Earth and Planetary Astrophysics
Modeling the Impact of Starspot Inhomogeneity on Spectroscopic Retrievals of Directly-Imaged Planets
Alex R. Howe, Natasha Latouf, Christopher C. Stark et al. (+2 more)
Stellar activity is a major complication in the detection and characterization of
exoplanets by both radial velocities and transits, and the upcoming Habitable Worlds Observatory (HWO) invites us to also consider its effect on direct imaging. Spectra of directly-imaged
planets can vary with the activity of their host
stars because the face of the
star we see is not the same as the face reflected by the
planet. This discrepancy could potentially result in inaccurate measurements of the
planet's radius and unexpected, externally-caused variability in its contrast spectrum with the
star. To assess the scientific capabilities and requirements of HWO, it is important that the magnitude of these effects be quantified. We present results of model
retrievals of Earth-like
exoplanets observed with an HWO-style survey, as they would appear when affected by starspots, using the ExoVista code for spectrum generation and the BARBIE code for spectroscopic
retrieval. Both
Solar-type
stellar activity and highly active rapid rotators are considered and compared with an idealized quiescent host
star. In the quiescent case, ${\rm SNR}\approx5$ is needed to detect atmospheric water vapor at 0.9 microns and ${\rm SNR}\approx13$ at 0.74 microns. We find that for
Solar-type activity, the effect on
retrievals will be negligible, but it could present problems for certain highly-active
stars at limiting geometries. For an extreme case with a single large spot with 10% coverage not visible to the observer, the SNR required for water detection increases to ${\rm SNR}\approx8$ at 0.9 microns and ${\rm SNR}\approx18$ at 0.74 microns. It also decreases the accuracy of the retrieved albedo, resulting in a value $\sim2/3$ of the true value. In light of these results, we estimate the impact that
stellar variability and starspots may have on an HWO-style survey.
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All authors Alex R. Howe, Natasha Latouf, Christopher C. Stark, Avi M. Mandel, Veselin Kostov
Quantum Physics
Deploying and validating a metropolitan QKD secure network: architecture and field performance
Claudia De Lazzari, Nicola Biagi, Damiano Giani et al. (+15 more)
The advent of cryptographically relevant
quantum computers poses an existential threat to classical public-key infrastructure.
Quantum Key Distribution (QKD) addresses this challenge by providing information-theoretic security for key establishment, independently of any computational hardness assumption. In this work, the deployment and experimental validation of a metropolitan-scale
quantum-secure network between data centers in Milan is reported. The network operates over installed fiber infrastructure and implements a layered architecture integrating QKD hardware, standards-compliant Key Management (KM), and centralized Software-Defined Networking (SDN) orchestration. Dynamic path reconfiguration via active optical switching and trusted-node routing allow automated fail-over solutions. Application-layer validation across diverse protocols and workloads confirms the seamless interoperability of all system components. These results establish the technical and operational readiness of metropolitan QKD networks for production deployment, and offer a replicable blueprint for building
quantum-secure communication infrastructure at metropolitan scale.
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All authors Claudia De Lazzari, Nicola Biagi, Damiano Giani, Marco Russo, Fernando Chirici, Francesco Stocco, Saverio Francesconi, Giacomo Ferranti, Alessandro Soureal, Antonella Sanguineti, Bartolomeo Montrucchio, Christian Laurenzi, Oliviero Testa, Guglielmo Morgari, Antonio Manzalini, Tommaso Occhipinti, Alessandro Zavatta, Davide Bacco
Chemical Physics
Robust nuclear hyperpolarization of small molecules through intermolecular transfer of parahydrogen-derived polarization
Bogdan A. Rodin, Anna Parker, Laurynas Dagys et al. (+12 more)
The recent advent of hyperpolarization techniques, which can enhance NMR signals by several orders of magnitude relative to thermally polarized samples, has enabled applications traditionally out of reach due to the inherently low sensitivity of NMR techniques. However, a high barrier to entry remains, as most hyperpolarization approaches either require complex instrumentation or are applicable only to a relatively small set of molecules. Here we introduce PHIPNOE, a platform that directly addresses both limitations. PHIPNOE is based on parahydrogen-induced polarization (PHIP), which is well-established as a scalable route to hyperpolarization requiring minimal instrumentation, but has been mostly restricted to molecules that undergo specific chemical reactions. We overcome this barrier by tailoring PHIP to create highly polarized, highly concentrated solutions of one specific molecule, which acts as an intermediate source of polarization. This 'source molecule' then distributes polarization to a broad range of target molecules mixed into the solution, via the
spin polarization-induced
nuclear Overhauser effect (SPINOE). We investigate chemical influences on PHIPNOE, and develop a predictive model to estimate enhancement based on molecular mass and T1 relaxation times. A complete run from PHIP hyperpolarization to PHIPNOE polarization transfer and signal detection takes less than one minute, the approach does not require any modifications to the NMR spectrometer, and enhancements are repeatable across molecular classes. PHIPNOE thus enables applications including single-shot multidimensional NMR, real-time monitoring of dynamic processes, and, with 300-fold signal amplification demonstrated on a benchtop spectrometer, practical low-field NMR, where we show enhanced sensitivity in detecting per- and polyfluoroalkyl substances (PFAS).
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All authors Bogdan A. Rodin, Anna Parker, Laurynas Dagys, Vitaly Kozinenko, Martin Korzeczek, Martin B. Plenio, Salvatore Mamone, Rokas Šakalys, Federico De Biasi, Ran Wei, Pinelopi Moutzouri, Lyndon Emsley, Stephan Knecht, James Eills, Ilai Schwartz
Mesoscale and Nanoscale Physics
High-field Josephson effect enabled by a moiré Hofstadter spectrum
A. Díez-Carlón, M. Cárdenes Wuttig, N. Wei et al. (+7 more)
Magnetic fields generally suppress phase-coherent Josephson transport, limiting superconducting interferometry to relatively low fields. Here we show that moiré-engineered
graphene Josephson junctions can overcome this constraint. Using ballistic
graphene/hBN junctions, we establish phase-coherent Andreev transport through Fabry-Pérot oscillations and Fraunhofer interference that persist across both the primary Dirac cone and reconstructed moiré minibands. We then demonstrate phase-coherent Josephson interference up to 6 T in the fractal Hofstadter-butterfly regime, well beyond the range expected for conventional ballistic
graphene junctions. Comparison with Hofstadter-spectrum calculations reveals that superconductivity survives where the moiré potential transforms Landau levels with quenched group velocity into dispersive
magnetic Bloch bands with finite quasiparticle group velocity, enabling extended electron-hole Andreev trajectories across the junction. Our results show that Hofstadter minibands can stabilize phase-coherent superconductivity deep into the parameter domain conventionally associated with the
quantum Hall regime, establishing a new platform for high-field superconducting interferometry.
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All authors A. Díez-Carlón, M. Cárdenes Wuttig, N. Wei, D. Ivanov, P. Altpeter, P. Hakonen, K. Watanabe, T. Taniguchi, L. I. Glazman, D. K. Efetov
Quantum Physics
Interlocked Time Crystal in Coupled Spin-1/2 Ensembles under Local Dissipation
Zhen-Huan Yang, Zhen-Tao Liang and Dan-Bo Zhang
Multilevel dissipative systems can exploit multiple local transitions and coherence channels to generate nonstationary time-crystalline dynamics. Here we show that an analogous mechanism can be synthesized without enlarging the local
Hilbert space by coupling two locally pumped and decaying
spin-1/2 ensembles into a composite dissipative unit.Neither ensemble supports an autonomous oscillatory phase; instead, opposite pump-decay imbalances and inter-ensemble exchange coupling can lead to a single interlocked time
crystal with a fixed internal phase relation and no single-ensemble counterpart. The time-crystalline character is consistently established through the mean-field analysis, exact calulation of Liouvillian spectra at finite size, and temporal correlations with cumulant expansion. Our work establishes a route to dissipative time-crystalline order in which coupling between simple two-level subsystems generates the effective internal structure otherwise provided by multilevel constituents.
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Astrophysics of Galaxies
Saurabh Mittal, Thomas Siegert, Francesca Calore et al. (+12 more)
The origin of the 511 keV line signal in the Milky Way remains unresolved despite decades of observations. The measured flux of $\sim 3 \times 10^{-3}\,\mathrm{ph\,cm^{-2}\,s^{-1}}$ suggests a steady-state positron injection rate of $\sim 10^{43}$-$10^{44}\,\mathrm{e^+\,s^{-1}}$. One proposed contributor to this signal is
stellar flaring activity since high energy
Solar flares are known to produce positrons and associated annihilation radiation. We estimate the quasi-persistent 511 keV luminosity expected from flaring
stellar populations and estimate the
Galactic contribution. We constrain the 511 keV fluxes for different sources in the
Galaxy, and in particular globular clusters. Using
Solar flare observations as a calibration baseline, we construct a hierarchical
Bayesian model to link
flare energy to 511 keV luminosity. We further use
flare frequency-energy distributions to estimate the time-averaged positron output of
stellar populations. The resulting predictions are compared with INTEGRAL/SPI observations using spatial and population-based models. We find that
stellar flares fall short by several orders of magnitude in explaining the
Galactic positron annihilation rate. Reproducing $\sim10\%$ of the observed luminosity in the
Galactic bulge would require unphysically large maximum
flare energies per
star reaching up to $E_\mathrm{{max}} \gtrsim 10^{37-39}\,\mathrm{erg}$. Spatial modeling further shows that
stellar flare scenarios cannot reproduce the observed 511 keV morphology.
Stellar flares cannot be the dominant source of
Galactic positrons. Although previous studies have shown that the measured 511 keV morphology is broadly consistent with old
stellar populations, our results exclude normal
stellar flaring activity as the underlying source for this emission.
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All authors Saurabh Mittal, Thomas Siegert, Francesca Calore, Fiona H. Panther, Pasquale D. Serpico, Hiroki Yoneda, Niklas C. Bauer, Tristan Bouchet, Laura Eisenberger, Mika A. Gelowicz, Tomohiko Oka, Rudi Reinhardt, Manuel R. H. W. Skalka, Dimitris Tsatsis, Manja L. Zimmerer
Quantum Physics
Quantum Arithmetic Circuits in Public-Key Cryptography
Siyi Wang, Kyungbae Jang, Hyunji Kim et al. (+4 more)
Quantum computing has advanced rapidly in recent decades, driven by developments across the technology stack, including
quantum error-correcting codes and efficient
quantum algorithms. Among these,
quantum arithmetic
circuits serve as fundamental building blocks for various promising
algorithms. Despite their crucial role, the design of
quantum arithmetic
circuits faces challenges arising from the no-cloning
theorem,
qubit limitations, and
circuit depth constraints, which significantly impact the efficiency of large-scale
quantum computing. We provide an overview of
quantum arithmetic
circuits in the context of public-key cryptanalysis, with particular emphasis on optimization strategies such as measurement-based uncomputation and conditionally clean ancilla. We review state-of-the-art designs for essential arithmetic operations in public-key cryptanalysis such as addition, multiplication, and modular exponentiation. We also present an overview of the techniques used for fault-tolerant runtime and resource estimation in
quantum cryptanalysis. In brief, this chapter emphasizes strategies for designing resource-efficient
quantum arithmetic
circuits, providing a basis for realistic evaluations of
quantum cryptanalytic capabilities.
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All authors Siyi Wang, Kyungbae Jang, Hyunji Kim, Anik Basu Bhaumik, Anubhab Baksi, Hwajeong Seo, Anupam Chattopadhyay
Materials Science · Cross-listed from cs.LG
CatRetriever: Contrastive Representation Learning for Slab-to-Bulk Retrieval in Generative Catalyst Discovery
Jungho Oh, Woosung Kim, Dong Hyeon Mok et al. (+2 more)
Inverse design is an emerging data-driven paradigm for efficiently navigating vast chemical spaces to discover new materials with targeted properties, and in the context of heterogeneous catalysis, surface generative models have recently advanced this goal by directly generating catalyst surface-adsorbate structures. However, these models typically operate at the slab level and do not provide the corresponding parent bulk structure, making it difficult to assess bulk-dependent properties such as formation energy, surface energy, crystallographic
symmetry, and synthesizability. Here, we address this missing slab-to-bulk connection as a
retrieval problem and introduce CatRetriever, a contrastive representation learning model that aligns slab and bulk
crystal representations in a shared latent space. From a slab query, CatRetriever accurately retrieves plausible parent bulk candidates with R@1 > 91% and R@3 > 98% on both the in-distribution and holdout evaluation sets. We further extend the CatRetriever framework into an adsorption energy targeted bulk discovery pipeline that combines bulk
retrieval, generative search space expansion, and adsorption energy distribution analysis. This workflow evaluates candidates by both structural compatibility with the query slab and their ability to access the target adsorption energy range across diverse surface environments. CatRetriever therefore provides a scalable route for connecting catalyst generative models with physically plausible and adsorption energy compatible bulk catalyst discovery.
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All authors Jungho Oh, Woosung Kim, Dong Hyeon Mok, Jonggeol Na, Seoin Back
Chemical Physics
Correlation-consistent Gaussian basis sets for copper solids from material-constrained atomic optimization
Jincheng Yu, Xiaoyu Zhang, Min-Ye Zhang et al. (+3 more)
Correlation-consistent Gaussian basis sets are central to systematic molecular
quantum chemistry, but their direct use in periodic solids is often limited by severe linear dependence from diffuse atomically optimized primitives. This problem is particularly acute for metallic and metal-containing systems, where reliable complete-basis-set (CBS) extrapolation is needed for correlated-wavefunction
benchmarks. We introduce material-constrained atomic optimization (MCAO), a basis-set optimization framework that preserves the atomic and correlation-consistent character of Gaussian basis sets while penalizing large overlap-
matrix condition numbers in representative solids. As a proof of concept, we generate Dunning-style MCAO-cc-pVXZ basis sets (X = D, T, Q) for Cu with all-electron, scalar-relativistic all-electron, effective core potential (ECP), and pseudopotential treatments. The resulting basis sets remain numerically stable for Cu solids and surfaces while reproducing molecular Cu dimer energetics and plane-wave reference properties of bulk Cu. CBS-extrapolated random-phase approximation calculations further enable a controlled assessment of pseudopotential, relativistic, and basis-set errors in bulk Cu and CO adsorption on Cu(111), providing scalar-relativistic all-electron Gaussian-basis
benchmarks for the CO adsorption puzzle.
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All authors Jincheng Yu, Xiaoyu Zhang, Min-Ye Zhang, Yu Cao, Qiming Sun, Hong-Zhou Ye
Quantum Physics
Near-Optimal Mode Scaling for Finite-Dimensional Boson Sampling via Lie-Algebraic Leakage Bounds
Chon-Fai Kam and En-Jui Kuo
Boson sampling demonstrates
quantum advantage through the interference of indistinguishable particles, with output probabilities governed by
matrix permanents. Realizing it on deterministic, matter-based platforms requires encoding the bosonic modes in finite-dimensional local
Hilbert spaces, which introduces a leakage channel absent in linear optics: multi-particle bunching beyond the local truncation $d$. We develop a unified framework for non-interacting sampling on the irreducible representations of compact Lie groups, in which the transition amplitude is the immanant of a submatrix of the single-particle transition
matrix, recovering the permanent in the bosonic case. Within this framework we bound the bunching leakage through a Dyson-series analysis: decomposing the correlated many-body leakage operator into independent random
matrices and applying non-commutative concentration inequalities, we prove, in a Gaussian model of the transition
matrix, that its spectral norm concentrates at $\tilde{O}(\sqrt{n})$ rather than the $O(n)$ worst-case of prior
spin-based emulations; the passage to the physical Haar ensemble is reduced to a single submatrix-comparison input, verified at leading order. Exact numerics across local dimensions $d=2$–$5$ indicate that the bound is tight, the Haar-ensemble norm matching the closed form $\sqrt{d(n-d+1)}$ to sub-percent accuracy. This tightens the required mode number from $m=\Omega(n^4)$ to the near-optimal $m=\tilde{\Omega}(n^{1+2/(d-1)})$; for a
spin-1 representation ($d=3$) the overhead falls to $m=\tilde{\Omega}(n^2)$, matching the collision-free threshold. The result is independent of particle statistics and applies across finite-dimensional Lie-symmetric architectures, quantifying the spatial resources needed to preserve sampling hardness.
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Mesoscale and Nanoscale Physics
Thermodynamic bound on the Fano factor of a coherent thermoelectric heat engine
Nahual Sobrino, Rosario Fazio and Matteo Acciai
We show that for fermionic coherent thermoelectric transport, selecting heat-engine operation yields a thermodynamic uncertainty relation for the charge current that imposes a universal lower limit of $F > 1/2$ on the corresponding Fano factor. We find that violations of the thermodynamic uncertainty relation for classical Markov processes, typically associated with a
quantum advantage, are far more restricted for heat engines than what is allowed by a generic thermodynamic process. For bosonic and classical carriers, the minimum Fano factor increases to $F > 1$, and the thermodynamic uncertainty relation for classical Markov processes is never violated. We provide numerical evidence that all the obtained bounds are tight and can be saturated by properly designed transmissions.
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Quantum Physics
$\mathtt{Q^2SAR}$: overcoming classical bottlenecks in drug discovery via quantum multiple kernel learning
Mariano Caruso, Daniel Ruiz, Alejandro Giraldo et al. (+1 more)
Quantitative Structure-Activity Relationship ($\mathtt{QSAR}$) modeling is a foundational computational methodology in early-stage drug discovery, heavily relied upon for predicting compound toxicity, bioavailability, and therapeutic potential. However, classical methods often struggle to effectively map the highly complex, non-linear, and high-dimensional interactions inherent in molecular data, leading to reduced predictive accuracy and costly late-stage clinical failures. In this paper, we present a
Quantum Multiple Kernel Learning ($\mathtt{QMKL}$) framework, dubbed Next-Gen $\mathtt{Q^2SAR}$, that leverages
Quantum Support Vector Machines ($\mathtt{QSVMs}$) to overcome these classical limitations. By encoding molecular descriptors into exponentially large
quantum Hilbert spaces, our approach substantially enhances the expressiveness of non-linear modeling. Benchmarking our
quantum-enhanced framework on a
dataset targeting the $\mathtt{DYRK1A}$ kinase (a critical target for Alzheimer's disease), the $\mathtt{QMKL}$-$\mathtt{SVM}$ achieves an impressive Area Under the Curve ($\mathtt{AUC}$) score of $0.8750$, significantly outperforming classical state-of-the-art Gradient Boosting models ($\mathtt{AUC} = 0.8037$). Furthermore, we establish a theoretical and empirical pathway toward resolving classical data bottlenecks through projected
quantum kernels ($\mathtt{PQK}$) and measurement accelerators. As
quantum computing architecture matures, this framework paves the way for autonomous cognitive architectures and self-improving drug discovery pipelines, promising to unlock deeper insights across vast chemical spaces and to accelerate the development of life-saving therapeutics.
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All authors Mariano Caruso, Daniel Ruiz, Alejandro Giraldo, Guido Bellomo
Astrophysics of Galaxies
JWST NIRCam and MIRI Reveal the Dust-Producing AGB Population of NGC 6822
Conor Nally, Olivia C. Jones, Laura Lenkić et al. (+9 more)
We present a photometric catalogue of the Local Group
dwarf galaxy NGC 6822 based on deep JWST observations obtained with the Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). Point-spread-function photometry and band matching were performed with StarbugII. The resulting catalogue contains 864,114 NIRCam point sources and 17,235 MIRI detections, with 10,079 detected in both instruments. Blackbody fitting yields effective temperatures and bolometric luminosities for 119,621
stars, providing a detailed view of the resolved
stellar content. Candidate evolved
stars were selected from NIRCam-MIRI colour-magnitude diagrams, with the sample refined by removing resolved contaminants and excluding young
stellar objects through spectral energy distribution (SED) fitting. The final sample of 1226 evolved
stars was analysed using the Grid of Red Supergiant and Asymptotic
Giant Branch Models (GRAMS), from which
dust-production rates were obtained and carbon-rich or oxygen-rich asymptotic
giant branch (AGB) classifications assigned via a likelihood-weighted comparison across the full model set. Across the JWST fields, evolved
stars return 5.6 x 10^-7 Msun yr^-1 of
dust to the interstellar medium, with oxygen-rich AGB
stars contributing 60% and carbon-rich AGB
stars 35%, despite the low
metallicity of NGC 6822. The unexpectedly high oxygen-rich contribution indicates the presence of intermediate-mass AGB
stars undergoing hot-bottom burning, in line with the recent
star-formation history of NGC 6822.
Dust-producing AGB
stars exhibit a centrally concentrated carbon-rich population and a more extended oxygen-rich population. We also identify JWST colour relations that provide robust photometric
estimators of
dust-production rates for evolved
stars.
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All authors Conor Nally, Olivia C. Jones, Laura Lenkić, Annette M. N. Ferguson, Nolan Habel, Alec S. Hirschauer, Margaret Meixner, P. J. Kavanagh, Martha L. Boyer, Omnarayani Nayak, B. Sargent, P. Scicluna
Physics Education
From Prompt Engineering to Epistemic Prompting: Prompt Trajectories as AI-Mediated Problem Framing in Science Education
Matteo Tuveri
Prompt engineering is commonly presented as a technical competence for obtaining more accurate, relevant, or well-formatted outputs from large
language models (LLMs). However, in STEM education, prompting should also be understood as a continuous epistemic practice. Students interpret contextual and disciplinary cues and adopt expectations about what kind of knowledge, representation, and action are appropriate. Drawing on epistemological framing, and AI-mediated concept-to-decision
reasoning, the paper presents a new framework called epistemic prompting and proposes a multi-turn Framing-Prompting Loop. The educationally relevant outcome is a
prompt framing trajectory: the sequence of
prompts, model responses, learner uptake, disciplinary checks, and reframing moves through which a knowledge task develops. In this framework, an initial
prompt establishes a provisional macro-frame by selecting the problem, representations, assumptions, criteria, and distribution of work between learner and model. Each subsequent learner turn can then maintain, specify, challenge, repair, or transform that organization. The implications for AI-mediated STEM instruction, and, specifically, on learner-LLM interaction are also discussed.
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Strongly Correlated Electrons
Electronic tuning of the soft-phonon transport anomaly in Ta$_2$Ni(S$_x$Se$_{1-x}$)$_5$
Yuan-Shan Zhang, Masahiko Isobe, Hidenori Takagi et al. (+1 more)
Ta$_2$NiSe$_5$ continues to be investigated for its phase transition at $T_\textrm{c}$ = 326 K, where it develops both an electronic gap and a distortion of its Ta/Ni chains. One intriguing feature at $T_\textrm{c}$ seen in thermal transport is the
giant anisotropic scattering of
phonons moving perpendicular to the chains, which is apparently associated with the softening of a transverse acoustic
phonon, but whose microscopic origin and significance demand clarification. By tuning the normal-state band overlap/gap with S substitution, we uncover a close connection between this soft-
phonon transport anomaly and underlying electronic instabilities: When Ta$_2$Ni(S$_x$Se$_{1-x}$)$_5$ approaches a band
insulator at high $x$, and signatures of the electronic transition are suppressed, the soft-
phonon transport anomaly concomitantly vanishes. Our results establish the following picture for the Ta$_2$Ni(S$_x$Se$_{1-x}$)$_5$ family: Near the S end, a sole
lattice instability gives rise to a weak structural transition with $T_\textrm{c}$ approaching 130 K. Near the Se end, additional electronic instabilities boost $T_\textrm{c}$ up to 326 K and amplify experimental signatures of the transition. The strong interaction between electrons, holes, and the
lattice is manifested as a soft-
phonon transport anomaly accompanied by electronic fluctuations, which include excitonic and hybridization-gap fluctuations.
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All authors Yuan-Shan Zhang, Masahiko Isobe, Hidenori Takagi, Dennis Huang
Earth and Planetary Astrophysics
Water gas discs in exo-asteroid belts
Paul Huet, Quentin Kral and Louis Manchon
Observations of tens of secondary CO gas discs associated with cold exo-Kuiper belts together with other arguments have led Kral et al (2024) to propose that water ice could also sublimate in exo-asteroid belts, suggesting a new pathway for the delivery of water to terrestrial
planets, including Earth. We aim to model such water vapour discs and to characterise their physical properties across a range of extrasolar systems with different host
stars. We further investigate the implications for the
accretion of this water by potential
planets located in the inner regions of these systems. We adapt and extend the model of Kral et al (2024) to follow the outgassing, photodissociation, and viscous
evolution of water vapour discs. We perform a suite of simulations exploring the parameter space, focusing on the
stellar mass, the mass of the parent belt, and its orbital location. We additionally include an inner
planet to estimate the mass of water accreted as a function of disc properties and system architecture. We find that systems hosting Sun's mass (and higher)
stars produce water vapour very efficiently, sublimating nearly all of the ice initially present in the belt. In most cases, the bulk of the gas mass is generated early, when the
stellar luminosity is highest. The amount of water accreted by inner
planets can approach the initial ice mass of the belt, leading to
planets with water inventories comparable to or exceeding those of Earth, potentially creating ocean
planets. We find that water outgassing occurs early after the protoplanetary disc dissipates in systems containing exo-asteroid belts. ALMA, JWST and ELT are capable of detecting this water vapour for several tens of millions of years, even in relatively low-mass water discs. Hence, if such water gas discs are present, they should be detectable with current facilities.
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Astrophysics of Galaxies
Up, Up, and Away? Quantifying ISM Fallback using Ram Pressure Stripping Simulations
Harrison J. Souchereau, Stephanie Tonnesen, Jingyao Zhu et al. (+1 more)
The
evolution of the cold interstellar medium (ISM) in satellite
galaxies orbiting through massive hosts is an important factor in how they evolve while experiencing ram pressure stripping (RPS), as cold molecular gas clouds are the most difficult ISM component to fully strip and serve as the sites of
star formation. We investigate ISM
evolution using a suite of hydrodynamical wind tunnel simulations with an intermediate mass ($M_* = 10^{9.7}$ M$_\odot$)
galaxy orbiting in a Coma cluster-like environment, varying the disk-wind angle. Even if the ultimate fate of a ram pressure stripped
galaxy is complete gas removal, we find that cold gas evolves through cycles of
outflow and inflow (fallback). We show that fallback can be identified at a wide range of wind angles, but is elevated for angles closer to edge-on and occurs predominantly in a specific quadrant (trailing side, rotating into the wind). Most inflow occurs in gas that never leaves an “inner tail" region that extends to $\sim20$ kpc. We discuss possible reasons for when and why fallback occurs using simple idealized simulations. For a highly inclined disk, offset rotational motion is a major driver of fallback, while disk shadowing and cloud growth can act at all wind angles. Lastly, we discuss the relative importance of each mechanism at different stages of a
galaxy's
evolution under ram pressure, and compare our findings with instances of ISM fallback detected in observed RPS
galaxies.
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All authors Harrison J. Souchereau, Stephanie Tonnesen, Jingyao Zhu, Jeffrey D. P. Kenney
Solar and Stellar Astrophysics
Unstable magnetospheric accretion on the T Tauri star TW Hya
J.-F. Donati, P.I. Cristofari, C. Moutou et al. (+9 more)
In this paper we present new spectropolarimetric and velocimetric observations of the prototypical classical T Tauri
star TW Hya obtained with SPIRou at the Canada-France-Hawaii
Telescope, expanding our previous monitoring over two new seasons (2024 and 2025). We confirm that the large-scale
magnetic field of TW Hya varied with time, and find that it showed fluctuations on a timescale of about a year in addition to the longer term variations outlined in the previous study. Using Zeeman-Doppler imaging, we obtain that the large-scale field of TW Hya mostly consisted of a poloidal dipole of mean polar strength 0.83 kG, inclined at an average 17degr to the rotation axis. We also find that the radial velocities of TW Hya, once fully filtered from telluric contamination, were dominated by rotational modulation induced by activity, with residuals of 32 m/s rms. No signal from a putative close-in
planet is found, with an upper limit on the
planet mass ranging from 0.33 to 0.98 Mjup for distances of 0.053 to 0.41 au from the central
star. Emission lines indicate that the mass
accretion rate was equal to $10^{-8.33\pm0.20}$ Msun/yr on average, with peak-to-peak fluctuations by a factor of ~5 from season to season. This confirms that
accretion onto TW Hya is unstable, with the magnetospheric gap carved by the large-scale field at the center of the disk extending on average no further than 33-40% of the corotation radius where the disk Keplerian angular velocity equals the rotation rate at the
stellar surface.
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All authors J.-F. Donati, P.I. Cristofari, C. Moutou, A. Carmona, A. Lavail, J. Bouvier, K. Perraut, S.H.P. Alencar, M. Audard, K. Grankin, F. Ménard, M. Takami
Fluid Dynamics · Cross-listed from cs.LG
A multi-scale feature enhanced graph neural network for fluid dynamics prediction in complex geometries
Li Xiao, Tianyu Li, Yiye Zou et al. (+2 more)
Industrial design in fields such as vehicle and aerospace engineering often relies on large-scale numerical simulations to evaluate fluid dynamics performance, which can incur substantial computational costs. Deep neural networks have shown promise in improving simulation efficiency, especially graph neural networks (GNNs), which demonstrate great potential due to their flexibility with unstructured data. However, GNNs face challenges when dealing with tasks involving complex geometries and large-scale meshes. In this paper, we propose the Multi-scale Feature Enhanced Graph Neural Network (ME-GNN) to tackle these challenges. ME-GNN employs a graph neural network with a two-step message-passing mechanism to capture detailed local features effectively. Additionally, it integrates an
Attention U-Net with uniform grid discretization, enabling the extraction of both fine and coarse features. The model also utilizes K-hop sampling to construct subgraphs, facilitating efficient training on large
datasets while preserving detailed local features. We evaluated ME-GNN on three
benchmark datasets and achieved state-of-the-art results: a relative L2 error of 0.0196 for the velocity field and 0.0556 for the surface pressure on ShapeNet-Car, a normalized mean squared error of 0.0033 for the flow field on AirfRANS, and a relative L2 error of 0.1416 for the surface pressure on DrivAerNet.
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All authors Li Xiao, Tianyu Li, Yiye Zou, Mingjie Zhang, Xiaogangd Deng
Optics
Analytical Theory of Photon Tunneling and Near-Field Heat Transfer Between Dissimilar Materials
Kartika N. Nimje, Mariano Pascale and Georgia T. Papadakis
Near-field radiative heat transfer can exceed the blackbody limit through evanescent-mode coupling across nanoscale gaps. This enhancement underpins applications including thermophotovoltaic energy conversion, electroluminescent cooling, thermal rectification, and
photon absorption in plasmon-assisted photodetection. These systems most often involve
photon- or heat-exchange between dissimilar interfaces, particularly between a
semiconductor and a metal. Despite the prevalence of this asymmetric configuration, no closed-form description of its near-field interaction exists. Here, we derive a closed-form analytical description of
photon tunneling that clarifies the roles of material properties, namely the
plasma frequency, optical loss, and
semiconductor absorption, in the thermal exchange. We show that the dominant in-plane wave vector of the radiative heat transfer is an approximate average of the corresponding values for two symmetric reference systems: a plasmonic-plasmonic cavity and a
semiconductor-
semiconductor cavity. These results establish a compact analytical framework for near-field heat transfer between dissimilar materials.
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High Energy Astrophysical Phenomena
Extending the infrastructure of the BAM code towards resistive general-relativistic magnetohydrodynamics: tests and first applications
Matthew Beaudoin, Maximilano Ujevic, Ramon Jaeger et al. (+4 more)
Many astrophysical phenomena, including
pulsars and short gamma-ray bursts, are associated with the extremely strong
magnetic fields present in
neutron stars and
neutron star mergers. While the ideal magnetohydrodynamic approximation, which assumes infinite conductivity, provides an excellent description of the
neutron-
star interior, it cannot capture non-ideal processes such as Ohmic dissipation and
magnetic reconnection. To overcome this limitation, we present an extension of the numerical-relativity code BAM incorporating a resistive general-relativistic magnetohydrodynamic (GRMHD) description. We validate the new implementation through an extensive suite of special-relativistic magnetohydrodynamic
benchmark tests and by performing stable simulations of isolated and binary
neutron star systems. For the latter, we investigate the impact of finite conductivity on
magnetic-field amplification, mass ejection, and non-ideal GRMHD effects. In particular, we find that the component of the electric field parallel to the
magnetic field, which is zero in the ideal case, can reach up to 10% of the total electric field strength. This highlights the potential importance of non-ideal effects for accurately modeling the long-term
evolution of post-merger remnants, particularly in low-density regions. Although the present study is restricted to simplified piecewise-polytropic equations of state, it demonstrates the capabilities of the new resistive GRMHD framework and paves the way for future investigations employing more realistic microphysics.
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All authors Matthew Beaudoin, Maximilano Ujevic, Ramon Jaeger, Anna Neuweiler, Henrique Gieg, Kenta Kiuchi, Tim Dietrich
Statistical Mechanics
Still life in a classic Blume-Capel model: pseudo-transitions in a spin-1 diamond chain
Elham Shahhosseini Shahrabadi, Majid Moradi and Jozef Strecka
We exactly investigate the ground-state,
magnetic, and thermodynamic properties of a
spin-1 Blume-Capel diamond chain in a
magnetic field by means of the transfer-
matrix method. After establishing the complete ground-state phase diagram and characterizing each ground-state
spin configuration, we examine the finite-temperature behavior in the vicinity of selected phase boundaries and triple points. It is demonstrated that an extremely small energy gap between a nondegenerate ground state and competing macroscopically degenerate low-lying excited states gives rise to entropically-driven pseudo-transitions. These pseudo-transitions manifest themselves through abrupt but continuous changes in the magnetization and
entropy resembling discontinuous jumps, while the
magnetic susceptibility and specific heat exhibit exceptionally sharp yet finite peaks resembling divergences. Our results provide the exact evidence that pseudo-transitions can also emerge in the classical
spin-1 Blume-Capel model and thereby extend the class of one-dimensional
spin systems known to display pseudo-transitions.
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Quantum Physics
Multi-Stage Mamba-Based Architecture for Fast and Scalable Superconducting Qubit Readout
Luca Otting, Xiaorang Guo, Emmanouil Giortamis et al. (+3 more)
Reliable
qubit readout is a critical bottleneck toward fault-tolerant
quantum computing (FTQC). In superconducting
quantum processors, readout operations are both error-prone and high-latency. These challenges become more severe in frequency-multiplexed architectures, where signal crosstalk among neighboring
qubits significantly degrades readout fidelity. Existing machine learning (ML)-based approaches rely on feed-forward neural networks (FNNs) that suffer from large parameter sizes and lack an end-to-end network that jointly addresses relaxation errors and discriminates
qubit states. In this work, we present a multi-stage
qubit state discriminator based on the Mamba model, which enables efficient sequence modeling with linear complexity. The first stage performs initial state discrimination, followed by a refinement stage that identifies and mitigates relaxation-induced errors. Our lightweight model achieves a
geometric mean readout fidelity of 0.906, outperforming the best-reported state-of-the-art method while reducing parameter size by 49.6%; our optimal model further reaches 0.911. Both models remain robust across varying input trace lengths, maintaining a high fidelity of 0.893 at readout durations as short as 500 $ns$, achieving up to a 26% reduction in logical error rate over prior work in
quantum error correction (QEC).
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All authors Luca Otting, Xiaorang Guo, Emmanouil Giortamis, Benjamin Lienhard, Pramod Bhatotia, Martin Schulz
Quantum Physics · Cross-listed from cs.PL
The Time-Space Complexity of Checking Multiple Assertions in Quantum Programs
Shengyuan Yang and Charles Yuan
Runtime assertions are a promising mechanism for testing and debugging
quantum programs. But unlike the classical world, checking a
quantum program that contains multiple assertions often requires using additional space or running the program additional times. For example, on current
quantum hardware where mid-
circuit measurement is restricted or costly, an assertion's pass/fail outcome cannot be revealed immediately. Instead, it is routed into an ancilla
qubit during execution and read out by a terminal measurement. For a program with $n$ assertions, a naive strategy uses $n$ ancillas to learn all $n$ outcomes, while an alternative uses one ancilla but repeats program execution over $n$ rounds, checking one assertion per round. Both satisfy $S \cdot T = O(n)$, where $S$ is the number of ancillas and $T$ the number of executions: a fundamental time-space trade-off. Can one do asymptotically better? We reveal that the answer depends sharply on the information to be learned. Reporting the outcomes of all assertions requires linear complexity, but two partial-information tasks of detecting whether any assertion fails, and of identifying the first failing assertion, require only logarithmic complexity – an asymptotic improvement. Moreover, the checking strategies for these tasks can trade time for space in useful ways. In this work, we formalize the complexity of checking multiple assertions in a
quantum program. Using this definition, we establish its landscape of asymptotic lower bounds and constructive upper bounds. We confirm via a case study on Grover's
algorithm that the resource costs of constructed strategies match theoretical predictions, illustrating the practical design space for
quantum programmers.
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Instrumentation and Detectors
Effects of irradiation by protons, neutrons, and gamma particles on electrical properties of 4H-SiC diodes and LGAD sensors
Jiří Kroll, Pavla Federičová, Jan Chochol et al. (+15 more)
4H-SiC is a wide-bandgap
semiconductor with high displacement threshold energy, large critical electric field, and low intrinsic carrier concentration, making it attractive for radiation-hard detector applications. In this work, we investigate the electrical characteristics of 4H-SiC P$^{+}$-in-N (PN) diodes and Low-Gain Avalanche Detectors (LGADs) fabricated by onsemi before and after irradiation by 24 GeV/c
protons, reactor
neutrons, and $^{60}$Co gamma rays. Current-voltage (IV) and capacitance-voltage (CV) measurements were performed at room temperature for
proton fluences up to $1\times10^{16}\;\mathrm{protons/cm^2}$,
neutron fluences up to $1\times10^{18}\;\mathrm{1\;MeV\;n_{eq}/cm^2}$, and total ionizing doses up to 300 kGy.
Hadron irradiation induces pronounced changes in both leakage current and bulk capacitance, consistent with radiation-induced formation of deep acceptor-like defects and strong compensation of the originally N-type material. For high
proton fluences, the leakage current decreases and the bulk capacitance becomes bias-independent, indicating effective compensation of the epitaxial layer. Extreme
neutron fluences lead to a substantial expansion of the depleted region into the originally highly doped substrate, as inferred from the measured capacitance values. Gamma irradiation up to 300 kGy results in significantly modified capacitance behavior, suggesting reduction of the effective doping concentration in the epitaxial and multiplication layers. The results demonstrate that radiation-induced compensation strongly modifies the effective space charge in 4H-SiC devices at high
hadron fluences, while the leakage current is influenced by the enlarged depletion volume together with field-enhanced and surface-related generation mechanisms. In contrast, ionizing damage primarily affects the effective doping and electric-field distribution.
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All authors Jiří Kroll, Pavla Federičová, Jan Chochol, Adam Klimsza, Jana Kozáková, Adam Kozelský, Vojtěch Kráčmar, Jiří Kvasnička, Roman Malousek, Mária Marčišovská, Michal Marčišovský, Marcela Mikeštíková, David Novák, Radek Novotný, Peter Slovák, Radim Špetík, Peter Švihra, Pavel Tůma
Disordered Systems and Neural Networks
Emergent quantum chaos from correlations on a random graph
Mrinal Sarkar, Valerio Pagni, Tilman Enss et al. (+1 more)
This work demonstrates that sparse long-range random bonds on a one-dimensional
lattice alone can generate
quantum-chaotic spectral correlations and also drive a localization transition in a noninteracting single-particle
Hamiltonian. The model is a one-dimensional ring in which each pair of sites is connected independently with a probability $p_{ij}= d_{ij}^{-(1+\sigma)}$. Each bond carries identical unit hopping and on-site disorder is absent. Despite the absence of on-site disorder and interaction, the model displays
quantum chaotic spectra with Gaussian orthogonal ensemble (GOE) level statistics at small $\sigma$ and localized eigenstates with Poisson statistics at larger $\sigma$. The transition occurs in the range $ 0.80 \lesssim \sigma_c \lesssim 0.85$, far above the summability threshold of the mean hopping profile ($\sigma=0$). A Gaussian field theory retaining only the mean and variance of the Bernoulli bonds instead predicts a threshold at $\sigma=1$, suggesting that higher cumulants are infrared-relevant. Our findings hint towards a universality class that is distinct from both the power-law random banded
matrix model and the standard Anderson transition.
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All authors Mrinal Sarkar, Valerio Pagni, Tilman Enss, Nicolò Defenu
Statistical Mechanics
Thermal phase transitions in a mixed-spin Ising model on the Lieb lattice: Exact results beyond zero magnetic field
Jozef Strecka and Katarina Karlova
We investigate the ground-state and finite-temperature properties of a mixed
spin-1/2 and
spin-1 Ising model on a decorated square (Lieb)
lattice incorporating a uniaxial single-ion anisotropy and
magnetic field. By employing the generalized decoration-iteration transformation, the model is mapped exactly onto an effective
spin-1/2 Ising model on the square
lattice characterized by an effective nearest-neighbor interaction and an effective field. The studied model consequently becomes exactly solvable even for finite values of the applied
magnetic field whenever the effective field vanishes. The ground-state analysis reveals three distinct phases: ferrimagnetic phase (FRI), disordered phase (DP), and
ferromagnetic (FM) phase. The ground-state boundary between FRI and DP phases gives rise to a dome-shaped surface of discontinuous thermal phase transitions, which is terminated by a line of Ising-type critical points associated with continuous thermal phase transitions. Both continuous and discontinuous thermal phase transitions belong to the exactly solvable parameter regime defined by a vanishing effective field in spite of the fact that the applied
magnetic field is finite. Two consecutive discontinuous thermally-induced reentrant phase transitions DP-FRI-DP are identified in a narrow parameter region. The exact analytical predictions including reentrance, field- and thermally-driven phase transitions are independently verified by classical Monte Carlo simulations.
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Solar and Stellar Astrophysics
Mapping Oscillatory Flows in a Giant Chromospheric Spiral
Yash.B.Saneshwar, Eamon Scullion and Gert J. J. Botha
The
solar chromosphere is permeated by complex
magnetic fields that guide
plasma flows and energy into the corona. This work presents a detailed analysis of a unique, high-resolution observation of a
giant chromospheric spiral structure that emerges due to a large
magnetic pore, captured by the Swedish 1-m
Solar Telescope (SST). A comprehensive data analysis pipeline is developed to automatically detect the edges of 2255
plasma flows (loops) that constitute the spiral, and these are used to extract the kinematics of flows propagating along the
magnetic field. The analysis reveals three primary insights into the spiral's physics. First,
magnetic curvature is correlated with oscillatory flow dynamics, i.e. regions of high loop
curvature exhibit a statistically significant excess of higher-order oscillation modes compared to straighter loops; it is also correlated with higher intensity and longer periods. Second, spatial distribution of oscillation period shows an inverse trend, decreasing from $\sim$3.5 minutes in the pore to $\sim$3 minutes in the outer spiral arms. This is interpreted as a signature of the overlying trans-equatorial quadrupolar coronal loop system compressing the pore's field lines into a near-horizontal orientation, producing a period gradient that challenges the standard expanding canopy model. Finally, the emission signature confirms that oscillating threads represent localised channels of brightness that lie within cooler, absorbing loop material. This study provides the first statistical analysis of oscillatory flows in a large-scale spiral, probing energy flow through the chromosphere through curved
magnetic structure.
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Astrophysics of Galaxies
New optical velocities for local galaxy candidates
Maksim Chazov, Igor Karachentsev and Serafim Kaisin
We used the 6-meter BTA
telescope to determine radial velocities for 46
galaxies, previously considered to be nearby objects. Twelve of them have kinematic distances within 13Mpc and are new probable companions to the bright Local Volume
galaxies: NGC1068, NGC2903, NGC4517, NGC4565, NGC4826. We also found a new tiny satellite of the nearby (10.38Mpc) SMC-like
dwarf galaxy DDO46. Two isolated dIrr
galaxies: dw1408-0802 and Dw1552-1027 are probably located inside the Local Void. The spectrum of the latter shows a rich set of emission lines. Using the radial velocities and projected separations of 13 NGC1068 satellites, we estimated the total mass of the group to be $M= (2.6\pm1.0)\times10^{12}\, M_\odot$.
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High Energy Physics (Phenomenology)
Multi-scale improved predictions for $\boldsymbol{pp \to t\bar{t}W^+ +X}$
Nikolaos Dimitrakopoulos and Malgorzata Worek
We compare standard fixed-order NLO QCD predictions for the full off-shell $pp \to e^+\nu_e\, \mu^-\bar{\nu}_\mu\, \tau^+\nu_\tau\, b\bar{b} \, (j) + X$ processes in the multi-
lepton decay channel with the results obtained using the MiNLO approach. The MiNLO method, now also implemented in the Helac-NLO framework, provides a dynamic determination of the renormalization and factorization scale settings by identifying the most likely branching histories of the additional jets through an inverse $k_T$-clustering
algorithm. The inclusion of Sudakov form factors accounts for the large logarithms that arise in the presence of widely separated scales. We perform a dedicated comparison of the two approaches at both the integrated and differential (fiducial) cross-section levels for the LHC Run II energy of $\sqrt{s}=13$ TeV. Finally, we present the merging of the full off-shell predictions for $pp \to e^+\nu_e\, \mu^-\bar{\nu}_\mu\, \tau^+\nu_\tau\, b\bar{b} \, + X$, $pp \to e^+\nu_e\, \mu^-\bar{\nu}_\mu\, \tau^+\nu_\tau\, b\bar{b} \, j +X$ and $pp \to e^+\nu_e\, \mu^-\bar{\nu}_\mu\, \tau^+\nu_\tau\, b\bar{b} \, jj$, with the aim of improving the description of the underlying $pp \to e^+\nu_e\, \mu^-\bar{\nu}_\mu\, \tau^+\nu_\tau\, b\bar{b} + X$ process.
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