such a set unless it contains a hidden Simon pair, an event of probability $O(T^2/N)$. Consequently, the actual final states in the two cases remain close unless $T=\Omega(\sqrt N)$, giving the required lower bounds.
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Soft Condensed Matter
Pseudospectral Methods and Critical Phenomena
Jake Skelton, Joseph Brader, Salomée Tschopp et al. (+1 more)
We employ pseudospectral methods to solve the homogeneous Ornstein-Zernike (OZ) equation for a model fluid in the vicinity of the critical point. Focusing on the Mean-Spherical Approximation (MSA) as a closure to the OZ equation, we obtain numerical estimates for the critical exponents $\eta$, $\delta$ and $\gamma$ for a system of hard-core Yukawa particles both in two and three dimensions. The three-dimensional MSA exponents are already well-known from an analytic solution and are recovered by our numerical methods. The two-dimensional exponents are a new output of this work. The pseudospectral method allows for rapid and highly accurate solution of
liquid-state integral equation theories, and enables calculations on truely infinite domains, as needed for highly correlated states. In addition, we analyse the standard Picard iteration scheme and propose a variation of it which provides increased stability and speed of convergence.
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All authors Jake Skelton, Joseph Brader, Salomée Tschopp, Benjamin Goddard
Quantum Physics
Quantum Quasi-Monte Carlo: a window for pre-asymptotic quantum advantage
Paolo Recchia, Zhan Yu, Kelvin Koor et al. (+1 more)
Numerical integration with Monte Carlo methods is a central computational task in many scientific and industrial applications, including financial derivative pricing and risk management. Classical Monte Carlo
algorithms are computationally demanding: achieving an accuracy $\epsilon$ typically requires a number of function evaluations scaling as $O(1/\epsilon^2)$.
Quantum-accelerated Monte Carlo methods based on
quantum amplitude estimation can in principle quadratically improve this dependence. However, quasi-Monte Carlo methods have not been explored in the
quantum context. In this work, we introduce a
quantum quasi-Monte Carlo
algorithm that combines low-discrepancy nets with
quantum amplitude estimation. The proposed method prepares the quasi-random point set coherently in superposition. The method does not yield an asymptotic improvement over classical quasi-Monte Carlo, since the total error separates into a discretization error, determined by the finite net, and a
quantum estimation error. Instead, we explore a pre-asymptotic advantage window: for a target accuracy that would classically require $2^q$ low discrepancy points, one can prepare a higher-resolution net of size $2^Q$, with $Q>q$, in superposition and reach the same accuracy using significantly fewer function queries. This window can be controlled by tuning the
circuit resolution and amplitude-estimation parameters, making the approach relevant for practical regimes where the number of queries is finite rather than asymptotically large.
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All authors Paolo Recchia, Zhan Yu, Kelvin Koor, Patrick Rebentrost
High Energy Astrophysical Phenomena
NuSTAR View of the 2025 Mini-Outburst of the Black Hole X-ray Binary GRS 1739-278: Spectral and Timing Evolution in the Soft State
Arshad Hussain and Umananda Dev Goswami
We present a dedicated timing and spectral analysis of three NuSTAR observations of the
Galactic black hole candidate GRS 1739-278 obtained during the decay of its 2025 mini-outburst (September 18-30, 2025). The source is found in a soft, disk-dominated state throughout, with a declining $3$-$79$ keV count rate (from $112.4$ to $99.4$ cts s$^{-1}$), a low and only mildly evolving hardness ratio ($\approx0.14$-$0.16$) and a fractional variability that drops from $3.2\%$ to $1.1\%$; no periodic or quasi-periodic signal is detected in the power spectrum or the Lomb-Scargle periodogram of any observation. Joint FPMA+FPMB spectral fits with an absorbed disk-blackbody plus thermal-Comptonization continuum, together with a broad, high-significance ($11.7$-$15.0\sigma$)
curvature feature near $10$-$12$ keV (an empirical proxy for a strong disk-reflection/returning-radiation component) describe the $4$-$30$ keV spectra well ($\chi^2/{\rm dof}=1.04$-$1.15$). The inner-disk temperature cools steadily from $1.021\pm0.001$ to $1.002^{+0.003}_{-0.002}$ keV while the disk normalization and hence the derived inner radius, $R_{\rm in}\simeq27.7$ km $\simeq0.95\,R_{ISCO}$ remains constant to within $0.3\%$, consistent with a disk anchored at the innermost stable circular orbit throughout. The unabsorbed $4$-$30$ keV luminosity declines from $1.35\times10^{37}$ to $1.15\times10^{37}$ erg s$^{-1}$ ($0.67\%$ to $0.57 L_{Edd}$). These results of the spectral-timing characterization of the 2025 mini-outburst are broadly consistent with a high-
spin black hole accreting at a low, steadily declining rate in the canonical soft state.
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Disordered Systems and Neural Networks
Spectral properties of deterministic matrices multiplied by rotationally invariant random non-Hermitian ensembles
Pierre Bousseyroux and Marc Potters
In this paper, we study spectral properties of multiplicative deformations of non-Hermitian random
matrices. We consider
matrices of the form $\mathbf{A}\mathbf{B}$, where $\mathbf{A}$ is a deterministic $N\times N$
matrix (not necessarily Hermitian) and $\mathbf{B}$ is a rotationally invariant random
matrix. We show that, as $N\to\infty$, the boundary of the complex
eigenvalue distribution of $\mathbf{A}\mathbf{B}$ is governed by simple equations involving the $\mathcal{R}_1$ and $\mathcal{R}_2$ transforms of $\mathbf{B}$.
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High Energy Astrophysical Phenomena
KM3NeT/ARCA stacking search for high-energy neutrino point sources: the case of ultra-luminous infrared galaxies and blazars
The KM3NeT Collaboration
A stacking search for high-energy astrophysical
neutrino emission is presented using three candidate source populations: ultra-luminous infrared
galaxies and two categories of blazars, specifically high-synchrotron-peaked BL Lacs and extreme blazars. The analysis is based on 336 days of data from the Astroparticle Research with Cosmics in the Abyss component of the KM3NeT research infrastructure (KM3NeT/ARCA), collected with detector configurations comprising 19-21 detection units, yielding 1544 selected track-like
neutrino candidates. The sample of ultra-luminous infrared
galaxies consists of 75 sources, for which conventional power-law spectra are assumed in modelling their signal emission. The blazar samples comprise 232 high-synchrotron-peaked BL Lac objects and 88 extreme synchrotron-peaked emitters, respectively. Their expected
neutrino fluxes are obtained from numerical tools constrained by multi-wavelength observational data. No statistically significant excess above the atmospheric background is found for the three catalogues and 90% confidence level upper limits are set.
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Astrophysics of Galaxies
C3PO: A Ly{\alpha} Emitting Galaxy at $z \sim 9$
Weida Hu, Casey Papovich, Taylor A. Hutchison et al. (+6 more)
We present deep, $>10$ hr, JWST NIRSpec G140M and G395M observations of a previously known
galaxy C3PO-8447 at $z=8.99781$. Our new NIRSpec data from the Carbon-3 plus Oxygen (C3PO) survey detect Ly$\alpha$ emission with an escape fraction of $1.5\pm0.3\%$ and a velocity offset of $210\pm80$ km s$^{-1}$, making C3PO-8447 the third Ly$\alpha$ emitting
galaxy confirmed at $z\gtrsim 9$. The
galaxy has a low
stellar mass of $2.2\pm0.1\times 10^7\ M_\odot$, a young
stellar age of $1.6\pm0.2$ Myr, and a low oxygen abundance of $12+\log(\mathrm{O/H}) = 7.50\pm0.08$. UV diagnostic diagrams incorporating the C IV, O III], and C III] emission lines indicate that the ionization of C3PO-8447 is dominated by the recent starburst. The low Ly$\alpha$ escape fraction of C3PO-8447 implies that C3PO-8447 resides in a small ionized bubble with radius $R \sim 0.07$ to 0.20 pMpc, which can be produced by C3PO-8447 alone. We find no evidence for either a large-scale
galaxy overdensity around C3PO-8447 or a significant contribution from nearby
galaxies to its ionizing
photon budget. Taken together, these results suggest that C3PO-8447 likely represents an ionized bubble powered by a single low-mass, vigorously
star-forming
galaxy during the early stages of
cosmic reionization.
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All authors Weida Hu, Casey Papovich, Taylor A. Hutchison, Rebecca L. Larson, Pablo Arrabal Haro, Steven L. Finkelstein, Nikko J. Cleri, Lu Shen, Jiayang Yang
Statistical Mechanics
Frenkel line of Yukawa fluids within the self-consistent relaxation theory
Ilnaz I. Fairushin and Anatolii V. Mokshin
For a simple model fluid, the Yukawa fluid, the condition for dynamic crossover, known as the Frenkel line, is defined. The condition is related to the fact that the roton minimum in the dispersion relation of longitudinal acoustic-like excitations exists only when the collective vibrational dynamics of particles dominates in the
liquid. Based on the self-consistent relaxation theory for the Yukawa fluid, thermodynamic states are determined in which the roton minimum disappears. The obtained values of the state parameters for the Frenkel line are consistent with the results of studies in which the position of this line on the phase diagram of the Yukawa fluid was determined using molecular dynamics simulations. It is shown that the Frenkel line in this system can be determined directly from the structural characteristic – the static structure factor. A physical interpretation of the roton minimum frequency for the simple
liquids near the Frenkel line is proposed.
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Soft Condensed Matter
Patterned Substrates Unlock Self-Electrophoretic Phenomenon in Active Janus Microswimmers
Jyoti Sharma, Yashpal Singh Brar, Omar Tricinci et al. (+3 more)
Inert colloids half-coated with platinum (Pt) are a standard model of chemically powered active particles, yet the microscopic origins of their propulsion in hydrogen peroxide (H2O2) remain difficult to dissect experimentally. Whereas self-diffusiophoresis was the prevailing theory, self-electrophoresis has been more recently suggested as the main mechanism of propulsion. According to the latter mechanism, the pole-to-equator Pt-thickness gradient produced by directional metal deposition is sufficient to create anodic and cathodic regions on the metal cap and thereby generate an electric field sustained by H2O2 decomposition. Enhancing self-propulsion performance of such particles thus requires precise control over the Pt thickness distribution, which is currently not achievable with standard methods (e.g. evaporation or sputtering). Here, we propose a method to fabricate Janus active particles by assembling silica microspheres on patterned substrates containing spherical grooves whose depth and spacing set the degree of particle coating while simultaneously suppressing proximity-led defects (Pt bridges). The resulting particles exhibit a tunable platinum-thickness contrast, as verified by Focused-Ion-Beam cross-sections. In 2.5% H2O2, our results suggest that this control can significantly increase propulsion efficiency, while providing evidence indirectly supporting the hypothesis that self-electrophoresis is the dominant mechanism. These results demonstrate that our patterned-substrate route can enhance control over the catalyst deposition and enable novel Janus morphologies, allowing for more precise engineering of active colloids.
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All authors Jyoti Sharma, Yashpal Singh Brar, Omar Tricinci, Paola Parlanti, Mauro Gemmi, Stefano Palagi
Data Analysis and Statistics · Cross-listed from cs.LG
Neural-Network Maxent: a general extension with learned nonlinearity, applied to time-series for Desert Locust distribution modelling
Alessandro Grassi, Edoardo Kimani Bellotto, Wassim El Azami et al. (+2 more)
Species Distribution Modelling (SDM) is essential for understanding how environmental conditions shape biodiversity, particularly for destructive pests such as the Desert Locust (Schistocerca gregaria), whose breeding dynamics are tightly coupled to rapidly evolving environmental conditions. Maxent has become the dominant method for presence-only data, but its reliance on a linear combination of hand chosen feature transforms limits its ability to capture the nonlinear, temporal relationships common in ecological monitoring, where
covariates such as precipitation, soil moisture, and vegetation indices evolve meaningfully over time. Standard implementations flatten time-series
covariates into independent features, discarding sequential structure that carries critical signal. We introduce RNN Maxent, an extension of the Maxent framework that replaces the fixed feature dictionary with a neural network, specifically a Gated Recurrent Unit (GRU), trained end to end via backpropagation. The approach preserves Maxent's presence only statistical foundations, background normalization, and probability calibration, differing only in that the nonlinearity is learned from data rather than fixed in advance. We apply RNN Maxent to map suitable habitat for the Desert Locust using 50 day environmental time series derived from ERA5 Land, MODIS, and Sentinel 3, maintaining a 7 day gap between
covariates and presence records to yield
forecasting behavior. Compared against standard Maxent, RNN Maxent improves performance across metrics (ROC AUC 0.862 std 0.036 vs. 0.792; F1 0.671 std 0.056 vs. 0.590).
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All authors Alessandro Grassi, Edoardo Kimani Bellotto, Wassim El Azami, Sabrina Outmani, Maximilien Houel
Data Analysis and Statistics
Reduced latent leakage does not reliably predict lower likelihood bias in collider inference
Tong Pan
Reusable
collider representations can be evaluated through downstream discrimination and probes of retained information, but neither quantity directly tests the behaviour of score templates in a profiled likelihood. We test a specific prediction in a controlled two-channel routing protocol: if reduced physics-label readability in a nuisance branch indicates a more inference-robust representation, it should accompany a smaller profiled signal-strength bias under fixed unmodelled shifts. In a public Compact
Muon Solenoid $H\rightarrow ZZ\rightarrow4\ell$ workflow, a downstream split of fixed EveNet
embeddings preserves signal/background area under the receiver operating characteristic curve ($0.9894\pm0.0004$) while reducing nuisance-branch physics readability from $0.961\pm0.013$ to $0.593\pm0.030$. Probe-sensitivity and effective-rank controls exclude a failed readout and branch collapse. In a separate top
quark jet-tagging workflow, the leakage reduction recurs with preserved task performance. Across two development event shards, however, its Spearman association with maximum absolute profiled bias is $0.036$, and three of six material leakage-improving transitions do not reduce that bias. A one-shot preregistered confirmation on an independently accessed shard produces material leakage reductions in all three paired seeds, while the maximum absolute bias increases in two. Thus, within the tested protocol, latent readability is a useful routing diagnostic but not a likelihood-robustness certificate. The result supports a practical validation rule: claims about inference robustness require a prespecified likelihood-facing stress test and held-out confirmation.
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