High Energy Physics (Experiment)
Exploring the limits of high-energy proton-pion separation in granular calorimeters
Andrea De Vita, Abhishek, Tommaso Dorigo et al. (+1 more)
Highly granular calorimeters provide detailed information about hadronic-shower development that may enable particle identification beyond their conventional role in energy measurement. We investigate how well this information can distinguish
protons from positively charged pions and how the achievable discrimination depends on detector
segmentation and particle energy. The study uses Geant4 simulations of isolated particles with energies from 10 to 100 GeV in a homogeneous lead-tungstate calorimeter. A Deep Sets model operating directly on
cell positions and detected energy and time outperforms a boosted decision tree based on reconstructed shower observables. With
cells measuring $3 \times 3 \times 6$ mm$^3$, Deep Sets achieves an accuracy of 93.8% at 10 GeV, decreasing to 67.2% at 100 GeV. Shower
topology is independently informative, deposited energy provides the largest additional contribution, and timing supplies complementary information. Coarser
segmentation reduces discrimination, with performance more sensitive to longitudinal than transverse granularity. These results provide an encouraging
benchmark for calorimeter-based
hadron identification and motivate its inclusion among the optimization targets for future highly granular calorimeters.
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All authors Andrea De Vita, Abhishek, Tommaso Dorigo, Pietro Vischia
Medical Physics
A Reference System for Open Source Portable Low-Field MRI
David Schote, Helge Herthum, Umberto Zanovello et al. (+8 more)
Despite its renewed
attention, the pathway to point-of-care portable low-field MRI systems remains challenging, limiting adoption across research groups. Incomplete documentation limits reproducibility, causing redesign and complicating cross-system comparison. Moreover, non-standardized testing and characterization complicates ethical approval for clinical studies. We present an open-source reference system for portable low-field MRI designed to support replication, reproducibility, benchmarking, and quantitative comparison. The system is fully open source, based on a ~50 mT permanent magnet, and integrated with a cloud-native acquisition platform. Pulseq-based calibration, characterization, and imaging sequences assessed noise level, eddy currents, image-based SNR, and
geometric accuracy. Quantitative T1, T2, and B0 mapping sequences were developed and evaluated against reference values. Initial results from independent replications at two sites were compared. The system reached a noise level of 1.4 relative to the thermal noise floor and short eddy-current decay constants of 27-32 us across all gradient channels.
Geometric deviations were below 2 mm over the field of view. Image-based SNR were consistent between the independent replications. Measured T1 values closely matched specified values, with an average absolute error of 3.1(1.8)%, while T2 values were overestimated by 10.4(5.8)%. Simulations showed only marginal errors for both quantities, suggesting experimental error sources for T2 mapping. The reference system combines openly documented hardware, software, calibration procedures, phantoms, quantitative MRI, and simulation tools in a reproducible ecosystem, aiming to support cross-site comparability, reproducible research, and collaborative development of future portable low-field MRI technologies.
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All authors David Schote, Helge Herthum, Umberto Zanovello, Julia Pfitzer, Ivo Jutte, Jan Gregor Frintz, Ilia Kulikov, Sebastian Littin, Frank Seifert, Christoph Kolbitsch, Lukas Winter
Chaotic Dynamics · Cross-listed from math.DS
Activated switching between coexisting limit cycles
Gabriel Margiani, Orjan Ameye, Oded Zilberberg et al. (+1 more)
Noise-activated switching between coexisting stable states is a fundamental mechanism underlying
stochastic dynamics in systems ranging from chemical reactions to neural networks. While this phenomenon is well understood for stationary attractors, it remains largely unexplored for limit cycles, whose periodic motion cannot be described by a static potential landscape. Here we experimentally demonstrate activated switching between two coexisting limit-cycle attractors in a driven nonlinear system of coupled resonators. Specifically, we introduce controlled fluctuations to directly observe the rare
stochastic transitions between two limit cycles and measure their dependence on noise intensity and driving strength. The measured switching rates are well described by a large-deviation theory, which replaces the conventional activation barrier by the action along the most probable transition path. Our results extend the concept of activated dynamics from stationary to limit-cycle attractors and establish a framework for modeling
stochastic transitions between limit cycles in driven-dissipative systems.
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All authors Gabriel Margiani, Orjan Ameye, Oded Zilberberg, Alexander Eichler
Quantum Physics
Distinct Modes of Quantum Information Transfer in Power-Law Long-Range Spin Networks
E.E. Marshall, C.C. Nelmes, T.J.G. Apollaro et al. (+2 more)
We identify different regimes of
quantum state transfer in long-range coupled
spin-$\frac{1}{2}$ systems, where naturally occurring power-law interactions enable rapid, high-fidelity transfer with minimal engineering. Across a broad range of interaction profiles, from effectively nearest-neighbour coupling to Coulomb interactions, we show how long-range connectivity fundamentally reshapes the mechanisms underlying information propagation within such systems. For effectively short-range interactions, transfer follows familiar ballistic transfer dynamics: an initially localised excitation spreads across many eigenmodes concentrated within the approximately linear region of the spectrum, enabling robust wavepacket motion. In contrast, increasing long-distance interactions via lowering the power-law exponent $\alpha$ ($\alpha=1-2$) drives a striking transformation, where the initial state becomes confined to progressively fewer eigenmodes, ultimately reducing the dynamics to the coherent participation of only a few states corresponding to the highest eigenenergies. This spectral localization gives rise to emergent long-range oscillations between distant sites, revealing a distinct – and faster – transfer mechanism arising from the intrinsic structure of long-range
quantum interactions rather than from full-system engineering pathways.
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All authors E.E. Marshall, C.C. Nelmes, T.J.G. Apollaro, T.P. Spiller, I. D'Amico
Materials Science
Anti-spin Laue groups: classification of anti-altermagnets and their representative minimal models
Colin Lange, Rodrigo Jaeschke-Ubiergo, Alexander Mook et al. (+1 more)
Anti-altermagnets exhibit odd-parity nonrelativistic
spin splitting, yet unlike even-parity altermagnets, their momentum-space
symmetries lack a reduced classification analogous to
spin Laue groups. Here, we introduce anti-
spin Laue groups, organized into three distinct classes, and identify 21 groups describing the odd-parity partial wave character of this unconventional class. Together with the 10
spin Laue groups of altermagnets, they complete the classification of nonrelativistic unconventional magnets with collinear momentum-space
spin polarization. Anti-
spin Laue groups also provide a many-to-one reduction of
spin space (point) groups by retaining only their action on the collinear momentum-space
spin polarization, thereby directly encoding the
symmetry-enforced nodal
spin-splitting character. Based on this we develop a systematic model-construction
algorithm yielding minimal, material-oriented four-band models. This framework places odd- and even-parity unconventional magnets on equal footing within a unified momentum-space
symmetry description.
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All authors Colin Lange, Rodrigo Jaeschke-Ubiergo, Alexander Mook, Jairo Sinova
Optics
Transversality Locks Longitudinal Gradients in Structured-Light Quadrupole Transitions
Kayn A. Forbes, Dale Green, Abdullah F. Alharbi et al. (+1 more)
Electric quadrupole absorption is driven by optical field gradients, not by field amplitudes alone. This distinction is crucial for structured light, where a paraxially small longitudinal field can generate a leading-order longitudinal gradient. For fully vectorial Laguerre-Gaussian modes, Maxwell transversality locks this longitudinal gradient to the transverse structured gradient of the leading paraxial field. This locking is therefore a general electromagnetic constraint, not a focusing-dependent correction that can be removed independently. Decomposing the symmetric-traceless optical field-gradient tensor into spherical components reveals a strongly channel-selective response: the $\Delta m=0$ transition requires the longitudinal gradient at the retained order, the $\Delta m=\pm1$ channels receive scalar and vectorial nonparaxial corrections on top of the carrier-scale longitudinal derivative of the transverse field, and the $\Delta m=\pm2$ channels remain transverse at the same order. These results show that longitudinal optical structure can enter structured-light quadrupole transitions as an indispensable leading-gradient contribution, even when the longitudinal field amplitude itself is paraxially small.
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All authors Kayn A. Forbes, Dale Green, Abdullah F. Alharbi, Akbar Salam
Materials Science
Ab initio-based Deep-Learning Prediction of Carrier Mobility in Strongly Anharmonic Materials
Juan Zhang, Boheng Zhao, Yang Li et al. (+4 more)
Predicting charge transport in strongly anharmonic materials, particularly ultralow thermal conductors, remains a major challenge for first-principles methods. In such systems, perturbative treatments of electron-
phonon interactions and the harmonic
phonon picture often break down, necessitating non-perturbative approaches. The ab initio Kubo-Greenwood(aiKG) formalism provides a rigorous framework for evaluating temperature-dependent carrier transport beyond the harmonic approximation. Nevertheless, its practical application is computationally demanding because it requires large supercells, extensive statistical sampling, and extrapolation to the zero-frequency limit. In this work, we introduce an artificial-intelligence(AI)-assisted aiKG framework that incorporates the deep-learning
Hamiltonian model. By predicting the Kohn-Sham
Hamiltonian with sub-meV accuracy for supercells of up to 250 atoms, the model bypasses the costly iterative self-consistent field calculations while retaining first-principles reliability within the scope of effects captured by the training data. Using a strongly anharmonic thermal
insulator, potassium iodide(KI) as a
benchmark system, we demonstrate that the proposed approach enables efficient simulations of electronic structure and transport properties from a large supercell. The framework reproduces temperature-dependent carrier mobilities, spectral functions, and effective masses in close agreement with the underlying density functional theory while reducing computational cost to 10%. These results suggest that the AI-assisted aiKG framework can make non-perturbative transport calculations tractable for strongly anharmonic materials, opening a scalable route towards realistic simulations and accelerated discovery of new functional materials.
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All authors Juan Zhang, Boheng Zhao, Yang Li, Yong Xu, Hao Zhang, Kisung Kang, Matthias Scheffler
Instrumentation and Detectors
The Radioactive Background of the JUNO Calibration System
Rui Li, Youhui Yun, Zhangming Chen et al. (+13 more)
The Jiangmen Underground
Neutrino Observatory (JUNO) experiment is a reactor antineutrino detector employing 20 kton of ultra-pure
liquid scintillator to determine the
neutrino mass ordering and to precisely measure oscillation parameters. The total singles background rate from radioactivity is required to be below 10 Hz in the energy range of 0.7-12 MeV within the fiducial volume for reactor
neutrino analysis. The calibration system is designed to characterize the detector energy and position responses, while several of its components are located close to the target and may contribute to the background budget. Therefore, extensive material screening and selection are required to construct a low-background calibration system and to ensure that its contribution remains within the design requirements. In this work, a comprehensive study of the radioactive background induced by the calibration system is presented, including material radioactivity measurements using high-purity germanium detectors and
neutron activation analysis techniques, detailed Monte Carlo simulations to evaluate the background, and comparisons with in-situ detector data to validate the predictions. In this data analysis, dedicated spatial selection methods are developed to isolate calibration-related contributions and to suppress the
liquid scintillator background. The total radioactivity contribution from the calibration system is estimated to be less than 76 mHz, which satisfies the requirement of 200 mHz (2% of the total background budget). The results from in-situ data are found to be consistent with the expectations based on material assay and simulation within uncertainties. These results demonstrate that the calibration-induced background is well understood, in agreement between data and simulation, and negligible for reactor antineutrino measurements in JUNO.
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All authors Rui Li, Youhui Yun, Zhangming Chen, Junting Huang, Jiaqi Hui, Haojing Lai, Jianglai Liu, Yankai Liu, Yue Meng, Akira Takenaka, Ziqian Xiang, Feiyang Zhang, Ping Zhang, Qingmin Zhang, Tao Zhang, Yuanyuan Zhang
Superconductivity
Emergent BEC mechanism in flat-band superconductors
V. Berger, I.S. Tupitsyn, B. Currie et al. (+3 more)
The formation of bound bosonic pairs of
fermions, followed by their Bose-Einstein (quasi) condensation (BEC), is a foundational mechanism of superconductivity. At low filling, flat-band superconductivity is well captured by this mechanism provided the flat band is separated from the occupied lower band by an energy gap. However, particularly high $T_c$ values are anticipated when the non-interacting flat and lower bands touch—as in the prototypical attractive Lieb-
lattice model studied here—invalidating the conventional picture: while interactions might protect the bound state by opening a gap, no small parameter guarantees the separation of the bound-state energy from this gap or occupied-band excitations, leaving the pair's fate uncertain. Based on a controlled-precision numerical protocol—which we demonstrate to be essential in this fundamentally non-perturbative problem—we show that the BEC mechanism, underpinned by an interaction-induced gap, is generically robust and remarkably efficient:
fermions doped into the flat band form bound pairs within this gap with an anomalously light effective mass, enabling an exceptionally high $T_c$.
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All authors V. Berger, I.S. Tupitsyn, B. Currie, B.V. Svistunov, E. Kozik, N.V. Prokof'ev
Quantum Physics
Bernstein-Vazirani Networks: Quantum Machine Learning by Interference
Natacha Kuete Meli, Tolga Birdal, Prayag Tiwari et al. (+2 more)
We introduce Bernstein-Vazirani Networks (BVNs), a non-variational
quantum machine learning framework that leverages
quantum interference for supervised learning, demonstrated on
vision and representation learning tasks. In their standard form, BVNs follow the principle of
quantum Fourier sampling: labelled data are placed in superposition and interfered in the
Fourier basis to extract globally informative features. We then define generalised BVNs that enable interference in problem-adapted bases, yielding more expressive models under the same measurement budget as in the standard setting. BVNs achieve universal function approximation through (over)complete interference bases, while training of BVNs is gradient-free. Experiments on synthetic and real-world classification tasks, as well as implicit image representation, show strong generalisation capabilities and competitive performance with classical and
quantum baselines.
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All authors Natacha Kuete Meli, Tolga Birdal, Prayag Tiwari, Vladislav Golyanik, Michael Moeller
Chemical Physics
Universal Machine-learning Molecular Dynamics at the Speed of Empirical Potentials
Tiancheng Li, Jianming Xue, Linfeng Zhang et al. (+2 more)
No interatomic potential has offered universality across chemistry, near-first-principles accuracy and the speed of empirical potentials at once. Here we introduce DPA4C, an equivariant potential whose architecture and compressed CUDA operators are co-designed under deployment constraints to pursue accuracy and efficiency together. Five variants spanning a 49-fold parameter range form the high-throughput end of the measured accuracy–throughput frontier. The largest variant approaches the accuracy of the MACE-Omat models at about two orders of magnitude higher measured throughput. The most compact reduces the energy, force and stress errors of the fastest existing universal MLIP by 61.4%, 48.1% and 34.3% at 1.92 times its saturated throughput. All five variants complete multimillion-atom simulations on a single GPU and run molecular dynamics for 2.048 billion atoms on 1,024 16-GB NVIDIA V100 GPUs at 83.3–91.2% weak-scaling efficiency. Compared with the MEAM empirical potential, DPA4C-Nano reaches 1.8 and 2.5 times the saturated throughput in single-GPU scans on the same V100 hardware for diamond carbon and FCC copper, respectively. DPA4C therefore brings
quantum-trained universal accuracy into a regime of speed and system size previously associated with empirical potentials.
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All authors Tiancheng Li, Jianming Xue, Linfeng Zhang, Duo Zhang, Han Wang
Cosmology and Nongalactic Astrophysics
Dipolar power asymmetry in wide-angle correlations of galaxy density, velocity and ellipticity
Yusuke Mikura, Teppei Okumura, Ippei Obata et al. (+1 more)
The large-scale structure of the universe has the potential to probe anomalies suggested by observations of the
cosmic microwave background. In this work, we focus on a position-dependent dipolar modulation of the
primordial power spectrum and develop a full-sky formalism for computing correlation functions of
galaxy density, velocity and ellipticity. By comparing the correlation functions obtained with and without the plane-parallel approximation, we show that wide-angle corrections become non-negligible for opening angles $\Theta \gtrsim 30^\circ$. Our results demonstrate that wide-angle corrections must be taken into account when testing the dipolar modulation with future large-scale structure surveys.
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All authors Yusuke Mikura, Teppei Okumura, Ippei Obata, Maresuke Shiraishi
Solar and Stellar Astrophysics
The Ultrafast Line-Driven Wind from the Double-Degenerate Merger Remnant WD J005311
Kazuma Kato and Kazumi Kashiyama
We systematically construct steady-state wind solutions for double-degenerate merger remnants consisting of a degenerate oxygen-neon core and an optically thick expanding envelope powered by carbon-shell burning, with winds accelerated by radiation pressure including line driving. For a given envelope composition, each solution is characterized by two
eigenvalues: the degenerate core mass, $M_{\rm WD}$, and the total envelope and wind mass, $\Delta M$. We find that wind solutions exist for $M_{\rm WD} \gtrsim 1.0\,M_\odot$. For a given $M_{\rm WD}$, the solutions transition with decreasing $\Delta M$ from slow, continuum-driven winds to ultrafast, line-driven winds, forming a sequence that can be interpreted as the temporal
evolution of a merger remnant. We apply these solutions to WD J005311, a
Galactic double-degenerate merger-remnant candidate with an ultrafast wind of $v_{\rm w} \sim 0.05\,c$. Its luminosity, effective temperature, and mass-loss rate are consistently reproduced with $M_{\rm WD} \sim 1.15-1.25\,M_\odot$ and $\Delta M \sim (1.8-5.7)\times 10^{-3}\,M_\odot$. Combining our evolutionary analysis with observations of the surrounding nebula Pa 30 and historical records of SN 1181, we argue that WD J005311 began launching a continuum-driven wind $400-650$ yr after the putative merger and transitioned to the ultrafast-wind phase approximately $100$ yr ago. This phase is expected to continue for another $\sim 1000$ yr, during which the WD will remain below the Chandrasekhar mass and avoid collapse into a
neutron star. Before the continuum-driven wind phase, the remnant may have passed through a more bloated, hydrostatic
giant phase with a slower but more massive wind. Future observations of the wind nebula could test this scenario by revealing signatures of interactions between the slow, massive wind and the ultrafast wind.
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Chemical Physics
Molecular Implementation of the Machine-Learned Skala Exchange-Correlation Functional in CP2K through GauXC
Franz Pöschel, Johann Pototschnig, Frederick Stein et al. (+6 more)
Machine-learned exchange–correlation (XC) functionals offer a route to improve Kohn–Sham density-functional theory without incurring the cost of explicitly correlated electronic-structure methods. Their use in production simulation codes, however, requires a well-defined mapping between the learned model and the host-code density representation. We formulate and implement a Skala-1.1 interface in CP2K through the external GauXC library. CP2K supplies the geometry, Gaussian basis,
spin-resolved atomic-orbital density
matrix, and communicator, while GauXC evaluates the XC energy, atomic-orbital potential
matrix, and available
nuclear derivatives. The interface accepts both all-electron and valence-only density
matrices. The latter may arise from separable dual-space pseudopotentials or molecular effective-core potentials. Implementation errors are isolated from functional differences by comparing the Perdew–Burke–Ernzerhof (PBE) functional evaluated through GauXC with native CP2K PBE. The resulting interface gives consistent energies, forces validated against finite-difference total-energy checks, and force-based molecular-virial diagnostics for representative molecular cases. The dietGMTKN55
benchmark suite is evaluated with an all-electron Gaussian augmented plane-wave treatment for elements up to bromine and def2 effective-core potentials for the heavier elements. The resulting aggregate mean absolute deviation of 1.255 kcal/mol is within 0.012 kcal/mol of the corresponding Skala reference value of 1.243 kcal/mol. This work establishes a validated molecular implementation of Skala in CP2K through GauXC.
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All authors Franz Pöschel, Johann Pototschnig, Frederick Stein, Andreas Knüpfer, Thijs Vogels, Stefano Battaglia, Sebastian Ehlert, Jürg Hutter, Thomas D. Kühne
Materials Science
The role of weak interfaces in the tensile deformation and fracture of particle-filled polymers studied by phase-field model
Xu Chen, Ya Duan, Xiaoying Zhuang et al. (+1 more)
Weak particle-
matrix interfaces play a critical role in the tensile fracture of particle-filled
polymer composites, but how they govern progressive debonding, fracture localization, and the resulting changes in macroscopic mechanical properties remains insufficiently understood. In this study, a cohesive-zone phase-field model incorporating a hyperelastic
polymer matrix and a smeared interface is employed to investigate the coupled
evolution of interfacial debonding and
matrix fracture in particle-filled
polymer composites. The model is calibrated against and compared with uniaxial tensile responses of particle-filled polyurethane composites and then used to study how interfacial strength, interfacial fracture energy, and
matrix fracture properties affect the macroscopic stress-strain response and damage
evolution. The results show that weak interfaces can induce an intermediate softening regime in the stress-strain response, characterized by a reduced effective tangent stiffness and associated with distributed interfacial damage. Interfacial strength mainly controls the initiation of debonding, whereas interfacial fracture energy affects whether debonding can develop progressively in a distributed manner or rapidly localizes into a dominant crack band. Comparisons with well-bonded reference systems further demonstrate that weak interfaces may reduce the maximum stress but increase the strain at break by promoting distributed debonding around particles and delaying the formation of a dominant crack band. These findings clarify the dual role of weak interfaces and provide a mechanistic understanding of interface-controlled tensile failure in particle-filled
polymer composites.
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All authors Xu Chen, Ya Duan, Xiaoying Zhuang, Timon Rabczuk
Earth and Planetary Astrophysics
A Search for helium in the atmospheres of three sub-Neptunes and a super-Earth around M-dwarfs
Kiyoe Kawauchi, Norio Narita, Yuichi Ito et al. (+26 more)
Thousands of sub-Neptunes have been discovered mainly through space-based surveys such as Kepler and TESS. Their bulk compositions and internal structures are thought to reflect their formation and evolutionary pathways, and atmospheric observations provide constraints on these processes. The near-infrared helium triplet is a potential tracer of extended, escaping H/He atmospheres. Recent models that include
geometric effects suggest that
planets orbiting nearby late M
dwarfs may offer favorable conditions for detecting this signal. Nevertheless, helium has been reported for only three
planets around M
dwarfs to date. We conducted high-resolution transmission spectroscopy of three sub-Neptunes (TOI-2136b, TOI-654b, and LP 791-18c) and a super-Earth (TOI-1634b) orbiting M
dwarfs with the InfraRed Doppler (IRD) spectrograph on the Subaru
Telescope. We find no statistically significant helium absorption in any target; accordingly, we derive 95% confidence upper limits on the helium line depth of 1.36%, 0.60%, 2.07%, and 3.00%, and on the equivalent width of 7.3, 2.1, 7.4, and 9.1 mÅ, for TOI-2136b, TOI-1634b, TOI-654b, and LP 791-18c, respectively. We further explored constraints on the upper-atmospheric temperature and mass-loss rate by comparing these results with isothermal Parker-wind models. While we have compared with self-consistent ATES models of
primordial H/He atmospheres spanning a range of assumed X-ray luminosities, changes in the assumed XUV flux do not appear to account for the non-detections. The results suggest that these
planets have metal-enriched H/He primary atmospheres or non-
primordial atmospheres, such as water-rich envelopes. Future observations of other absorption lines, such as Lyman-$\alpha$, H-$\alpha$, and H$_2$O, may provide further constraints on these atmospheres.
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All authors Kiyoe Kawauchi, Norio Narita, Yuichi Ito, Akifumi Nakayama, Teruyuki Hirano, Masayuki Kuzuhara, Mayuko Mori, Izuru Fukuda, Akihiko Fukui, Yuya Hayashi, Yasunori Hori, Masahiro Ikoma, Kai Ikuta, Taiki Kagetani, Yugo Kawai, Tadahiro Kimura, Vigneshwaran Krishnamurthy, Huan-Yu Teng, Noriharu Watanabe, Yujie Zou, Hiroki Harakawa, Klaus Hodapp, Tomoyuki Kudo, Takashi Kurokawa, Jun Nishikawa, Masashi Omiya, Motohide Tamura, Akitoshi Ueda, Sébastien Vievard
Strongly Correlated Electrons
Sign-problem-resilient singular-value probe in determinant quantum Monte Carlo
Wen Chen and Rubem Mondaini
The sign problem limits determinant
quantum Monte Carlo studies of strongly correlated
fermion systems. In the
spin-channel Hubbard-Stratonovich decoupling,
spin correlations are exactly related to auxiliary-field correlations. This relation implies that an
antiferromagnetic transition reorganizes auxiliary-field configurations and thereby changes the statistical structure of the resulting
fermion matrices. We use the adjacent gap ratio of low-lying singular values of the space-time
fermion matrix to probe interaction-driven transitions in two half-filled honeycomb-
lattice Hubbard models. In the sign-free honeycomb Hubbard model, the statistic tracks the established transition from a Dirac semimetal to an
antiferromagnetic Mott
insulator. In the complex-weight Haldane-Hubbard model, the transition-sensitive feature remains visible in the phase-quenched reference ensemble and occurs near previous estimates of the transition. Moreover, phase reweighting only weakly modifies the gap ratio over the regimes investigated, despite the rapid suppression of the average phase. These results establish singular-value statistics as a sign-problem-resilient probe of interaction-driven transitions in determinant
quantum Monte Carlo.
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Quantum Physics
Interface Capacity and Architectural Replenishment Determine Entanglement-Generation Speed in Quantum Networks
Shi-Ju Ran
We show that
entanglement-generation speed across a fixed network interface is governed by two distinct resources: the entangling capacity of the interface itself and the ability of the surrounding architecture to replenish it with fresh degrees of freedom. For fermionic Gaussian dynamics, we derive the coefficient-sharp bound $\sum_k|\dot\theta_k|\leq\frac12\|K_{AB}\|_*$ on the collective speed of the canonical
entanglement angles. Explicit Ising-chain rematching trajectories saturate this bound, thereby certifying exact minimum interaction times under the stated control model. Beyond the Gaussian setting, exhaustive optimization of the complete $N=8$ tree–tree family shows that, at fixed interface capacity, first-layer
entanglement, connectedness, and edge budget, the saturation depth is exactly classified by rooted architecture. With higher-resolution $x$-only control, variational
entanglement-enhancing-field (VEEF) optimization reaches the numerically resolved fast-$X$ optimum in a two-channel
benchmark. Across all 21
symmetry-reduced rooted orbits, a pre-specified two-time VEEF growth diagnostic recovers the complete replenishment partition directly from optimized dynamics. Interface capacity therefore sets how much entangling flux is available, whereas architecture determines whether fresh degrees of freedom can continually replenish the interface and sustain repeated use of that capacity.
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High Energy Astrophysical Phenomena
Quantifying uncertainty in the neutron-star equation of state using point estimates and posterior distributions
André Gonçalves da Silva and Ricardo Luciano Sonego Farias
We investigate uncertainty quantification for the
neutron-
star equation of state (EOS) by comparing point-estimation and distributional inference approaches using the same Chebyshev and piecewise-linear parameterizations. We combine
neutron-
star mass–radius and gravitational-wave
tidal-deformability information within
Bayesian, multilayer-perceptron (MLP), and normalizing-flow frameworks. Although the methods yield similar mean EOS behavior, the deterministic MLP produces substantially narrower uncertainty bands at high densities. We show that this behavior is associated with the point-estimation objective, which maps degenerate solutions toward the conditional mean rather than representing the full parameter posterior. By contrast, the normalizing flow yields distributions more consistent with the
Bayesian inference. Our results demonstrate that reliable uncertainty quantification of the high-density EOS requires methods that represent conditional probability distributions rather than only point estimates.
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Optics
Influence of metal nanoparticles on whispering gallery modes of a microcavity
Tulika Agrawal, Venkata Dantham, Shubhayan Bhattacharya et al. (+3 more)
Photonic microcavities offer high energy density and low mode volume and attract special
attention due to wide range of applications. Subsequent developments in the area of plasmonic nanocavities have also opened up applications despite their high absorptive properties. In the last two decades, photonic-plasmonic hybrid microcavities have been investigated extensively. In this article, we have conducted a review of the literature on photonic and plasmonic systems individually as well as in hybrid systems. Along with the underlying physics, applications such as cavity
quantum electrodynamics, lasing, sensing, nonlinear optics and Raman spectroscopy have been reviewed. The outputs of the systems for each applications have been discussed and compared for photonic and hybrid systems. This review will provide a thorough understanding of the effects of optical cavities and plasmonics and their applications.
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All authors Tulika Agrawal, Venkata Dantham, Shubhayan Bhattacharya, Aneesh Veluthandath, Stephen Arnold, Prem Bisht
Optics
3D trapping of a meta-atom in an intensity minimum
Bin Lu, Adeel Afridi, Nadine Meyer et al. (+1 more)
High-refractive-index particles have recently attracted a growing interest in optical levitation experiments, offering the ability to further engineer optical forces through electromagnetic Mie resonances. Unlike standard silica particles, which are predominantly trapped in the dipole regime and exhibit trap frequencies mainly determined by material density, resonant meta-atoms formed by high-index particles enable qualitatively new trapping behaviors. In this work, we experimentally investigate the trapping of resonant silicon particles in an optical standing wave. A direct comparison of silicon and silica highlights the fundamental differences in their optical force scaling and trapping dynamics. Beyond conventional trapping at intensity-maxima, we demonstrate deterministic and stable three-dimensional trapping of silicon nanoparticles in optical intensity minima, a regime that remains inaccessible for silica particles. Drawing a mesoscopic analogy with blue-detuned atom trapping, our results establish meta-atoms as a versatile approach to further extend the optical manipulation tool box towards accessing novel trapping regimes e.g. in close proximity to a surface.
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All authors Bin Lu, Adeel Afridi, Nadine Meyer, Romain Quidant
Atmospheric and Oceanic Physics
Extremes on Rewind: Generating 1,000-Member Ensembles Initialized at a Final Condition
Jerry Lin, Mu-Ting Chien, Mansi Sakarvadia et al. (+1 more)
Scenario planning for rare, high-impact events often requires massive ensembles to stochastically sample relevant trajectories. Although autoregressive weather emulators can efficiently generate such ensembles, isolating trajectories of interest requires sifting through petabytes of data, a challenge that grows exponentially with lead time and rarity. In contrast, a non-autoregressive foundation model like
Climate in a Bottle
video (cBottle-
video) can directly sample trajectories terminating in extremes, avoiding large-ensemble search. We use cBottle-
video to generate 1000-member ensembles with start- and/or end-conditioning across three extreme events—the 2021 Pacific Northwest (PNW) heatwave, Superstorm Sandy, and Hurricane Ian. Antecedent 500 hPa geopotential height ($z_{500}$) spread at the free end of end-conditioned ensembles reaches 84–89% of the final-state spread of start-conditioned ensembles, revealing substantial diversity consistent with each extreme event. For the 2021 PNW heatwave, end-conditioned ensemble members begin uniformly warmer than reanalysis and stay warm, replacing the observed rapid intensification with persistent antecedent heat. For Superstorm Sandy, the leading modes of $z_{500}$ at the antecedent end of the end-conditioned ensemble explain 44% of the variance in track latitude, and roughly 10% of ensemble members begin as stronger hurricanes than Sandy. For Hurricane Ian, variation in the first landfall location among end-conditioned trajectories underscores the importance of accounting for intermediate hazard exposure in risk planning.
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All authors Jerry Lin, Mu-Ting Chien, Mansi Sakarvadia, Elizabeth A. Barnes
Astrophysics of Galaxies
The progenitors of $z\gtrsim10$ JWST galaxies in the COLIBRE simulations
Evgenii Chaikin, Andrew Pontzen, Carlos S. Frenk et al. (+4 more)
JWST has revealed a large population of luminous
galaxies ($M_{\rm UV}\lesssim -20$) at
redshifts $z \gtrsim 10$, widely interpreted as posing a challenge to models of
galaxy formation within the $\Lambda$CDM cosmology. Here, we search for counterparts of the JWST
galaxies in the COLIBRE simulations of
galaxy formation. Although these simulations have not been tuned to reproduce any $z > 0$ observations, we find a population of COLIBRE
galaxies with properties similar to those of the JWST
galaxies, and trace them to their earliest evolutionary phases, $z\simeq25$, to investigate the onset of
galaxy formation. We study the
evolution of
galaxy stellar masses, sizes,
star formation rates, UV magnitudes,
metallicities, central black hole masses, and molecular gas and
dust content, finding good agreement with observationally inferred properties at $z > 10$, except for UV magnitudes and
dust masses, which COLIBRE underpredicts and overpredicts, respectively. Our results indicate that the standard
galaxy formation physics and $\Lambda$CDM cosmology adopted in COLIBRE are sufficient to reproduce a broad range of properties of the most extreme $z > 10$ JWST
galaxies - including their compact sizes,
stellar masses, gas content, and
metallicities. We show that the discrepancies with the UV magnitudes and
dust masses can both be attributed to the uncertain rate of grain growth at high
redshift, possibly alongside a top-heavy
stellar initial mass function. These findings provide strong evidence that the standard cosmological model can naturally explain even the most extreme
galaxies in the early Universe.
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All authors Evgenii Chaikin, Andrew Pontzen, Carlos S. Frenk, Joop Schaye, Shengdong Lu, Robert A. Crain, Anna Durrant
Instrumentation and Methods for Astrophysics
Physical Optics Analysis of Polarization Effects in SO LAT Reflectors
Xiaodong Ren, Patricio A. Gallardo and Jon E. Gudmundsson
We present a physical-optics analysis of the polarization response of the reflective optical of the Simons Observatory Large Aperture
Telescope (SO LAT). Far-field co-polar and cross-polar beam patterns are simulated for representative feedhorn positions, and the corresponding polarization-angle offsets are evaluated. The results show that the crossed-Dragone reflector system has good polarization performance. Off-axis feed positions introduce small, position-dependent offsets in the far-field polarization orientation, with a maximum value of 0.23 degrees, due to optical asymmetry. The relative polarization-angle offset under feedhorn polarization rotation, however, remains consistent with zero. No significant frequency dependence is found over the frequencies considered. These results provide a practical reference for polarization-angle calibration and for assessing reflector-induced polarization systematics in the SO LAT.
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Nuclear Theory
Symmetries of QCD and their relevance for low-energy nuclear physics
Matthias R. Schindler
QCD, the theory of the strong interactions, is formulated in terms of
quarks and
gluons, while low-energy
nuclear physics deals with
hadrons such as
protons,
neutrons, and pions.
Symmetries establish a systematic connection between these two descriptions of strongly-interacting systems. The objective of this article is to review the
symmetries of QCD and to explain how they constrain hadronic interactions.
Chiral symmetry, which emerges in QCD in the limit of massless
quarks, is of particular importance for low-energy
nuclear physics. Together with its explicit and spontaneous breaking,
chiral symmetry provides the basis for
chiral perturbation theory, the effective field theory describing pions and nucleons at low energies.
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Quantum Physics
RushHour: A Dynamically Reconfigurable Lattice-Surgery Architecture
Nathaniel Tornow, Aleksandra Świerkowska, Peter Wegmann et al. (+1 more)
Practical fault-tolerant
quantum computing (FTQC) requires efficient
lattice surgery (LS), so that large
algorithms fit on resource-constrained
quantum chips. Existing approaches, however, are rigid:
qubits, routing space, and resource states are allocated ahead of execution, which prevents running on small chips, leaves statically scheduled executions with large time overheads, and fixes each design at a single area of the space-time trade-off. We present dynamic LS, which enables efficient reconfiguration of the ancilla space, just-in-time allocation of resource states, and dynamic rotations of logical
qubits, thereby spanning the entire space-time trade-off with a single, unified approach. We realize dynamic LS with RushHour through a hardware-compiler co-design: the RushHour ISA formalizes and programs our dynamic
lattice model, the
Lattice Management Unit abstracts dynamic
lattice management and performs efficient
lattice reconfiguration, and the RushHour Compiler compiles logical
circuits for physical chips into optimized ISA programs while pipelining instructions. We evaluate RushHour against six state-of-the-art compilers and two resource models. On the smallest chips, 86% of
benchmarks run only with RushHour, while existing approaches require 1.2-3.5$\times$ larger chips. On space-constrained early-FTQC chips, RushHour runs a median 2.3-7.2$\times$ faster than the best feasible alternative, while achieving results comparable to the state of the art on very large chips. RushHour's constructive results run 4.8$\times$ from an idealized-machine resource limit.
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All authors Nathaniel Tornow, Aleksandra Świerkowska, Peter Wegmann, Pramod Bhatotia
General Relativity and Quantum Cosmology
Duru-Kleinert Path Integral in Unimodular Quantum Cosmology
Xiao-Kan Guo
The Wheeler-DeWitt equation of a flat Friedmann-Lemaitre-Robertson-Walker universe filled with pressureless
dust and a cosmological constant in unimodular
gravity reduces, for a specific factor ordering and a specific self-adjoint extension, to the $l=0$ radial Schrödinger equation of a hydrogen atom. We revisit this correspondence from the point of view of the Green's functions and the Duru-Kleinert path integrals. Working directly with the reduced operator on the half-line, we obtain the Green's function in Whittaker form and fix its normalization by a Wronskian argument. Its Gamma-function poles give the reduced-operator spectrum which recovers the quantization of the negative cosmological term. We also perform the operator-level Duru-Kleinert transformation, whose Jacobian generates a barrier which after rescaling is exactly the centrifugal barrier of a two-dimensional oscillator. Retaining it reproduces the Coulomb pole condition. For positive cosmological constant, we give the continuum spectral measure and the Sommerfeld factor.
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Solar and Stellar Astrophysics
Quadrupole White-light Sources in an X1.2 Flare Observed by ASO-S/LST/WST and SDO/HMI
Zhichen Jing, Ying Li, Dechao Song et al. (+2 more)
We present observations of an X1.2 white-light
flare on 2023 January 6, which exhibits a rare quadrupolar white-light source configuration. This event was observed by the White-light
Solar Telescope (WST; 3600 Å) aboard the Advanced Space-based
Solar Observatory and the Helioseismic and
Magnetic Imager (HMI; 6173 Å) aboard the
Solar Dynamics Observatory. Four
flare-related footpoints (labeled as FP1–FP4) were nearly simultaneously identified in both WST 3600 Å\ and HMI 6173 Å\ continua, associated with a quadrupolar
magnetic configuration and a failed filament eruption. The inner sources of FP1 and FP2 showed a similar enhancement of $\sim$65%/10% in the WST/HMI continuum, while the outer sources of FP3 and FP4 exhibited weaker responses. The inner footpoints had earlier responses in UV and EUV bands and were spatially coincident with the hard X-ray (HXR) footpoint sources. The two southern footpoints (FP2 and FP4) showed stronger HXR and white-light emissions than their northern counterparts (FP1 and FP3), with FP4 uniquely exhibiting a distinct HXR emission above 60 keV, in contrast to the absence of such an emission at FP3. Notably, faint WST 3600 Å\ enhancements at FP4 were observed during the gradual phase, temporally consistent with the fallback of filament material. This X1.2
flare presents a novel quadrupolar white-light structure, enriching our understanding of the generation and
evolution of white-light
flares.
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All authors Zhichen Jing, Ying Li, Dechao Song, Qiao Li, Zhengyuan Tian
Quantum Physics
Deviation from linear reduced dynamics always occurs for each non-factorisable system-environment unitary evolution
Iman Sargolzahi
In the simplest approximation, the reduced dynamics of a
quantum system $S$ interacting with its environment $E$ is considered to be given by a completely positive map. But, in general, this is not the case. In fact, the reduced dynamics of the system in not even linear, in general. Whether the reduced dynamics is linear or not is determined by two factors: the set of possible initial states of the system-environment $\mathcal{S}=\left\lbrace \rho_{SE} \right\rbrace $, and the joint system-environment
unitary evolution $U$. When $U$ is factorisable as $U=U_S\otimes U_E$, then we can choose $\mathcal{S}=\mathcal{D}$, where $\mathcal{D}$ is the set of all system-environment density operators. In other words, when $U$ is factorisable, the reduced dynamics of the system $S$ is linear (in fact
unitary) for arbitrary initial state of the system-environment $\rho_{SE}$. We show that this result cannot be generalized to any non-factorisable $U$: For any non-factorisable
unitary evolution of the whole system-environment $U$, the set $\mathcal{S}$ must be chosen as a proper subset of $\mathcal{D}$ to achieve linear reduced dynamics. As a byproduct, considering a convex set of possible initial states of the system-environment $\mathcal{S}$ such that $\mathrm{Tr}_{E} \ \mathcal{S}=\mathrm{Tr}_{E} \ \mathcal{D}$, we show that when the reduced dynamics of the system, for one system-environment
unitary evolution $U_1$, is positive, but not completely positive, this implies that reduced dynamics is not linear for another $U_2$.
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Nuclear Theory
Balancing theory uncertainties in ab initio nuclear structure calculations: Many-body truncation versus finite basis size
L. Zurek, U. Vernik, P. Demol et al. (+3 more)
First-principles calculations of atomic
nuclei are necessarily incomplete as the Schrödinger equation is solved using approximate methods and due to the finite dimension of the employed
Hilbert space. By balancing many-body truncation and basis-size uncertainties, we formalize a criterion for the optimal one-body basis dimension in a given ab initio
nuclear structure computation. Next, it is demonstrated that higher-order many-body contributions can be computed using smaller basis sizes than used for the lower orders when a consistent accuracy in the calculation is targeted. Our findings are empirically validated using many-body perturbation theory and coupled-cluster calculations of
nuclei spanning a large portion of the
nuclear chart using two sets of
chiral two- and three-nucleon interactions. The results suggest that considerable computational savings can be obtained using many-body-order-dependent one-body basis sizes.
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All authors L. Zurek, U. Vernik, P. Demol, T. Duguet, M. Frosini, A. Tichai