Quantum Physics
QSTAR: Quantum Selective Transfer with Adaptive Routing
Saim Rehman, Nouhaila Innan and Muhammad Shafique
Quantum transfer learning (QTL) is often evaluated by replacing a classical classifier with a fixed variational
quantum head, but this hides a key question: when is the
quantum branch actually useful? We propose QSTAR:
Quantum Selective Transfer with Adaptive Routing, a selective QTL framework that keeps high-confidence classical predictions and routes only low-confidence samples to a fallback branch. Using a frozen ResNet18 backbone on Fashion-MNIST, we compare manually designed QTL heads, KetGPT-designed
quantum heads, and parameter-matched classical baselines under a common data split and optimization schedule. Standard QTL heads reach at most 57.0% accuracy, while the strongest KetGPT head in the main filtered sweep reaches 78.5% accuracy and 0.785 F1-score. Although the strongest fixed classical head remains higher at 81.6%, selective routing gives the
quantum branch a clearer role. On low-confidence samples, KetGPT #180 improves accuracy over a parameter-matched MLP fallback by 6.82, 4.31, and 3.03 percentage points at thresholds of 0.70, 0.80, and 0.90. At the full-system level, Adaptive KetGPT-QTL reaches 80.9% accuracy and 0.807 F1-score, outperforming the adaptive classical baseline. A separate compact-
circuit ablation identifies KetGPT #160 as a stronger fixed-head candidate, reaching 81.9% accuracy with only 10
quantum parameters and 9 gates. These results suggest that architecture-searched
quantum heads are most useful as targeted fallback branches for uncertain inputs rather than uniform replacements for classical classifiers.
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Quantum Physics
Cautious optimism for deep parameterized quantum circuits
Marie Kempkes, Elies Gil-Fuster, Carlos Bravo-Prieto et al. (+5 more)
A central challenge in
quantum machine learning is understanding the scaling behavior of parameterized
quantum circuits (PQCs). In particular, it remains unclear how their performance on unseen data changes as the number of trainable parameters increases. Prior works have derived formal generalization guarantees for
quantum models, but it is well-known that many such results do not fully characterize generalization behavior in practice. In this work, we show that gradient-based PQCs can exhibit improved performance on unseen data as model size increases, displaying the phenomenon of double descent. This contrasts with the traditional view that larger models lead to degraded generalization. We provide analytical results rigorously underpinning this behavior by leveraging add-one-in perturbation techniques and spectral properties of random
matrices. We support these results with numerical experiments on re-uploading PQCs across several data sets and training set sizes, consistently observing the predicted double descent behavior. While other obstacles on the path toward practical
quantum machine learning remain, our finding that deeper parameterized
quantum circuits do not necessarily exhibit degraded performance provides reasons for cautious optimism.
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All authors Marie Kempkes, Elies Gil-Fuster, Carlos Bravo-Prieto, Aroosa Ijaz, Alissa Wilms, Jens Eisert, Evert van Nieuwenburg, Vedran Dunjko
Computational Physics
Cycle-Consistent and Uncertainty-Aware Neural Surrogates for Tokamak Edge Plasmas
Abdourahmane Diaw, Sebastian De Pascuale, Jae-Sun Park et al. (+3 more)
The boundary and divertor
plasma govern how a tokamak exhausts power and particles, setting heat fluxes, target conditions, and the onset of detachment. Predicting these quantities is essential for operating current and future devices, but edge simulations that resolve them are too slow for parameter scans, optimization, or real-time control. Machine-learning surrogates offer a fast alternative, yet most are forward-only: they cannot recover input parameters from observations or assess the reliability of their predictions. We introduce a cycle-consistent neural surrogate for edge
plasmas, combining a conditional U-Net forward model with an optimization-based inverse method built on the frozen forward network. The forward model maps five control parameters to two-dimensional
plasma-state fields on the SOLPS-ITER mesh; the inverse method enforces consistency between forward and inverse predictions, a self-supervised quality check needing no ground-truth labels at inference. An ensemble of multilayer perceptrons also predicts electron temperature and density profiles at the outboard midplane and divertor targets, with uncertainty estimates that flag where more simulations are needed. The forward model achieves normalized root-mean-square errors below 2.6% and Pearson correlations above 0.95 for all fields. Cycle-consistency regularization raises the average cyclical $R^2$ from 0.59 to 0.99 without degrading forward accuracy and enables recovery of the core fueling rate; all five control parameters are recovered with Pearson $r\ge0.97$. A $k$-d tree warm start yields a database completion rate above 95%, versus roughly 30% outright failures when cold-started. With about $4\times10^6$ parameters, the model produces full 2D predictions in milliseconds, five to six orders of magnitude faster than SOLPS-ITER, enabling real-time control, parameter scans, uncertainty analysis, and digital twins.
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All authors Abdourahmane Diaw, Sebastian De Pascuale, Jae-Sun Park, Ivan Paradela Perez, Jeremy D. Lore, Stefan Dasbach
Chemical Physics
Towards more accurate natural orbital functional approximations: including 4-index cumulant contributions
Valerii Chuiko, Paul W. Ayers and Eduard Matito
Accurate modeling of bond breaking remains a central challenge for reduced density
matrix functional theory (RDMFT). Although some modern functionals can yield reasonably accurate dissociation energies, they often fail to reproduce key properties of the dissociated fragments, such as a vanishing fragment population covariance (also known as the delocalization index) and the correct total
spin angular momentum of each fragment (local
spin). In this work, we revisit the construction of natural orbital functionals by correcting the cumulant contribution produced by the PNOF5 functional. Our method enforces known contributions of the cumulant to local
spin fragments and the delocalization index at the dissociation limit. We obtain the closest cumulant consistent with these physically motivated constraints and subsequently purify the corresponding one- and two-electron reduced density
matrices by imposing the standard $P, Q, \text{and } G$ $N$-representability conditions. The resulting functional yields improved behavior in strongly correlated regimes. Benchmarking on the dissociation of the singlet states of \ce{N2}, \ce{NO+}, \ce{O2}, \ce{S2}, and \ce{CO} shows that in the dissociation regime the energies computed from the updated cumulant exactly reproduce the complete active space self-consistent field (CASSCF) energies. We further analyze the limitations of the approach and identify scenarios in which the current approach performs poorly. This work provides a pathway for systematically improving natural orbital functionals to achieve reliable bond-breaking calculations within RDMFT.
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High Energy Physics (Theory)
Wilson Towers as Local Bulk Fields
Vishal Gayari and Chethan Krishnan
Multi-winding Wilson loops (Wilson spools) in 2+1-dimensional
gravity can reproduce one-loop partition functions of local free fields in the bulk. Bulk free fields have a second-quantized Fock space, and the AdS/CFT correspondence suggests that the associated multi-particle sectors are dual to multi-trace primaries in the CFT. In this note, we use standard symmetric-function methods to show that the Wilson spool in thermal AdS$_3$ can be recast as a sum over $single$-winding Wilson loops – one for each multi-trace primary. In a companion paper to appear, we will view Wilson networks and TQFTs as the natural
language of non-perturbative bulk
quantum gravity. The present note illustrates how this can apply to $local$ bulk fields, and not just defects: a bulk (generalized free) field is to be viewed as a full tower of multi-trace Wilson lines. We further show that the $SL(2)$ descendants of each multi-trace primary, together with the boundary gravitons of the AdS$_3$ background, correctly reproduce the full Virasoro character of each module. In this
language, the role of a light insertion on a heavy primary is played by a topological Verlinde line. This allows us to obtain a "microscopic" description of one-loop determinants on the smooth BTZ handlebody. A spatially wound probe Wilson line on a
torus with a contractible $thermal$ cycle can be traded for a Verlinde line inserted on a dense family of heavy Polyakov loops – with the roles of the two cycles exchanged, so that the $spatial$ cycle is now contractible. The
vacuum row of the modular $S$-kernel acts as the (approximate) density of the heavy primaries. This reinforces the case made in arXiv:2601.18775 that a smooth horizon is a stand-in for an ensemble of
quantum states, each produced by a heavy Wilson line that appears as a singular horizon in the semi-classical limit.
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High Energy Physics (Phenomenology)
Transverse-momentum resummation effects on angular coefficients in Z and W boson hadroproduction
Stefano Camarda, Giancarlo Ferrera, Lorenzo Rossi et al. (+1 more)
We present a comprehensive analysis of the angular coefficients of $Z$ and $W$
boson production at
hadron colliders in different kinematical ranges, using data from the ATLAS, LHCb, and CMS Collaborations at the LHC, as well as CDF data at the Tevatron. We provide theoretical predictions obtained by consistently combining the resummation of logarithmically enhanced QCD corrections at small transverse momenta $q_T$ up to next-to-next-to-leading logarithmic accuracy (NNLL) with fixed-order calculations at next-to-leading order (NLO), valid at large $q_T$. We quantify the impact of transverse-momentum resummation on the angular coefficients. We find that the inclusion of resummation effects leads to a moderate and systematic improvement in the description of the data in the intermediate $q_T$ region, $q_T \sim 20-50$~GeV, for several angular coefficients, while in the remaining cases it does not degrade the agreement of fixed-order QCD predictions with experimental measurements.
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All authors Stefano Camarda, Giancarlo Ferrera, Lorenzo Rossi, Gabriele Francesco Sala
Chemical Physics
Polaritons of inherently interacting molecules
Gábor J. Halász, Csaba Fábri, Lorenz S. Cederbaum et al. (+1 more)
We investigate the absorption spectra of molecular ensembles strongly coupled to a Fabry-Pérot cavity and establish the microscopic origin of collective polaritonic bands. We show that long-range intermolecular interactions generate a large
manifold of hybrid molecular-photonic states, even without disorder, vibrations, or thermal effects. The observed polariton bands are collective envelopes of these microscopic states, making photonic and molecular spectra strongly dependent on molecular arrangement. Our findings identify long-range intermolecular interactions as a key ingredient of molecular cavity QED.
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All authors Gábor J. Halász, Csaba Fábri, Lorenz S. Cederbaum, Ágnes Vibók
Mathematical Physics
Two-phase source and reaction coefficient Stefan type problems
Targyn A. Nauryz
This paper investigates inverse two-phase Stefan-type problems for
parabolic heat equations with unknown time-dependent source and reaction coefficients. Suitable transformations reduce the original free-boundary problems to equivalent equations on fixed spatial domains, and
Fourier spectral expansions are used to derive reconstruction formulas for the unknown coefficients. In the first formulation, the source coefficients are identified from integral, pointwise, and nonlocal additional data, leading to Volterra integral equations. In the second formulation, an exponential transformation is applied to recover the reaction coefficients. A principal advantage of the model with two moving boundaries is that each boundary provides its own Stefan condition which sufficient to determine the two unknown time-dependent coefficients without additional overdetermination conditions. Under appropriate assumptions the existence, uniqueness, boundedness and regularity of weak and strong solutions are established. Illustrative examples confirm the applicability of the reconstruction procedure and show that the coefficients remain stable under the noisy data. The proposed approach provides a rigorous base for identifying time-dependent thermal parameters in two-phase phase-change processes.
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High Energy Physics (Theory)
High-Order Pole-Skipping in Near-Extremal Holography
Xiang Li, Haiming Yuan and Xian-Hui Ge
We develop a systematic analytic method for studying high-order pole-skipping in near-extremal
holographic black holes. In the near-extremal regime, approaching the limit $T\to0$, the near-horizon geometry develops an approximately $\mathrm{AdS}_2 \times \mathbb{R}^{d-1}$ structure; we show that the mode index $q$ labeling pole-skipping points is identified with the IR conformal dimension $\Delta_{\mathrm{IR}} = q$ in the emergent $\mathrm{AdS}_2/\mathrm{CFT}_1$ correspondence, providing a concrete physical interpretation of the subleading pole-skipping tower. The method reorganizes the near-horizon Frobenius expansion according to powers of temperature. This reveals a temperature-graded hierarchical structure that reduces the $n$-th-order pole-skipping condition to a factorized algebraic equation:each pole-skipping momentum depends only on the mode index $q$, not on the order $n$. This $n$-independence produces a high degeneracy as $T\to 0$, where pole-skipping momenta at all orders collapse onto a discrete set of values determined by near-horizon geometry and the scalar field mass; these values can be expressed in terms of thermodynamic quantities such as
entropy density and specific heat. In the limit $n \gg 1$ (with $nT$ remaining small), the leading pole-skipping momenta grow asymptotically as $k_{n,n} \propto n$. We compute leading temperature corrections and verify our predictions through numerical analysis of the Dyonic Gubser–Rocha model. The results confirm that high-order pole-skipping at low temperature is governed by near-horizon physics. This provides analytic access to pole-skipping points well beyond those accessible by standard determinant methods and clarifies the structure of
holographic Green's functions in the low-temperature regime.
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High Energy Astrophysical Phenomena
Ultra-High-Energy Particle Production in Binary Mergers Endowed with Magnetic Fields
Carlos H. Coimbra-Araujo, Rita C. Anjos, Jonas P. Pereira et al. (+1 more)
We study the production of ultra-high-energy particles via the Bañados–Silk–West (BSW) mechanism in the pre-merger phase of binary systems detected by LIGO-Virgo-KAGRA. By solving the geodesic equations for charged particles in magnetized Kerr spacetime with fields of $B \sim 10^{12}$–$10^{14}$~G, we demonstrate that collisions near the horizon can achieve center-of-mass energies $E_{\mathrm{cm}} \sim 10^{18}$– $10^{20}$~eV, placing them firmly in the ultra-high-energy
cosmic-ray (UHECR) range. We systematically explore the parameter space of merger remnants, varying black hole mass ($M \sim 20$–$150\,M_\odot$, characteristic of the binary black hole population), dimensionless
spin ($\chi_f \sim 0.7$–$0.9$),
magnetic field strength, and particle angular momenta. Our analysis reveals three distinct acceleration regimes: a
gravity-dominated regime ($B < 10^{12}$~G) with negligible
magnetic enhancement; a transition regime ($10^{12}~\text{G} \lesssim B \lesssim 10^{13}~\text{G}$) where gravitational and
magnetic effects compete; and a
magnetic-dominated regime ($B > 10^{13}$~G) where fields amplify collision energies by nearly an order of magnitude. For the 34 gravitational-wave events with high remnant
spins ($\chi_f > 0.7$), we compute the maximum achievable energies, finding that systems with $\chi_f \gtrsim 0.85$ and $M \gtrsim 100\,M_\odot$ can reach $E_{\mathrm{max}} \sim 10^{20}$~eV. Our results establish magnetized binary mergers, particularly black hole–
neutron star systems and postmerger black hole remnants formed in binary
neutron star coalescences, as promising sources of UHECRs and provide quantitative predictions linking gravitational-wave observables to particle acceleration efficiency.
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All authors Carlos H. Coimbra-Araujo, Rita C. Anjos, Jonas P. Pereira, Jaziel G. Coelho
Atmospheric and Oceanic Physics
Flexible generation of daily Earth system model projections across radiative forcing scenarios
Yu Huang, Sebastian Bathiany, Shangshang Yang et al. (+3 more)
Earth system model (ESM) projections of the
climate system's response to anthropogenic forcing are central to assess the impacts of
climate change and inform adaptation and mitigation policies. However, given their high computational cost, projections are only made for a limited set of standardized forcing scenarios with limited temporal extent, such as the Shared Socioeconomic Pathways (SSPs), the spatiotemporal resolution remains too low for direct impact assessments, and uncertainties cannot be comprehensively quantified. Recent data-driven models offer efficient and accurate high-resolution simulations for weather prediction, but cannot extrapolate to future greenhouse gas concentrations because they cannot capture the responses to unprecedented forcing, limiting their value for
climate change projections. Here, we combine response theory with a tailored generative machine learning framework to address this challenge. Our approach extracts the physical forced response to radiative forcing from monthly low-resolution ESM fields, and uses this response to guide a generative model to infer consistent daily global high-resolution temperature and precipitation projections. Our probabilistic approach generalizes across ESMs and provides long-term, bias-corrected responses to radiative forcing at high spatiotemporal resolution. It efficiently generates large ensembles needed for uncertainty quantification, effectively fills the gaps between existing SSPs, and readily extends
climate projections to 2300 and beyond. Our framework hence complements ESM projections by providing efficient, stable, and high spatiotemporal resolution long-term
climate projection ensembles across emission scenarios, enabling detailed impact assessment and exploration of long-term
climate commitment.
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All authors Yu Huang, Sebastian Bathiany, Shangshang Yang, Philipp Hess, Michael Aich, Niklas Boers
Mathematical Physics
On Leray's Theoreme de Structure for a weak solution to the Navier-Stokes equations: an improvement of the result
Paolo Maremonti
In this note we furnish a new result concerning the well known théorème de structure by Leray related to a weak solution to the Navier-Stokes equations. We are able to furnish a new estimate on the left endpoint of the unbounded interval of regularity.
Statistical Mechanics
Free-volume origin of diverging direct correlations in hard crystals: insights from an exact one-dimensional model
Alessandro Simon and Martin Oettel
Second order direct correlation functions in three-dimensional hard-sphere
crystals have much larger amplitudes (of the order of $1/n_{\mathrm{vac}}$ where $n_{\mathrm{vac}}$ is the vacancy concentration) and a more strongly structured spatial form of apparent shorter range than their
liquid-state counterparts. We separate the two underlying questions—why the correlations are large and why they have the form they do—using the exact one-dimensional Percus functional for hard rods. A periodic
crystal-like density is represented by Gaussian peaks with occupation probability $q=1-n_{\mathrm{vac}}$. The relevant thermodynamic quantity is the local insertion free volume $A(x)$. Its minimum can be written as $A_{\mathrm{min}} =\Delta_{\alpha a}+(1-\Delta_{\alpha a})n_{\mathrm{vac}}$, where $\Delta_{\alpha a}$ is the residual free volume at full occupation caused by finite localization (characterized by a width parameter $\alpha$) and
lattice spacing $a$. The first and second direct correlations therefore contain the singular dependences $c^{(1)}\sim\ln A_{\mathrm{min}} $ and $c^{(2)} \sim-1/A_{\mathrm{min}} $. The observed $1/n_{\mathrm{vac}}$ dependence is the vacancy-dominated limit $n_{\mathrm{vac}}\gg\Delta_{\alpha a}$, rather than the most general result. The spatial form of $c^{(2)}$ has a separate geometrical origin: the hard-rod weight functions select configurations in which exclusion intervals and their boundaries intersect regions of small free volume. This produces plateaus, edges, and localized ridges tied to the underlying periodic density. A numerical solution of the inhomogeneous Ornstein–Zernike equation shows how these singular direct correlations are redistributed in the total and pair correlations. The model provides a minimal free-volume explanation for both the magnitude and the
lattice-specific form of crystalline direct correlation functions.
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Soft Condensed Matter
Pressure and asymmetry govern the shape and stiffness of inflatables
Nathan Vani, Tom Joblin, Alejandro Ibarra et al. (+3 more)
Inflatables made of thin sheets constitute a lightweight, scalable alternative to conventional soft
robots. Since sheets are essentially inextensible while offering low resistance to bending, the shape of a straight tube should be trivially set by volume maximization. We show that networks of parallel tubes made from two sheets differing in stiffness defy this expectation as their global shape is governed by the binding angle at the junctions of adjacent tubes. Through this angle, the stiffness asymmetry induces a pressure-dependent curling and stiffening of the networks. Modeling a tube cross-section as two coupled rods, we quantitatively describe the geometry and mechanics of this new class of inflatables. Our model captures unexpected mechanical features such as a stiffness scaling as the square root of pressure and a contact-induced stiffening between neighboring tubes – challenging common assumptions on thin-sheet inflatables. Unlike prior work restricted to the high-pressure regime, the pressure-dependent description further enables multiprogrammable control over a continuous range of
curvatures. Discussing a variety of examples, we finally show that networks of asymmetric tubes are a versatile platform for functional shape-morphing objects.
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All authors Nathan Vani, Tom Joblin, Alejandro Ibarra, José Bico, Étienne Reyssat, Benoît Roman
Chemical Physics
Graph Neural Network Force Fields (GPTFF-mol) for Organic Molecules from Optimization Trajectories (OpenGEM26)
Yifan Huang, Fankai Xie, Jiangnan Zheng et al. (+3 more)
Density functional theory (DFT) serves as a reliable tool for atomistic molecular simulations, while machine learning potentials have become powerful complements to balance accuracy and efficiency. In this work, we release OpenGEM26 (Open Generated Ensemble of Molecules, 2026), a large-scale
dataset comprising 200,000 unique molecules and 4.4 million conformations composed of H, C, N, O, S and Cl with up to ten heavy atoms. All calculations are carried out at the {\omega}B97X-D/Def2-SVP and Def2-TZVP levels with dispersion corrections, and complete structural optimization trajectories and abundant non-
equilibrium structures are recorded. Statistical analyses confirm that this
dataset covers a broader conformational space than QM9 in terms of energy, bond lengths and bond angles. A graph neural network-based potential GPTFF-mol is trained using the new
dataset, achieving an energy mean absolute error of 16 meV/molecule, which is equivalent to 0.82meV/atom, and superior force prediction performance compared with ANI-2x. Validated by butane rotation and keto-enol tautomerization tests, the model accurately describes molecular dynamical behaviors and reaction barriers at distorted geometries. This work provides a high-quality resource and robust ML potential for efficient simulations of sulfur- and chlorine-containing organic molecules.
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All authors Yifan Huang, Fankai Xie, Jiangnan Zheng, Tenglong Lu, Sheng Meng, Miao Liu
Quantum Physics
A solution to 2-copy distillability of Werner states
Jinshi Fu, Li Gao and Sang-Jun Park
Entanglement distillation is a fundamental task in
quantum information theory. In this work, we prove that Werner states in arbitrary dimension are $2$-copy distillable if and only if they are $1$-copy distillable. This answers the longstanding open question of the $2$-copy distillability of Werner states. This is an important step on determining whether every non-positive partial transpose (NPT) state is distillable, which remains one of the central open problems in the field of
entanglement distillation.
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High Energy Astrophysical Phenomena
Importance and Science Outcomes from the first XSPECT/XPoSat Workshop
Anuj Nandi, Rwitika Chatterjee, V. P. Shyam Prakash et al. (+49 more)
This paper summarizes the science outcomes of the first Workshop on Data Analysis using observations from the XSPECT payload onboard the XPoSat, which brought together early-career researchers and experts to explore the instrument's scientific capabilities through lectures and hands-on analyses. Participants performed end-to-end data analysis, including calibration, spectral modeling, and timing studies, on seven sources comprising
Neutron Star Low-Mass X-ray Binaries,
pulsars, and Black Hole X-ray Binaries, demonstrating the instrument's scientific potential. The observations, obtained during the first year of XSPECT operations, together with in-house developed software, were provided to the participants, making them the first users outside the instrument team to analyze XSPECT data. For NS-LMXBs, Aql X-1 exhibited a classical Type-I X-ray burst, enabling constraints on the
stellar radius through spectral fitting. Sco X-1, observed across its complete Z-track, revealed systematic spectral
evolution driven by
accretion-rate fluctuations and disk-corona coupling, while Cir X-1 displayed orbital phase-dependent transitions between hard and soft states, reflecting changes in
accretion geometry. Among
accretion-powered
pulsars, GX 301-2 showed a double-peaked, energy-dependent pulse profile and strong iron fluorescence lines due to
stellar wind reprocessing, whereas Vela X-1 exhibited orbital phase-dependent absorption and steady coronal temperatures. Among BH-XRBs, Cyg X-1 transitioned from a hard to soft-intermediate state with increasing disk contribution and spectral softening, while Cyg X-3 remained in the intermediate state with multiple emission lines originating from a clumpy
stellar wind. The workshop outcomes highlight the scientific promise of XSPECT and the importance of collaborative training in maximizing the science from XSPECT and future Indian space astronomy missions.
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All authors Anuj Nandi, Rwitika Chatterjee, V. P. Shyam Prakash, Ankur Kushwaha, M. C. Ramadevi, Kiran M. Jayasurya, Vivek K. Agrawal, M. Varun, Karan Akbari, Arya Sudhakaran, Daneshwar Bhandari, Vishal Kale, Vishal Jadoliya, Suchismito Chattopadhyay, Sakshi Maurya, Swasthik Visakh S, Debasish Krishnatreya, M Dhamodhar Reddy, Akash Agarwal, Giridharan L., Meghamani Halder, Juris N. J., Athira Mohanan, P. Majumder, Arbind Pradhan, Deblina Lahiri, Abhishek Jhala, Garima Tyagi, Abhisek Tamang, Akshara S B, P Aromal, Sreetama Das Choudhury, Sunirmal Rana, Ajith Balu, Mary Bosco, Jeyaraman Ilangovan, Shivani Chaudhary, Bhranti Rao, Biyas Chowdhury, Joysankar Majumdar, Sanjeeva Rao Prattipati, Subhasish Das, Sandip Naskar, Swapnil Singh, Vaishali S, Koushal Vadodariya, Radhakrishna Vatedka, Anurag Tyagi, Sachin Narang, Prapti Mittal, Madhu K V, Brindavan Mahto
High Energy Astrophysical Phenomena
Rapid Orbital Decay of Supersoft X-Ray Source WX Cen: a Surrounding Circumbinary Disk
Zhi-Qiang Liu, Wei-Min Liu and Wen-Cong Chen
WX Cen is most likely a candidate of compact binary supersoft X-ray sources, which consists of a white
dwarf (WD) and a donor
star that fills the Roche lobe. Recently, this source was detected to be experiencing a rapid orbital decay at a rate of $\dot{P} =-(4.4\pm0.4)\times10^{-7}~ \rm days~\rm{yr}^{-1}$. According to the mass function and optical eclipses, the donor-
star mass can be constrained to be $0.41-0.44$, $0.47-0.50$, and $0.55-0.59~M_\odot$ when the WD mass is $0.7$, $0.9$, and $1.2~M_\odot$, respectively. The observed orbital period derivative cannot be produced by the angular momentum loss due to mass loss during the
accretion of the WD,
magnetic braking (MB) mechanisms, including standard MB, convection and rotation-enhanced MB, and anomalous MB prescriptions. We propose that the rapid orbital decay of WX Cen is caused by the
tidal torque that originates from the resonant interaction between the binary and a surrounding circumbinary (CB) disk. Detailed
stellar evolution models indicate that a WD binary with a $2.5 \times 10^{-7}~M_{\odot}$ CB disk can evolve toward a WX Cen-like system, which has an orbital period derivative of $\dot{P}=-4.0\times10^{-7}~ \rm days~\rm{yr}^{-1}$ and a relatively high mass-transfer rate of $5.3\times10^{-7}~M_\odot\rm yr^{-1}$ that can trigger a stable hydrogen burning process on the surface of the WD.
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High Energy Physics (Experiment)
Solar axion searches with RES-NOVA: projected sensitivity and first prototype limit
D. Alloni, G. Benato, P. Carniti et al. (+49 more)
RES-NOVA is a cryogenic experiment based on PbWO4 scintillating bolometers produced from archaeological lead, originally designed to detect coherent elastic
neutrino-
nucleus scattering (CEvNS) from
galactic core-collapse
supernovae. We show that the same high-density, high-Z absorbers and sub-keV energy resolution make RES-NOVA an appealing probe of
solar axions. We compute the expected signal from the Primakoff, ABC (atomic recombination and de-excitation, Bremsstrahlung, Compton), longitudinal-plasmon (LP), and 57Fe
nuclear-line components of the
solar axion flux, folded through the inverse-Primakoff and axioelectric detection channels in PbWO4, which probe the
axion couplings to
photons (g_a-gamma), electrons (g_ae), and nucleons (g_aN), respectively. We derive projected sensitivities for a 1 ton*y exposure of the RES-NOVA demonstrator in the (g_ae,g_a-gamma), (g_ae,g_aN), and (g_a-gamma,g_aN) planes. The projected reach in g_ae approaches that of XENONnT to within a factor of ~2, despite a background roughly four orders of magnitude higher, thanks to the large target mass, the high-Z enhancement of the axioelectric and inverse-Primakoff cross sections, and the sub-keV energy resolution. Because the inverse-Primakoff constraint on g_a-gamma relies on absorption rather than coherent conversion, it is independent of the
axion mass, unlike bounds from
magnetic helioscopes. We complement these projections with the first
solar-
axion exclusion limit obtained on real data with a 13 g PbWO4 prototype grown from archaeological lead, using a background-model-independent optimum-interval analysis. These results establish RES-NOVA as a promising multi-coupling probe of
solar axions, with simultaneous sensitivity to g_ae, g_a-gamma and g_aN that is complementary to existing helioscope and direct-detection searches.
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All authors D. Alloni, G. Benato, P. Carniti, M. Cataldo, L. Chen, M. Clemenza, M. Consonni, G. Croci, I. Dafinei, F.A. Danevich, J. De Miguel, C. de Vecchi, D. Di Martino, R. Elleboro, N. Ferreiro Iachellini, F. Ferroni, F. Filippini, V. Fonoll, S. Ghislandi, A. Giachero, M. Giannotti, L. Gironi, P. Gorla, C. Gotti, D.L. Helis, D.V. Kasperovych, V.V. Kobychev, A. Lella, G. Lucente, G. Marcucci, A. Melchiorre, A. Menegolli, S. Nisi, M. Musa, L. Pagnanini, L. Pattavina, G. Pessina, S. Pirro, S. Pozzi, M.C. Prata, A. Puiu, S. Quitadamo, M.P. Riccardi, M. Rossella, R. Rossini, E. Sala, F. Saliu, A. Salvini, V.I. Tretyak, L. Trombetta, D. Trotta, H. Yuan
Plasma Physics
Langmuir probe and infrared thermography measurements of wide and narrow heat flux profiles in the ST40 tokamak
T. Brewer, X. Zhang, C. Marsden et al. (+11 more)
Very narrow heat flux profiles have been observed on ST40 with decay lengths in the near scrape-off-layer (SOL) of $\lambda_{q,near}<$~1~mm in H-mode
plasmas. Measurements from divertor Langmuir probes are compared with an infrared (IR) thermography system for upper-single null diverted
plasmas in L-mode and ELM-free H-mode. SOL current to the grounded divertor targets is measured from the Langmuir probes with profiles exhibiting a similar exponential decay to $\lambda_{q,near}$ suggesting the near SOL heat flux is related to enhanced electron current to the divertor. Inclusion of electron current contributions to the heat flux transmission coefficient is crucial in capturing similar narrow profiles to those from the IR thermography system. Ongoing upgrades to ST40 will enable more investigations on SOL power decay lengths on inboard and outboard targets in double and single null configurations.
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All authors T. Brewer, X. Zhang, C. Marsden, A. Scarabosio, J. Bryant, P. F. Buxton, M. Fontana, T. Gray, N. Lopez, L. Martinelli, A. Rengle, E. J. C. Tinacba, E. Vekshina, H. V. Willett
Quantum Physics
Floquet Reservoir Engineering for Remote Logical Entanglement
Mingxing Yao and Aashish A. Clerk
Implementing controlled dissipative dynamics is a powerful approach for state preparation in a variety of contexts, including the preparation of remote entangled states. Here, we show that by going beyond the standard setting of time-independent dissipative dynamics, one can realize even more powerful non-
unitary protocols. We introduce dissipative Floquet protocols for stabilizing remote
entanglement of logical
qubits, where continuously-running dissipation is interleaved with a periodic sequence of
unitary gates. These protocols harness existing experimental capabilities, and overcome time-
entanglement limits that constrain standard approaches. They also implement an autonomous form of
entanglement distillation. We show how these protocols give enhanced protection against waveguide loss, and as an example, analyze a specific implementation using cat-
qubits and transmons in a superconducting
circuit.
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Statistical Mechanics
Thermal pseudo-transitions in a frustrated spin-pseudospin sawtooth chain
Onofre Rojas and Jozef Strečka
We present an exact analysis of a
spin–pseudospin X sawtooth chain that incorporates three distinct valence states of copper ions and serves as a minimal model for one-dimensional cuprates composed of corner-sharing copper triangles. The model includes
magnetic exchange and electrostatic coupling constants both along the base sites and between base and apex sites capturing the competition between
spin and charge degrees of freedom. Using the transfer-
matrix method, we derive exact expressions for the free energy and obtain an analytical condition defining the pseudo-critical line associated with pronounced thermodynamic anomalies. The ground-state analysis reveals, besides an
antiferromagnetic phase, three frustrated phases characterized by distinct residual
entropies. At finite temperatures, these zero-temperature phase boundaries evolve into narrow
entropy ridges signaling pseudo-transitions between the corresponding quasi-phases. The specific heat and the avoided-crossing scale exhibit sharp but continuous peaks at the pseudo-critical temperature, whereas the physical correlation length may be controlled by a different subleading
eigenvalue. Local correlation functions uncover a cooperative rearrangement from charge-dominated to magnetically correlated regimes. Our results demonstrate that the sawtooth geometry promotes frustration and short-range coherence leading to pronounced pseudo-transition behavior.
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Earth and Planetary Astrophysics
Magnetohydrodynamical opening of dust traps in protoplanetary disks
Sergey Khaibrakhmanov and Vitaly Akimkin
Observed ring-like structures in protoplanetary disks are often interpreted as local pressure maxima, which induce efficient
dust concentration. We revisit this paradigm, considering the effect of the large-scale
magnetic field stresses on the gas rotation speed. Our simulations show that the
magnetic field can be dynamically strong and cause $1-2$% deviation from the Keplerian rotation at the periphery of a typical turbulent disk with
dust grains of size $> 1\,\mu$m. This effect increases the inward drift speed of large grains characterized by Stokes number of $0.01-0.1$ by up to two times in our simulations. Importantly, such MHD deviation from the Keplerian rotation does not depend on the local gas pressure gradient and leads to drift towards the
star only. The fast drift induced by this effect can cancel out the outward drift caused by the positive pressure gradient at the inner edge of a ring and open up the
dust trap. For the disks with
turbulence parameter $\alpha=10^{-3}$, this effect appears in the rings with a half-width of $10$ au and a density contrast up to $60$% ($200$% for $\alpha=10^{-2}$). Thus, the presence of a large-scale
magnetic field in protoplanetary disks either completely prevents or imposes stricter conditions for
dust accumulation and the onset of the streaming instability in the density rings in protoplanetary disks.
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Physics Education
Embodied inquiry with AI as facilitator: an exploratory case study
Eugenio Tufino and Paola Damiani
Generative AI is entering science education at a time when the
embodied education community is asking what such systems cannot do. Rather than asking whether AI can understand the body, this exploratory case study asks where a
language-based AI can stand within an inquiry activity without displacing
embodied experience. University students in a Master's course in physics education investigated the statics of fluids following the ISLE approach (Investigative Science Learning Environment) in a two-phase design: students first built the buoyancy model with their own hands, without AI; a purpose-configured AI assistant then facilitated the application of the model to a new phenomenon. We discuss what a
language-based facilitator cannot reach and the value of a design in which AI complements
embodied inquiry rather than replacing it.
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Lattice Field Theory
Perturbative quantum electrodynamics with generalized domain wall fermions
Matteo Di Carlo and Antonin Portelli
In this paper we derive the expansion of the generalized domain-wall
fermion Dirac operator including electromagnetic corrections up to $\mathcal{O}(e^2)$, which are relevant for
lattice computations of radiative corrections to hadronic processes with
chiral fermions. In the generalized formulation of the domain-wall fermionic QCD+QED action, physical
quark fields are related to the corresponding five-dimensional fields in a way which depends on the (QCD+QED) gauge links, generating extra contact terms when expanding correlation functions with respect to the electric charge. We re-derive the known first-order correction using a background-field approach and, at second order, obtain new local operator insertions (seagull vertices) required for gauge covariant calculations.
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Instrumentation and Detectors
Front End Amplifiers for Simultaneous Dual Readout of SiPM Sensors
Lucas Finazzi, Felipe Soriano, Leandro Gagliardi et al. (+4 more)
In this work, we present two fully open Analog Front End (AFE) designs for the simultaneous readout of the standard and fast outputs of ONSemi MicroFC-10035 Silicon Photomultipliers and report their main figure-of-merit parameters. The standard output AFE has a 1 p.e. amplitude of $(394 \pm 1)$ mV, which results in a Signal-to-Noise ratio of 30 dB. In addition, the fast AFE has a rise time of $(1.3\pm 0.1)$ ns and a median electronic jitter of $34^{+7}_{-5}$ ps, resulting in an excellent timing performance. Using these amplifiers for simultaneous dual readout, we demonstrate a proof-of-concept application, in which fast output timing information is used to suppress correlated noise events or pileup events present in the standard output charge measurements. This suppression results in a reduction of non-
prompt correlated noise (delayed crosstalks and afterpulses) in dark conditions and an increase up to $\sim$14 in single
photon discrimination under a continuous incident
photon rate of 7.8 MHz/mm$^2$. These results show that dual SiPM readout provides a practical way to remove correlated noise or pileup contamination in standard output charge measurements on an event-by-event basis.
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All authors Lucas Finazzi, Felipe Soriano, Leandro Gagliardi, Alexis Luszczak, Hugo Mériaux, Gabriel Sanca, Federico Golmar
Quantum Physics
Efficient classical simulation of large-scale unitary cluster Jastrow circuits
Hrishikesh Belagali, Thomas Van Camp, R. Pradeep et al. (+3 more)
Recent experiments on
quantum computers have challenged the limits of classical computation in chemistry, simulating ground states of strongly correlated molecules. Many of these experiments have utilized the
unitary cluster Jastrow ansatz, a
quantum circuit inspired by the
unitary coupled cluster ansatz that can be tailored to current
quantum hardware. Notably, the largest experiment in Sci. Adv. 11, 25 (2025) executed a
quantum circuit with 77
qubits and 10,570 gates on an IBM
quantum computer and performed classical post-processing with up to 6400 nodes on Fugaku to compute ground state energies better than Hartree-Fock. In this work, we present a
polynomial time classical
algorithm to compute the energy of any single-layer
unitary cluster Jastrow
circuit, independent of locality constraints for
quantum hardware. Our
algorithm can reproduce the largest experiment from Sci. Adv. 11, 25 (2025) in less than a minute on a laptop, and through
circuit optimization enabled by fast simulation we achieve a lower ground state energy than the experiment.
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All authors Hrishikesh Belagali, Thomas Van Camp, R. Pradeep, Sourin Das, Namit Anand, Ryan LaRose
Cosmology and Nongalactic Astrophysics
Web-Halo Model Peak-Background Split (WHM-PBS): halo bias as a distribution, not a number
Samuel Brieden and Alexander Tipp
We present the Web-
Halo Model Peak-Background Split (WHM-PBS), an analytic theory in which the large-scale bias of a dark-matter
halo is inherited from its
cosmic-web environment. Building on the Web-
Halo Model, we use the Shen et al. moving barriers for ellipsoidal collapse generating the web hierarchy in which every
halo sits inside a host filament, itself inside a sheet. Combined with the peak-background split, this picture replaces the deterministic bias-mass relation $b(M_h)$ with the bias of the host environment, averaged over the conditional mass function. As a result,
halo bias $b(M_h)$ is no longer a number but a strongly skewed distribution. In this work we make use of this distribution in three different ways: as (i) a physically motivated prior on bias relations, (ii) a prediction on
halo stochasticity, and (iii) a framework for assembly bias models. Regarding (i) we find that the density bias relations $b_2(b_1)$ and $b_3(b_1)$ stay tight, while the
tidal bias $b_{s^2}(b_1)$ shows significant scatter, as found in $N$-body simulations. Regarding (ii), once including
halo exclusion, our model reproduces the super- to sub-Poisson shot-noise trend of Baldauf et al. which we convert into a prior band on the EFT stochasticity amplitude parameters. Finally, regarding (iii) in the density sector it explains the bias-concentration-correlation inversion of Paranjape et al. at the characteristic mass ($M_\mathrm{h}\simeq 1.7\times 10^{13}\,h^{-1} M_\odot$), with no parameter tuned to assembly bias. We apply the resulting priors on synthetic data, demonstrating that the WHM-PBS priors mitigate projection effects arising when all nuisance parameters are varied freely, while fixed priors may fail severely. The code to reproduce our results is publicly available at https://github.com/SamuelBrieden/whmpbs.git.
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Quantum Physics
Quasiparticle-induced transitions in a fluxonium qubit
Maksim Litskevich, Kesavan Manivannan, Benjamin Byrd et al. (+4 more)
Quasiparticles are a prominent decoherence source in superconducting
qubits, but their effects are notoriously difficult to isolate in fluxonium. Unlike the transmon, fluxonium is insensitive to offset charge, precluding charge-parity detection of quasiparticle tunneling. We address this challenge by measuring the excitation and de-excitation rates in a fluxonium
qubit under controlled on-chip quasiparticle injection and isolating the quasiparticle-induced contribution by subtracting the background transition rates. We show that to accurately model the external
magnetic flux dependence of the quasiparticle-induced transition rates, it is necessary to account for the superconducting gap asymmetry across the Josephson junctions. A comparison between theory and experiment constrains the relative quasiparticle densities in the small junction and the junction array and helps explain previously reported discrepancies between the bounds on the quasiparticle densities inferred for these two
circuit elements.
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All authors Maksim Litskevich, Kesavan Manivannan, Benjamin Byrd, Pavel D. Kurilovich, Vladislav D. Kurilovich, Gianluigi Catelani, Ivan V. Pechenezhskiy
Classical Physics
Spatiotemporal Vortex Rings Induced by Spatiotemporal Coupling
Zhiling Zhou, Wei Zhong, Tong Fu et al. (+4 more)
Vortices and
vortex rings are topological structures that arise in various physical systems. However, the generation of spatiotemporal
vortices (STVs) and
vortex rings (STVRs) has so far relied on complex, often active wavefront modulation. We theoretically and experimentally demonstrate that spatiotemporal coupling can drive unstructured wave packets to form
vortices upon scattering from simple obstacles. The resulting STVs and STVRs possess controllable topological charges and excellent propagation stability. These findings reveal a fundamental mechanism for spatiotemporal singularity formation and provide a universal route to structured-wave generation.
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All authors Zhiling Zhou, Wei Zhong, Tong Fu, Wanyue Xiao, Zhongming Gu, Jie Zhu, Shubo Wang