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Physics

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Thursday 20 August

Atmospheric and Oceanic Physics

GOES-East full-disk AI nowcasting of cloud evolution in observation space

Dhamma Kimpara, Omid Bagheri, Ivette Hernandez Banos et al. (+2 more)

Clouds affect aviation, solar energy, remote sensing, and storm prediction, yet they remain among the hardest atmospheric features to forecast, particularly at convective scales. Because clouds are shaped by processes spanning a wide range of space and time scales, numerical weather prediction, extrapolation methods, and existing machine learning (ML) approaches are each limited by some combination of accuracy, domain size, and temporal resolution. We present DOP+, an ML approach for clouds that forecasts GOES-East full-disk infrared brightness temperatures by extending direct observation prediction (DOP) with conditioning on meteorological fields. The domain covers tropical, midlatitude, and marine regimes across $\sim 10^8 ~ km^2$, roughly a fifth of Earth's surface. DOP+ forecasts cloud evolution at 10-minute resolution and outperforms persistence, synoptic-scale NWP, and a pure DOP baseline across 0-6 h lead times in fractions skill score and mean absolute error skill score. Convective structure is retained out to 2-3 h. DOP+ thus achieves a state-of-the-art combination of accuracy, temporal resolution, and spatial coverage. Our work lays the foundation for fully global cloud nowcasting at convective timescales.
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All authors Dhamma Kimpara, Omid Bagheri, Ivette Hernandez Banos, Byoung-Joo Jung, Chris Snyder

Superconductivity

A non-local power-law baseline for transient flux penetration in YBCO films: parameter degeneracy and constitutive limitations

O. A. Hernández-Flores, C. Romero-Salazar and F. Pérez-Rodríguez

We assess whether a non-local thin-film model with a bounded, constant-exponent power law can reproduce high-speed magneto-optical measurements of transient flux penetration in a $3\times3$~mm$^2$ YBa$_2$Cu$_3$O$_{7-\delta}$ film. The model is solved forward in physical units and used as a controlled constitutive baseline. The critical sheet current is constrained by the final penetration geometry, while the criterion field and creep exponent are constrained by the turnover and relaxation times. The calibration reveals an intrinsic degeneracy: the turnover time depends primarily on the product of the criterion field and saturation parameter, equivalently on the saturated sheet resistivity, so these quantities cannot be identified independently. After parameterizing this degeneracy, the model captures a guarded-current turnover near 22~ms, a relaxation constant of 41.2~ms compared with the measured 37.5 and 43.7~ms, and a late maximum approximately 0.92~mm from the film edge. The amplitude remains discrepant: the calculated transient maximum is $1.90J_{c0}$ and the peak-to-225-ms ratio is 2.13, compared with the reported 1.20. This excess persists under changes in the creep exponent, the degenerate parameter direction, the Kim field dependence, and mesh resolution. Matching the measured ratio through the criterion field would require a value about three orders of magnitude below the conventional scale, while spatial exclusion sufficient to match it would remove the edge peak itself. We also decompose the electric field into irrotational and solenoidal parts and quantify the boundary layer where spectral and finite-difference forms of Faraday's law disagree. The results establish a reproducible non-local power-law baseline and identify limitations of the bounded, constant-exponent constitutive family rather than of non-local thin-film electrodynamics.
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Soft Condensed Matter

Reversing strain deformations probe mechanisms for enhanced segmental mobility of polymer glasses

Kelly Hebert and M.D. Ediger

Optical probe reorientation measurements were performed to monitor changes in segmental dynamics resulting from the nonlinear deformation of a polymer glass. Segmental dynamics were monitored in a poly(methyl methacrylate) glass near Tg before and after a series of reversing deformations in which the sample was extended at constant strain rate and then allowed to retract back to zero stress at constant strain rate. Evidence of a rejuvenation mechanism, as quantified by a departure of the segmental dynamics from the quiescent aging dynamics after the reversing deformation, is observed for deformations which reach 60% of the yield strain or greater. By this measure, a saturation of the rejuvenation mechanism is not observed until at least five times the yield strain. For comparison, purely mechanical measurements of rejuvenation, based upon the reduction of the yield stress in a subsequent deformation, were also performed. These purely mechanical experiments show broad qualitative agreement with the probe reorientation experiments, but quantitatively differ in the pre-yield regime. The results are discussed in the context of recent theoretical approaches and simulations which provide a molecular-level description of polymer glass deformation.
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Superconductivity

Perspectives on Magnetic/Superconductor Hybrid Systems: Long-range Electromagnetic Phenomena Induced by Proximity Effect and Interfacial Spin-orbit Coupling

S. V. Mironov, A. S. Mel'nikov and A. I. Buzdin

In this Perspective we review recent achievements in physics and applications of hybrid superconductor-ferromagnet structures. In particular, we focus on the manifestations of the electromagnetic phenomena in these systems originating from the response of the induced superconducting correlations modified by the exchange field and additional effects coming from the interface Rashba-type spin-orbit coupling. The review includes the long-range electromagnetic proximity effect and related modification of magnetic textures, spontaneous currents, properties of vortex matter and its interaction with magnetic ordering, spin-galvanic, photogalvanic and nonreciprocal transport phenomena in exemplary hybrid systems. We also present our views on the future development of this field including both the theoretical challenges and promising opportunities for fundamental experiments.
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High Energy Physics (Theory)

Supersymmetric Virasoro Minimal Strings: Unified Perturbative and Non-Perturbative Treatment

Clifford V. Johnson

There are four known ${N}{=}1$ supersymmetric Virasoro minimal string theories, naturally coming in two pairs and labeled as 0A$^\pm$ and 0B$^\pm$. We observe here that all four are naturally described in terms of solutions of an ordinary differential equation that describes certain random matrix models with positive spectra. Two new additional 0A$^-$ theories, which are unorientable, are naturally described by the framework. The formulation allows for simple computation of all perturbative amplitudes, and provides complete non-perturbative information as well. Our approach makes it clear why type 0A$^-$ can be deformed to include a gas of Ramond vertex insertions, which we fully describe, while type 0A$^+$ cannot. While it is known that the $c\rightarrow\infty$ limit reduces the 0A$^-$ and 0B$^-$ models to the familiar 0A and 0B JT supergravities of Stanford and Witten, the same limit for the plus pair reduces to non-perturbative completions of ordinary JT gravity, one of which is known. Large families of ${N}{=}2$ and ${N}{=}4$ supersymmetric analogues of the Virasoro minimal strings are also proposed and explored in detail, using the same approach.
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Materials Science

Interplay of nonrelativistic and relativistic spin splittings in altermagnets

Daegeun Jo, Peter M. Oppeneer and Mohsen Yarmohammadi

Despite their compensated magnetic moments, altermagnets (AMs) exhibit nonrelativistic spin splitting (NRSS) that offers routes to spintronic functionality without relying on relativistic spin-orbit coupling. However, how NRSS influences relativistic phenomena remains largely unexplored. Here we show that NRSS plays a crucial role in reshaping the Rashba effect in AMs with broken inversion symmetry. Using a tight-binding model, we demonstrate that Rashba spin splitting, whose magnitude is typically limited by the strength of spin-orbit coupling, is governed by NRSS energy scales. The resulting Rashba bands combined with NRSS generate anomalously large charge-to-spin conversion with a Néel-vector-tunable spin polarization. First-principles calculations for the noncentrosymmetric AM GdAlSi corroborate the emergence of these effects in a real system. Our results reveal the interplay between nonrelativistic and relativistic effects in AMs and identify them as fertile platforms for spin-orbitronic applications.
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Quantum Gases

Photon-mediated thermodynamics and density fluctuations in an ensemble of laser-cooled Cesium atoms

Arnab Ghosh, Inderpreet Kaur, Hemant Yadav et al. (+5 more)

We present an experimental study of detuning-dependent properties of a laser-cooled cesium cloud in a magneto-optical trap. Fluorescence images are used to extract the cloud size, shot-to-shot width fluctuations, optical depth, density profiles, and spatial density fluctuation spectra as the trapping-laser detuning is varied. Near resonance, the cloud exhibits larger spatial extent, increased width fluctuations, higher optical depth, and enhanced density-fluctuation power, while larger detunings produce a more reproducible and spatially confined cloud. The measured density profiles are analysed phenomenologically using a generalized Lane-Emden model with a polytropic equation of state, yielding detuning-dependent effective fit parameters in a weak-interaction regime. Power-spectrum and autocorrelation analyses reveal reproducible scale-dependent density correlations. The results provide a quantitative characterization of detuning-dependent radiative and collective effects in a cesium MOT and establish a basis for future measurements that can more directly test nonequilibrium transport and photon-mediated interaction models.
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All authors Arnab Ghosh, Inderpreet Kaur, Hemant Yadav, Shiva Kant Dwivedi, R Shanmukesh, Mithun Thudiyangal, Matthew J. Davis, Bodhaditya Santra

Nuclear Theory

Thermodynamically Consistent Merging of Multidimensional QCD Equations of State

Prachi Garella, Yumu Yang, Musa R. Khan et al. (+7 more)

We present a thermodynamically consistent framework for merging complementary models into a multidimensional QCD equation of state. An internal mixing variable is determined by minimizing a single grand potential at fixed temperature and baryon chemical potential, ensuring thermodynamic consistency and stability. Interactions between the components allow for a crossover, a critical endpoint, and a first-order transition. As a proof of principle, we merge a quantum van der Waals hadron-resonance-gas model with a holographic Einstein–Maxwell–Dilaton model. The resulting equation of state reproduces the appropriate description in each regime, agrees well with available lattice-QCD results, and is suitable for heavy-ion phenomenology over a broad range of temperature and baryon chemical potential.
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All authors Prachi Garella, Yumu Yang, Musa R. Khan, Tulio E. Restrepo, Joaquin Grefa, Johannes Jahan, Mauricio Hippert, Jorge Noronha, Claudia Ratti, Romulo Rougemont

Physics Education

Large Scale AI Grading of Handwritten Physics Assessments: Score Agreement and Olympiad Team Selection Outcomes

Praveen Pathak, Siddharth Tiwary, Charudatt Kadolkar et al. (+4 more)

Multimodal AI can read handwritten physics solutions, but high-stakes grading requires agreement with official scores and outcomes. This study evaluated GPT-5.5-based grading on 10364 scanned pages from 520 handwritten submissions by 416 unique candidates or students across three assessments: a national Physics Olympiad theory examination, the final Olympiad selection camp with theory and experiment components, and a university quantum-mechanics examination. Each submission was graded twice by AI using the official rubrics. The second round used revised page-by-page and evidence-location instructions developed after first-round disagreement analysis. During grading, AI did not see official human marks or AI–human comparisons. Total-score correlations with official marks were high (0.91–0.97). For the final Olympiad selection, AI recovered the same five-student team as official grading. The second round improved aggregate question-part agreement, especially where first-round disagreements were larger. The main difficulty remained exact partial-credit grading, especially in experimental work. Reliable AI grading therefore depends on detailed rubrics and should be used as a second reader or audit tool under examiner control.
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All authors Praveen Pathak, Siddharth Tiwary, Charudatt Kadolkar, Vijay Singh, David Rakestraw, Shirish Pathare, Anwesh Mazumdar

Mesoscale and Nanoscale Physics

$\mathcal{PT}$ and anti-$\mathcal{PT}$ phase transitions in a trimerized Su–Schrieffer–Heeger chain with nonreciprocal Rashba spin-orbit coupling

Milad Jangjan, Linhu Li, Longwen Zhou et al. (+1 more)

We theoretically investigate a one-dimensional trimerized Su–Schrieffer–Heeger chain with three sublattices per unit cell subjected to a nonreciprocal Rashba spin-orbit coupling. Invoking a spin-flip symmetry, the non-Hermitian Hamiltonian decomposes into two independent spin sectors, enabling a spin-resolved analysis of non-Hermitian skin effects and system symmetries. We identify a rich phase diagram consisting of four bulk phases and two edge-state phases. The bulk phases include fully $\mathcal{PT}$-unbroken (real-spectrum) and fully anti-$\mathcal{PT}$-unbroken (imaginary-spectrum) regimes, as well as two mixed phases where one band remains on the real or imaginary axis while the other two form complex-conjugate pairs. The two edge-state phases correspond to topological edge modes with either $\mathcal{PT}$-unbroken (real) or anti-$\mathcal{PT}$-unbroken (imaginary) energies. Using non-Bloch band theory and Cardano's method, we derive closed-form expressions for phase boundaries and establish the bulk-edge correspondence for each spin sector. Calculations of Berry phase and directional inverse participation ratios confirm our analytical predictions. Our results provide a minimal platform for realizing spin-resolved non-Hermitian topology and edge-selective symmetry preservation, in which the bulk and edge states belong to distinct symmetry classes.
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All authors Milad Jangjan, Linhu Li, Longwen Zhou, Mir Vahid Hosseini

Medical Physics

An integrated diffusion-weighted imaging processing and interpretation platform for MR-guided radiotherapy

Yunxiang Li, Yan Dai, Yen-Peng Liao et al. (+3 more)

Background: Magnetic resonance imaging-guided linear accelerators (MR-Linacs) allow diffusion-weighted imaging (DWI) to be acquired at every treatment fraction, but converting these low-signal-to-noise-ratio acquisitions into clinical decisions requires both reliable quantitative processing and an interpretation that reconciles a scattered and often contradictory literature. Purpose: To describe and evaluate an integrated, web-based platform that carries raw MR-Linac DWI to a structured, literature-grounded clinical interpretation, and to assess its retrieval-augmented generation (RAG) interpretation module by independent expert rating. Methods: The platform couples a deep-learning processing pipeline, comprising distortion correction, denoising, and intravoxel incoherent motion (IVIM)/apparent diffusion coefficient (ADC) fitting, with longitudinal region-of-interest analysis and a RAG interpretation agent. The agent reasons over a two-layer knowledge base of curated publications (a structured catalog index plus line-indexed full text), delegates arithmetic to deterministic tools, and is designed to trace each statement to a source document, section, and line range. One medical physicist and one physician independently rated the agent's reports for nine longitudinal glioblastoma cases on a 1-5 scale across three metrics: clinical-reasoning soundness, literature-citation quality, and overall clinical utility. Results: Across 54 ratings, the pooled mean was 4.65 +/- 0.80, with 93% of ratings >= 4; metric means were 4.6 (reasoning), 4.5 (citation), and 4.8 (utility), and raters agreed within one point on 85% of paired ratings. Conclusions: A single platform can integrate MR-Linac DWI post-processing with traceable, expert-evaluated clinical interpretation, while highlighting the safeguards needed to verify LLM-generated reasoning in radiation oncology.
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All authors Yunxiang Li, Yan Dai, Yen-Peng Liao, Jie Deng, Jill B De Vis, You Zhang

Adaptation and Self-Organizing Systems

Self-organizing Chimera States in Adaptive Networks

Felix Augustsson, Rok Cestnik, Matthias Wolfrum et al. (+3 more)

We propose a minimal adaptive network model with product-form coupling that reduces dimensionality while capturing key features of synaptic plasticity. The system spontaneously self-organizes into adaptive chimera states, where identical oscillators separate into synchronized and desynchronized groups through adaptive weight dynamics. These adaptive chimeras organize into branches with fixed coherent cluster fraction and exhibit transitions between stationary, breathing, and chaotic collective dynamics, revealing a collective bifurcation structure. Crucially, the resulting attractor landscape is highly multistable: repeated cluster reorganizations generate distinct dynamical pathways that coexist within the same parameter regime and depend sensitively on initial conditions.
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All authors Felix Augustsson, Rok Cestnik, Matthias Wolfrum, Christian Bick, Serhiy Yanchuk, Erik Andreas Martens

Materials Science

Revealing the Role of Confined Molecular H$_2$ in the Passivation of Defective Silicon Using First-Principles Simulations

Hania Azzam, Tobias Binninger, Benedikt Fischer et al. (+2 more)

The passivation of silicon dangling bonds by hydrogen is a crucial requirement for silicon-based optoelectronic technology, especially for solar cells. Recent experiments on intense light soaking of silicon heterojunction solar cells unveiled interesting dynamical aspects of hydrogen passivation that are linked to Si-H bond breaking and repassivation. These processes take place predominantly in porous regions near the amorphous/crystalline interface, where hydrogen can exist in molecular form. This work addresses the question of whether molecular H$_2$ directly participates in Si-H depassivation and repassivation. Using density functional theory, we calculate and compare formation energies of point defects, multivacancy cavities and the Si(100) surface to identify relevant passivated and depassivated states. Furthermore, we employ nudged elastic band calculations to determine the activation barriers of the corresponding pathways. We find that sufficient local free volume enables a direct double-H pathway for depassivation through the formation of confined molecular H$_2$. Despite involving the breaking of two Si-H bonds, the double-H process can be energetically and kinetically competitive with the single-H process and can exhibit a reverse repassivation barrier as low as $0.15\,$eV under p-type conditions. These findings provide a plausible atomistic explanation for passivation recovery during light soaking and illuminated annealing in porous regions near amorphous/crystalline silicon interfaces.
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All authors Hania Azzam, Tobias Binninger, Benedikt Fischer, Uwe Rau, Michael Eikerling

High Energy Physics (Phenomenology)

Probing Non-Holomorphic Modular $A_4$ Double Seesaw: Signatures in Neutrino Oscillation Experiments and Implications for Leptogenesis

Pratik Adarsh, Dinesh Kumar Singha, Mitesh Kumar Behera et al. (+1 more)

We realize the double seesaw mechanism within a non-holomorphic modular $A_4$ framework by extending the Standard Model with three generations of right-handed neutrinos (RHNs), three left-handed sterile neutrino fields, and an $A_4$-singlet scalar. The modular construction forbids a bare Majorana mass term for the RHNs and realizes the hierarchy required for the double seesaw, with RHN masses induced through the heavier sterile neutrino sector. A comprehensive scan of the modular parameter space yields viable normal ordering solutions consistent with current neutrino oscillation data. We further examine their testability at DUNE, T2HK, and JUNO. DUNE and T2HK strongly probe the atmospheric mixing parameters and constrain the allowed model space, while JUNO provides complementary precision sensitivity to the solar mixing angle and mass-squared splitting. The oscillation compatible points also determine the induced RHN spectrum and complex Yukawa textures relevant for thermal leptogenesis. For a representative unflavored benchmark in the strong-washout regime, numerical Boltzmann evolution including decays and inverse decays yields $Y_{\Delta B}\simeq8.11\times10^{-11}$, close to the observed baryon asymmetry. The allowed parameter space also admits an $N_1$-dominated two-flavor thermal leptogenesis realization with a hierarchical, non-resonant RHN spectrum. Our results establish the non-holomorphic modular $A_4$ double seesaw as a predictive framework linking low-energy neutrino phenomenology and thermal leptogenesis, with oscillation predictions directly testable at forthcoming precision neutrino experiments.
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All authors Pratik Adarsh, Dinesh Kumar Singha, Mitesh Kumar Behera, Sudhanwa Patra

Applied Physics

Electrostatic Influence of Diamond Heat-Spreaders on GaN FET Performance

Lincoln Hogan, MD Mazharul Islam and Ahmedullah Aziz

Diamond, with its exceptional thermal conductivity, is widely explored as a heat spreader to improve thermal management in GaN-based power and RF electronics. In this work, we use Sentaurus TCAD to model AlGaN/GaN HEMTs with integrated diamond heat spreaders, incorporating advanced physical models such as thermal boundary resistance (TBR) and temperature-dependent bandgap narrowing. While diamond significantly enhances heat dissipation, our simulations reveal an important but often overlooked tradeoff: electrostatic modulation at the diamond and semiconductor interface. We initially modeled a p-GaN HEMT with all-around diamond integration and show agreement to the experimentally reported electrothermal benefits of diamond heat spreader integration. However, we observe strong band bending at the diamond/GaN interface alongside electric field generation and increased valence band energy in diamond. As a result, an interfacial hole accumulation region forms at the GaN surface, altering vertical transport and hindering current injection which prevents high on-state current. These results indicate that although diamond improves thermal performance, it can also actively influence the electrostatics of the transistor. To address both the elevated TBR and the undesired interfacial band bending, we propose the incorporation of an engineered interlayer. Building on our Sentaurus TCAD results, we develop a Silvaco TCAD TLM test structure to characterize the extent of the hole accumulation region formation and give insight to future studies on mitigation through interlayer development.
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High Energy Physics (Experiment)

Measurement of the muon flux at SNOLAB using the DEAP-3600 experiment

DEAP Collaboration: P. Adhikari, M. Alpízar-Venegas, P.-A. Amaudruz et al. (+115 more)

A direct measurement of the muon flux at SNOLAB is performed using the DEAP-3600 experiment, located 2 km underground at SNOLAB near Sudbury, Canada. Primarily designed for the direct detection of weakly interacting massive particles (WIMPs), a dark matter candidate, DEAP-3600 consists of an inner spherical acrylic vessel containing a liquid argon target; this vessel is enclosed within a steel shell which is submerged in an instrumented water tank, serving as a muon veto for the dark matter search. The muon flux measurement is performed using a cut-and-count analysis of events observed in the muon veto detector and of events which are coincident between the muon veto and the liquid argon target. The requirement that muons traverse both the water and liquid argon minimizes instrumental backgrounds and systematic uncertainties. Using data collected from November 2016 to March 2020, the muon flux is measured by this coincidence analysis to be $(3.71 \pm 0.25_{\textrm{stat}} \pm 0.09_{\textrm{sys}}) \times 10^{-10}\, \mu/$cm$^2$/s. The standalone measurement using muon veto data only is compatible within uncertainties. Both measurements agree with the previous result by the SNO experiment and with simulations carried out using the MUTE software. These results provide an important benchmark for future rare-event searches at the SNOLAB facility.
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All authors DEAP Collaboration: P. Adhikari, M. Alpízar-Venegas, P.-A. Amaudruz, D. J. Auty, M. Batygov, B. Beltran, M. A. Bigentini, C. E. Bina, W. Bonivento, M. G. Boulay, J. F. Bueno, M. Cadeddu, B. Cai, M. Cárdenas-Montes, N. Cargioli, S. Cavuoti, S. Choudhary, B. T. Cleveland, R. Crampton, E. Darling, S. Daugherty, P. Di Stefano, G. Dolganov, L. Doria, F. A. Duncan, M. Dunford, E. Ellingwood, A. Erlandson, S. S. Farahani, N. Fatemighomi, L. Ferro, G. Fiorillo, R. J. Ford, A. Garai, P. García Abia, S. Garg, P. Giampa, A. Giménez-Alcázar, D. Goeldi, P. Gorel, K. Graham, A. L. Hallin, M. Hamstra, S. Haskins, J. Hu, J. Hucker, D. Huff, T. Hugues, A. Ilyasov, B. Jigmeddorj, C. J. Jillings, G. Kaur, A. Kemp, M. Khoshraftar Yazdi, G. Killaire, M. Kuźniak, F. La Zia, M. Lai, S. Langrock, B. Lehnert, M. Lissia, L. Luzzi, I. Machulin, S. MacKenzie, A. Maru, J. Mason, A. B. McDonald, T. McElroy, J. B. McLaughlin, C. Mielnichuk, L. Mirasola, S. Mohanty, A. Moharana, J. Monroe, A. Murray, M. Needs, C. Ng, G. Nieradka, G. Oliviéro, M. Olszewski, S. Pal, D. Papi, B. Park, R. Pavarani, M. Perry, V. Pesudo, T. R. Pollmann, F. Rad, C. Rethmeier, F. Retière, L. Roszkowski, R. Santorelli, F. G. Schuckman II, M. Sestu, S. Seth, V. Shalamova, P. Skensved, T. Smirnova, K. Sobotkiewich, T. Sonley, J. Sosiak, J. Soukup, R. Stainforth, M. Stringer, J. Tang, P. Taylor, C. Tierney, P. Tokareva, S. Tullio, R. Turcotte-Tardif, E. Vázquez-Jáuregui, G. Vera Díaz, S. Viel, B. Vyas, J. Walding, M. Ward, S. Westerdale, R. Wormington

Chemical Physics

Real-time ESR tracking for sub-micron 3D magnetic mapping with VB- quantum sensors in hexagonal boron nitride

Jefferson A. O. Galindo, Edwin D. C. Sanchez, Cecília L. A. V. Campos et al. (+6 more)

The discovery of spin-dependent luminescent properties of negatively charged boron-vacancy centers ($V^-_B$) in hexagonal boron nitride (hBN) enabled a new platform for quantum sensing with van der Waals materials. Particularly, the possibility of performing optically detected magnetic resonance (ODMR) for determining the electron spin resonance (ESR) frequencies of hBN color centers became a strong tool for quantum sensing of magnetic fields with submicrometric resolution. However, due to low ODMR contrast, current techniques proposed for mapping DC magnetic fields require hours of integration to obtain a magnetic image of a micron-sized region. In this work, we report the implementation of a frequency-tracking approach for real-time monitoring of ESR frequencies of localized $V^-_B$ centers in hBN. With this technique, magnetic field monitoring was used to map the field pattern generated by a micron-sized conical magnetic tip in only a few minutes. By controlling the magnetic sample's position relative to the quantum sensor, three-dimensional magnetic mapping of the field was achieved with diffraction-limited resolution and shot-noise-limited sensitivity of 54 $\mu$T$/\sqrt{\text{Hz}}$. Magnetic field gradients of 3.6 $\pm$ 0.2 $\mu$T/nm were measured with our system, in which a maximum detected field rate of 6 mT/s was achieved. The results of this study establish spin resonance frequency-tracking as a viable technique and fast method for minute-scale magnetic imaging, reducing acquisition times by at least one order of magnitude if compared to conventional techniques.
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All authors Jefferson A. O. Galindo, Edwin D. C. Sanchez, Cecília L. A. V. Campos, Allison R. Pessoa, Hugo A. D. Correia, José D. M. de Lima, Klaus Krambrock, Leonardo de S. Menezes, Anderson M. Amaral

Mesoscale and Nanoscale Physics

Quantum critical behavior in chains of hindered dipolar planar rotors

Wenxue Zhang, Muhammad Shaeer Moeed, Estevao De Oliveira et al. (+2 more)

We study the ground-state properties of linear chains of dipolar planar rotors hindered by a six-fold on-site potential, a model motivated by water molecules confined in the hexagonal cavities of beryl. Using density matrix renormalization group (DMRG) calculations, we locate the quantum phase transition between the disordered and ferroelectrically ordered phases using the von Neumann entanglement entropy and the Binder ratio of the polarization. A sweep of the six-fold pinning strength shows that increasing hindrance shifts the critical dipolar coupling gc to smaller values. These results suggest that crystal-field hindrance can promote, rather than suppress, dipolar ordering. This work has implications for ferroelectricity and quantum-device tuning in confined molecular rotors
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All authors Wenxue Zhang, Muhammad Shaeer Moeed, Estevao De Oliveira, Hui Li, Pierre-Nicholas Roy

High Energy Physics (Theory) · Cross-listed from math.QA

Total Inner Products and Cyclic Chern-Simons Forms

Pavel Giterman and Jake P. Solomon

We introduce the notion of a total inner product on an $A_\infty$-algebra, and a cyclic Chern-Simons form associated to a topologically nilpotent element. The total inner product applied to the cyclic Chern-Simons form gives a superpotential function that is gauge invariant on solutions of the Maurer-Cartan equation known as bounding cochains. The derivative of the superpotential is computed. The definition of total inner product replaces strict symmetries that appear in previous notions of homotopy inner products with symmetries up to an infinite family of coherent homotopies. We show how to recover previous notions of homotopy inner products as special cases of total inner products. Total inner products are designed to facilitate the definition of descendent open Gromov-Witten invariants. The definitions of the total inner product and the cyclic Chern-Simons form use the total complex of cyclic codifferential forms, which gives a chain model for cyclic homology. We give explicit formulas for homotopy equivalences with other known models. We discuss also the notion of an $\infty$-trace, which arises from Connes' cyclic complex, and the associated $\infty$-modulus, which gives another gauge-invariant function on bounding cochains. In open Gromov-Witten theory, the $\infty$-modulus is used to normalize the bounding cochains to which the superpotential is applied. We develop our definitions for general curved Banach $A_\infty$-algebras, and give both unital and non-unital versions of the main results. In the unital setting, we work with weak bounding cochains, solutions of an inhomogeneous Maurer-Cartan equation involving the unit. Weak bounding cochains arise in the open Gromov-Witten theory of Lagrangian submanifolds with non-vanishing Maslov class. The derivative of the superpotential at a weak bounding cochain is related to the derivative of the $\infty$-modulus.
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Materials Science

Carrier Capture at Defects from Finite-Temperature Lattice Dynamics

Menglin Huang, Shanshan Wang and Shiyou Chen

Defect-assisted carrier capture is commonly described within nonradiative multiphonon (NMP) theory using normal modes of the equilibrium defect structure. This description becomes inadequate when finite-temperature lattice fluctuations explore configurations that cannot be represented by a fixed normal-mode basis. Here, we present a trajectory-based method for calculating carrier capture rate from first principles, which allows lattice relaxation and electron–lattice coupling matrix element to be reconstructed directly from correlation functions of finite-temperature lattice dynamics. For hole capture at C$_\mathrm{N}$ in GaN within harmonic regime, the method reproduces static NMP results including mode mixing and agrees with experiment. For oxygen vacancy in SiO$_2$, by contrast, the thermally sampled potential energy surface is substantially softer than the zero-temperature normal-mode harmonic expansion, strongly modifying the lattice relaxation and electron–lattice coupling, and producing pronounced changes in both the capture coefficient and its temperature dependence. These results establish the finite-temperature configurational ensemble, rather than phonon occupations alone, as an essential ingredient of defect-assisted carrier capture.
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Quantum Gases

Self-limiting electrostriction of a single ion in an ultracold polar gas: From mesoscopic ions to crystalline molecular rings

Ruiren Shi, Saajid Chowdhury, Leon Karpa et al. (+1 more)

We investigate the self-assembly of polar molecules around a single ion immersed in an ultracold, dilute two-dimensional molecular gas. The ion aligns and attracts the molecules through charge-dipole interactions, producing a strong electrostrictive accumulation around the impurity, while intermolecular repulsion limits further densification and favors spatially extended configurations. By combining global optimization with diffusion Monte Carlo, we calculate the evaporation energy as a function of the number of molecules bound to the ion. In contrast to conventional charged and van der Waals clusters, the evaporation energy exhibits a plateau-like dependence on cluster size, reflecting the sequential formation of concentric molecular rings. These structures are governed by the topology of the ion's electric field and by the competition between attractive ion-molecule interactions, repulsive intra-ring interactions, and attractive correlations between neighboring rings, rather than by conventional coordination or icosahedral packing. In the weak-interaction regime, the resulting structures form extended mesoscopic molecular ions, whereas stronger interactions produce increasingly rigid, crystal-like molecular rings. We further analyze their stability against thermal perturbations and the time-dependent ion trap and find that a broad range of clusters remain stable under experimentally relevant conditions. The intermolecular repulsion and dipolar geometry also suppress close-range ion-molecule encounters, suggesting an intrinsic shielding mechanism. Our results establish ion-bound polar-molecule clusters as a distinct class of mesoscopic molecular ions and open a route to studying charged impurities in quantum baths with anisotropic interactions.
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All authors Ruiren Shi, Saajid Chowdhury, Leon Karpa, Jesús Pérez-Ríos

Quantum Physics

Energetics in daemonic work extraction protocols via non-ideal QND-energy measurement

Daniele Morrone, Francesco Albarelli, Vittorio Giovannetti et al. (+2 more)

We address the problem of extracting work from a quantum system assisted by a quantum non-demolition (QND) energy measurement. When a perfect QND measurement can be performed and an auxiliary zero-temperature bath is available, the full energy of the quantum state can in principle be extracted even without any prior information on the input state. Owing to the presence of a zero-temperature bath, this is achieved at no energetic cost for the measurement process itself. On the contrary, here we consider what happens when the same protocol is implemented in non-ideal scenarios, specifically when the auxiliary bath has a finite temperature. In this case, not only is it impossible to extract the entire energy from the system, but the measurement strategy also acquires a non-zero energetic cost, accounting for both the interaction between system and measurement apparatus, and the corresponding Landauer erasure cost. We quantitatively assess the performance of these work-extraction protocols, both in absolute terms and through the so-called daemonic net gain, which explicitly includes the energetic cost of the measurement. We rigorously prove that, when access to a thermal bath is allowed in the extraction protocol, the daemonic net gain is always non-positive for any temperature of the auxiliary bath. Conversely, when only unitary operations are considered, the daemonic net gain can attain positive values. We further discuss these different figures of merit by analyzing a paradigmatic example for a single qubit system.
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All authors Daniele Morrone, Francesco Albarelli, Vittorio Giovannetti, Mauro Paternostro, Marco G. Genoni

Computational Physics · Cross-listed from stat.ML

Uncertainty propagation in auto-regressive random neural network models

Janice Adams and Daniele Venturi

We develop analytical and particle-based methods for uncertainty propagation in random neural network models, where both the inputs and network parameters are allowed to be random. Building on the piecewise-linear structure of the Leaky ReLU activation function, we derive a local approximation of the neural network output with respect to perturbations in both its inputs and parameters. This approximation is exact for perturbations that preserve the network activation pattern, and it allows us to compute analytical expressions for the probability density function and characteristic function of the network output, together with closed-form approximations for its mean and covariance. We extend this uncertainty propagation framework to autonomous dynamical systems whose one-step evolution map is represented by a random neural network. Repeated application of this map defines an autoregressive model, for which we derive recursive equations to propagate uncertainty in both the state and network parameters over time. These equations explicitly account for the state-parameter cross-covariance that develops under successive iterations of the network. Numerical experiments on the Lorenz-63 system and the Kuramoto-Sivashinsky equation demonstrate accurate uncertainty propagation through the predictability horizon and the applicability of the proposed framework to high-dimensional dynamical systems.
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High Energy Physics (Phenomenology)

Intensity-Frontier Signals of Warped Extra Dimensions

Doojin Kim, Deepak Sathyan and Ankur Verma

Can warped extra dimensions first appear at the intensity frontier rather than as TeV-scale resonances at colliders? We explore this possibility in extended warped models in which gravity propagates to a deep infrared region with warped scale $\Lambda_{\rm IR}\sim \mathcal{O}({\rm MeV})$, producing a densely spaced Kaluza-Klein (KK) graviton tower. We develop a benchmark photon-portal realization in which a visible vector sector reaches an intermediate GeV-scale brane, while the Higgs sector remains associated with a higher warped scale. The resulting graviton-photon couplings are controlled by wave-function overlap in the extra dimension, so the production rate is not governed simply by an independent mass and coupling as in conventional light-mediator simplified models. Instead, GeV-scale photons in beam-dump environments can preferentially produce heavier KK gravitons whose profiles probe the intermediate brane, after which the excited modes cascade down the tower. If decays into radion-like states are kinematically closed for the terminal mode, the lightest accessible KK graviton can be long-lived and decay visibly into a pair of photons. This leads to a distinctive intensity-frontier signature: heavy-mode production, intratower showering, and macroscopic electromagnetic decays. We present the model ingredients, derive the relevant overlap-controlled couplings, characterize the generic production and decay phenomenology, and discuss the theoretical and precision constraints on this class of low-scale warped scenarios.
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Quantum Physics · Cross-listed from math.CO

Perfect state transfer and Cayley presentations

Arnbjörg Soffía Árnadóttir and Krystal Guo

We study perfect state transfer on Cayley graphs from the point of view that state transfer is a property of a graph and not of a group. This paper is a bridge between the classical question about isomorphic Cayley graphs of non-isomorphic groups and quantum walks on graphs. We show that a Cayley graph of a group with an abelian subgroup of index two is a Cayley graph of an abelian group under any one of three hypotheses, two drawn from the theory of isomorphic Cayley graphs. A statement of the same kind holds for extraspecial groups: every Cayley graph of an extraspecial $p$-group of order $p^{2n+1}$ with a conjugacy-closed connection set is a Cayley graph of $Z_p^{2n+1}$. From these results we deduce that every explicit construction of perfect state transfer in the six papers we survey, on dihedral, dicyclic, generalized dihedral, $V_{8n}$ and extraspecial $2$-groups, is a non-abelian presentation of an abelian Cayley graph. Moreover, we show that a non-abelian group with an abelian subgroup of index two admits a connected Cayley graph with perfect state transfer if and only if its order is divisible by four. Genuinely non-abelian examples do exist. We prove that, for every odd prime power $q\ge 5$, the $SL(2,q)$ graph of Pantangi and Sin, which they showed to admit perfect state transfer, is a Cayley graph of no abelian group; to our knowledge, this is the first infinite family of Cayley graphs with perfect state transfer provably admitting no abelian Cayley presentation. We also construct an infinite family of Cayley graphs with peak state transfer and determine all regular subgroups of the automorphism group of every member. An appendix records a census of the connected vertex-transitive graphs with perfect state transfer on at most $30$ vertices.
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Quantum Physics

Collective Quantum Logic Spectroscopy

Raphael Kaubruegger, Matthew Patkowski, Yicheng Zhang et al. (+3 more)

Scaling trapped-ion quantum sensors from single ions to large ensembles is a key challenge for next-generation precision measurements. At the same time, many ion species of interest for optical clocks and tests of fundamental physics lack closed cycling transitions required for direct laser cooling and state detection. Collective quantum logic spectroscopy addresses both limitations by coupling an ensemble of sensor, or spectroscopy, ions to one or more logic ions that provide sympathetic cooling and state readout. Here, we establish the fundamental performance limits and operating regimes of this protocol, identifying how the interaction strength, interrogation time, and logic-ensemble size govern sensitivity, dynamic range, and robustness to experimental imperfections. We show that quantum-limited sensitivity can be retained even with a single logic ion, while increasing the number of logic ions substantially improves readout efficiency and robustness. Beyond precision metrology, the same collective interface enables many-body measurements relevant to quantum information processing, including parity measurements and stabilizer-like syndrome extraction. Our results establish collective quantum logic spectroscopy as a scalable framework for optical clocks, quantum-enhanced sensing, and trapped-ion quantum information processing.
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All authors Raphael Kaubruegger, Matthew Patkowski, Yicheng Zhang, Robert J. Lewis-Swan, David B. Hume, Ana Maria Rey

Earth and Planetary Astrophysics

Effects of Outer Giant Planets on In Situ Formation of Inner Super-Earths

Phoebe Sandhaus, Rebekah I. Dawson, Mariah G. MacDonald et al. (+2 more)

Recent studies have found an observational correlation between the presence of outer giant planets and inner super-Earths, which implies that outer giants do not suppress the formation of super-Earths. We simulate late-stage in situ planet formation in the presence of outer giant planets using $N$-body simulations. We investigate the effects of two sets of outer giants: the four Solar System giant planets and three dynamically active giant planets. Compared to systems without outer giants, we find that systems with the Solar System giants tend to form inner super-Earths that are more compact, coplanar, and circular, while the systems with the dynamically active giants form inner super-Earths that are more eccentric, inclined, and widely spaced, with lower intrinsic multiplicity. Including a contribution from systems that form with dynamically active giant planets allows us to match observable quantities of super-Earths, including their two component eccentricity distribution. However, matching the observed population requires different formation conditions prior to the giant impact stage for systems with vs. without giant planets. In our model, observed super-Earths that form in the presence of dynamically active outer giants emerge from disks with lower solid surface densities and without a depleted gas stage, suggesting that the giant planets may have reduced, but not prevented, delivery and/or accretion of solids in the inner disk. With a large enough sample of inner and outer systems, we could break down occurrence rates of inner super-Earths based on the properties of outer giants, and vice versa, and then compare these conditional probabilities with simulations.
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All authors Phoebe Sandhaus, Rebekah I. Dawson, Mariah G. MacDonald, Cody J. Shakespeare, Sarah Morrison

High Energy Astrophysical Phenomena

AT 2016blu: Accretion-Powered Outbursts in a Luminous Blue Variable and Compact Object Binary

Mojgan Aghakhanloo, Núria Torres-Albà, Nathan Smith et al. (+33 more)

We present the first X-ray detection of the supernova (SN) impostor AT 2016blu in NGC 4559. AT 2016blu exhibited 27 detected quasiperiodic (~113 day) outbursts between 2012 and June 2026, presumably triggered by periastron passages in an eccentric binary system in which the primary is a $\gtrsim 33~M_{\odot}$ luminous blue variable (LBV). AT 2016blu was serendipitously observed by Chandra in 2001-2002, prior to its first documented outburst in 2012, but the stacked archival data show no X-ray detection. We monitored the source's visual-wavelength variability around its predicted outburst time and triggered a Chandra Target of Opportunity program in March 2026, obtaining observations with detections over five closely spaced epochs. These data indicate an X-ray luminosity of $\log L_{\rm X} \approx 38.64 \pm 0.11$~erg~s$^{-1}$ and an accretion rate of $\dot{M} \gtrsim 8\times10^{-8}~M_{\odot}~\mathrm{yr^{-1}}$, consistent with the presence of a compact companion. We therefore conclude that AT 2016blu is the first known case of an LBV SN impostor whose outbursts are driven by intermittent accretion onto a compact object. Given that the system consists of a massive star and a compact companion, AT 2016blu is a high-mass X-ray binary, similar to SN 2010da, although the donor star in SN 2010da is a red supergiant.
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All authors Mojgan Aghakhanloo, Núria Torres-Albà, Nathan Smith, Raphael Baer-Way, Shazrene Mohamed, Alexei V. Filippenko, WeiKang Zheng, Thomas G. Brink, D. Andrew Howell, Brian Hsu, Moira Andrews, Joseph R. Farah, Curtis McCully, Kathryn Wynn, Réka Könyves-Tóth, Conor L. Ransome, Enrique Rathmann, Tamás Tordai, Sjoerd Dufoer, Charles Cynamon, Franz-Josef Hambsch, Thomas Rutherford, Simone Leonini, Franky Dubois, Ivo Peretto, Donald F. Collins, Lorenzo Betti, Lara Fossi, Irene Parenti, Vincenzo Pettina, Giulio Giordano Chiti, Maria Hofheinz, André Steenkamp, Sauro Gaudenzi, Nikola Antonov, Giuseppe Pappaa

High Energy Physics (Phenomenology)

Muon Capture on the Proton with Heavy-Light Currents

Evan Combes, Emanuele Mereghetti and Lucas Platter

We construct a non-relativistic Lagrangian that describes muon-proton electroweak interactions. We determine the leading order coefficients by matching onto the theory with non-relativistic nucleons and relativistic leptons. The most impactful $\mathcal{O}(\alpha)$ corrections to those coefficients are determined by matching the non-relativistic amplitudes for capture of a free muon on a proton to the corresponding relativistic one. We use our non-relativistic effective field theory framework to calculate the capture rate in muonic hydrogen, thereby including radiative corrections of order $\alpha$ and up to order $1/m_\mu$. Using results for the Fermi coupling previously derived in EFT, we obtain singlet and triplet capture rates of $\Gamma({}^1 S_0) = 724.07 \pm 5.45~\rm{s}^{-1}$ and $\Gamma({}^3 S_1) = 11.55 \pm 0.18~\rm{s}^{-1}$, respectively.
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High Energy Physics (Phenomenology)

First Search for Ultraheavy Dark Matter Using a Magnetically Levitated Particle

Dennis G. Uitenbroek, Dorian W. P. Amaral, Juehang Qin et al. (+4 more)

We present the first search for ultraheavy dark matter using a magnetically levitated particle. The POLONAISE experiment uses a milligram-scale ferromagnet levitated in a superconducting trap, admitting a force sensitivity of $0.07\,\mathrm{fN\,Hz^{-1/2}}$ and resolving impulses as small as $1\,\mathrm{TeV}/c$. Treating every candidate impulse as a possible dark matter event, we set optimum-interval upper limits on the neutron coupling $\alpha_n$ for dark matter interacting through a new light mediator. For dark matter masses $10^6\,\mathrm{GeV}/c^2\text{-}10^{15}\,\mathrm{GeV}/c^2$ and mediators lighter than $30\,\mathrm{meV}/c^2$, we exclude couplings as low as $\alpha_n = 3.2\times 10^{-9}$ at $95\%$ confidence level and set leading constraints on the dark matter-neutron cross section for composite dark matter. Our results extend levitated sensing beyond the mass reach of optical levitation by seven orders of magnitude into the ultraheavy dark matter frontier.
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All authors Dennis G. Uitenbroek, Dorian W. P. Amaral, Juehang Qin, Jurriaan Langendorff, Andrew Gingerich, Tjerk H. Oosterkamp, Christopher D. Tunnell