Materials Science
FP-DeErr: Application-Oriented Error Decomposition for Foundation Potentials
Kiyan Amirian, Ramanuja Srinivasan Saravanan, Felix Adams et al. (+2 more)
Foundation potentials (FPs) have emerged as a new basis for atomistic modeling. While their evaluation using average energy and force errors often indicates near-DFT accuracy, their performance in practical computational studies remains inconsistent. While recent
benchmarks evaluate FPs on downstream computational tasks, the underlying errors that determine task success or failure are not always clear. Here, we develop FP-DeErr, an application-oriented error-decomposition framework that resolves FP errors according to the physically meaningful quantities, configurations, and computational stages governing specific tasks. Rather than averaging errors over an entire
dataset, FP-DeErr uses decomposed error metrics devised for physically meaningful quantities, focusing on the configurations where errors arise and matter most. We demonstrate FP-DeErr by evaluating multiple state-of-the-art FPs on three fundamental tasks: force prediction for atomistic simulations, energy ranking for substitutional and vacancy orderings, and ion/vacancy migration. These error-decomposition metrics resolve force errors among highly accurate, large-error, and far-from-
equilibrium atoms; relative-energy errors among competing orderings, phases, and compositions; and ion migration errors among endpoints and along-path errors. By identifying where FP errors arise, this error decomposition provides targeted guidance for FP development. FP-DeErr also provides an open
benchmark, evaluation code, and a public leaderboard for rigorous FP assessment.
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All authors Kiyan Amirian, Ramanuja Srinivasan Saravanan, Felix Adams, Charles E Schwarz, Yifei Mo
Plasma Physics
Novel approach to general curvilinear coordinates for plasma fluid applications
Federico D. Halpern Tess N. Bernard, Oleksandr Koshkarov and Ronald E. Waltz
In general geometry,
plasma fluid equations include nonlinear
geometric sources associated with fictitious forces, which pose significant challenges to computer simulations. We reformulate the
plasma fluid hierarchy to rigorously preserve geometry and conservation properties critical to numerical simulations, while concealing the
geometric sources. In their discrete form, the reformulated models conserve mass, angular momentum, and energy naturally, by simple analogy with the continuum equations. These conservation properties have minimal requirements in discrete space, namely, the anti-
symmetry of the first derivative and the orthogonality of the scalar and cross products. By decoupling
magnetic geometry, coordinate systems, and numerical discretization, this enables maximum flexibility while preserving physics fidelity. As a testbed, we apply the novel representation to the resistive magnetohydrodynamic system, which involves a complete set of curvilinear operations. We verify the correctness of the approach using steady state
liquid metal flows and the classic Orszag-Tang
vortex.
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Chemical Physics
cuSOAP: a GPU-accelerated Generator of Smooth Overlap of Atomic Positions Descriptor
Hongyu Yan, Yuqing Xia, Yong Wei et al. (+2 more)
The Smooth Overlap of Atomic Positions (SOAP) descriptor is one of the most widely adopted representations of atomic environments in molecular machine learning, but the cost of evaluating it and its derivatives remains a principal bottleneck of SOAP-based interatomic potentials, particularly at the large radial and angular basis sizes demanded by complex, multi-species condensed-phase environments. We present cuSOAP, a GPU-accelerated generator of atom-wise SOAP vectors and their analytic derivatives. Built on PyTorch, cuSOAP evaluates closed-form expressions or quadratures for the projection coefficients and their Cartesian gradients for Gaussian-type-orbital and
polynomial radial bases, through fused CUDA and Triton kernels that eliminate the multi-gigabyte intermediates of a naive tensor formulation. The package is a drop-in replacement for the CPU-based reference DScribe, reproducing its constructor signature, feature ordering, and output to within ${\sim}10^{-6}$, and accepts structures directly as Atomistic Simulation Environment (ASE) Atoms objects. On an NVIDIA Grace–Blackwell (GB200) node, a single Blackwell GPU generates the full descriptor-plus-Jacobian workload for a 1000-molecule water cluster up to two orders of magnitude faster than DScribe, i.e., from $13\times$ to $227\times$ across the entire $(n_{\max}, l_{\max})$ hyperparameter map, with the speedup growing with the angular band limit $l_{\max}$. Descriptor-only generation scales as $t \propto n^{1.34}$, close to linear, up to a million-atom water cluster, which is processed in 19.5s on one GPU and, through a shared-
memory multiprocessing driver, in 5.7s on the four GPUs of the node, demonstrating $\sim$90% parallel efficiency with no sign of saturation as devices are added. These results bring on-the-fly SOAP evaluation for large-scale condensed-phase simulation within reach.
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All authors Hongyu Yan, Yuqing Xia, Yong Wei, Minghan Chen, Hanning Chen
Medical Physics
A unified dielectric-tensor model of macular form birefringence and dichroism
Gary P. Misson, Dusan Sarenac, Dmitry. A. Pushin et al. (+1 more)
Optical anisotropy of the Henle fiber layer (HFL) underlies two macular polarization phenomena, form birefringence (the macular cross) and dichroism (Haidinger's brushes), which have conventionally been treated as unrelated. We model the HFL as a radial diattenuating retarder and derive a single complex dielectric tensor: effective-medium theory for parallel cylinders gives the real part, and cylindrical averaging of the measured transmembrane xanthophyll tilt gives the imaginary part. The birefringent slow axis is radial and the absorption axis tangential, perpendicular by structural necessity. The model reproduces measured dichroic ratios of 1.04–1.14 for a single calibrated oriented-pigment fraction, and supplies the input parameters for full electromagnetic treatments.
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All authors Gary P. Misson, Dusan Sarenac, Dmitry. A. Pushin, Shelby E. Temple
Nuclear Theory
Beyond Viscosity Matching: Microscopic Relaxation in Anisotropic Flow
Olga Soloveva
When a gas of scattering particles is disturbed, each angular harmonic of its velocity distribution decays at its own rate. Hydrodynamics, and with it the shear viscosity, depends on only one of these rates, the one for the quadrupole harmonic. A system that scatters only a few times before it stops interacting remembers all of them. This is the situation of small collision systems such as $p+p$, $p+$Pb and O$+$O, where kinetic models tuned to the same viscosity nevertheless predict different anisotropic flow. We show that this difference is not a model uncertainty but a measurement of the remaining rates: to first order in the number of collisions, ratios of flow responses equal ratios of relaxation rates, independently of the initial geometry. For the QCD collision kernel, where the rates also depend on momentum, we obtain the full spectrum of relaxation modes in closed form and show that dilute flow, viscosity, and late-time decay probe three different averages of it. A momentum-resolved kinetic solver confirms that the angular hierarchy is lost first at soft momenta and that the flow response settles at a value no single-rate model produces. The same structure governs two-dimensional electron and atomic
Fermi gases.
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Quantum Physics
Characterizing Privacy Risks of Quantum Machine Learning with Emergent Quantum-Native Access
Liou Tang, James Joshi and Ashish Kundu
Quantum Machine Learning (QML) has shown rapid advances by utilizing
quantum computing for machine learning tasks. Meanwhile, the
privacy risks accompanying QML is also starting to be studied, which inherit
privacy leakage channels from "classical" ML and also
quantum-unique risks. Existing work on
privacy-preserving QML largely focuses on a QML-as-a-service scenario, which generally assumes that the QML model owner provides only classical bit outputs to queries, while users (and adversaries) have only classical computing abilities. However, this view is increasingly challenged in a
quantum-native world of
quantum-capable users/adversaries, which may have access to both
quantum computing abilities and access to
quantum information output from service providers. In this paper, we aim to bridge this gap by examining membership inference attacks against QML models by demonstrating that increasing
quantum access and
quantum computing abilities provides provable theoretical
privacy leakage and empirical
adversarial gain. However, the probabilistic nature of QML introduces a gap between theoretical and empirical
adversarial advantage. These results show that existing research on
privacy leakage in QML models underestimates
privacy leakage in emergent
quantum-native access regimes, and we hope to establish a first step in examining potential
privacy leakages for QML in the
quantum-native world.
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Quantum Gases
Generating quantum error correcting codes from topological pre-thermal scars
William N. Faugno, Frank Barrows, Terry A. Loring et al. (+2 more)
Quantum many-body scars are rare nonthermal states embedded within otherwise thermalizing spectra, making them promising candidates for storing and manipulating
quantum information. However, a general framework that can both identify such states without prior knowledge of their microscopic scarring mechanism and determine when they enable a
quantum error correcting code has remained elusive. Here, we develop an end-to-end framework connecting nonthermal-state discovery to certifiable
quantum error correction using a many-body spectral localizer. By searching for states jointly localized in energy and a diagnostic observable in systems with a many-body grading
symmetry, the spectral localizer identifies candidate scars within dense many-body spectra in tandem with a topological index whose shifts determine their graded subspace. For suitable pairs of same-graded scars, the grading renders grading-odd errors exactly detectable, while their localization can suppress the logical action of sufficiently local grading-even error products, yielding an approximate Knill–Laflamme condition and an operator-
algebra quantum error-correction structure. We demonstrate the scar-identification framework in one- and two-dimensional density-difference-dependent bosonic models and in the PXP model, and explicitly construct the resulting approximate
quantum code in the one-dimensional bosonic system. Our results establish a systematic route from identifying nonthermal many-body states to exploiting them for protecting
quantum information, and position pseudospectral methods as a broadly applicable tool for discovering useful behaviors in interacting
quantum systems.
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All authors William N. Faugno, Frank Barrows, Terry A. Loring, Nathan Goldman, Alexander Cerjan
Materials Science
Bridging simulation length scales with cellular automata
John J. Karnes, Esteban D. Gadea, Shakkira Erimban et al. (+2 more)
Multiscale simulation requires coupling physics models that operate at different characteristic length and time scales, because no single method spans the range needed for most problems of interest. Moving to a coarser-grained representation unlocks longer length and time scales, but it discards the microscopic interactions that build morphology. A fine-grained model can be initialized from an arbitrary packing and left to self-assemble into a physically meaningful structure; a lower-resolution model cannot, and must inherit its starting configuration from a higher-fidelity simulation. The length scales accessible to the coarse-grained model are therefore set not by the coarse-grained method itself, but by the largest fine-grained configuration that can be affordably equilibrated. A representative example is the scale-up from particle-based molecular dynamics (MD) to a
lattice-based representation such as kinetic Monte Carlo (kMC). In this work, we present a cellular automata (CA) approach for generating arbitrarily large
lattice starting configurations. CA is a natural fit for this task: short-ranged local rules drive the
evolution of a
lattice, and their repeated application gives rise to emergent long-range order, thematically mirroring how short-ranged interactions in MD produce self-assembled morphology. We use a configuration from a higher-fidelity simulation as a training set and learn the CA rules from it via logistic regression. As a proof of principle, we develop these rules for a hydrated anion exchange membrane (AEM), generate new starting configurations, and
benchmark their performance in mesoscale kMC simulations against an MD-derived "ground truth." We then demonstrate the ability to generate substantially larger
lattices and show that their behavior in kMC is consistent with that of the smaller CA
benchmark configurations.
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All authors John J. Karnes, Esteban D. Gadea, Shakkira Erimban, Ignacio J. Bombau, Valeria Molinero
Soft Condensed Matter
Hidden amplitude and dynamical information in phase-separation spectra
Boliang Yu, Ruixin Zhou and Jiaxing Yuan
Framewise variance normalization removes fluctuation amplitude from an observation, but not from the dynamics that generate later patterns. The current normalized spectrum therefore need not determine its own future. We study this effect in three two-dimensional phase-separation models that change transport, add active driving, or suppress large-scale separation. For paired initial fields, their normalized spectra evolve identically in the linear regime. The restoring model provides an exact example: damping does not directly change how the normalized spectrum evolves when both equations are applied to the same field. It nevertheless changes the hidden amplitude, which alters the later nonlinear shape. An exact comparison separates the immediate effect of changing the equation from the effect of reaching a different state through earlier
evolution. It also reveals strong cancellation between these effects in the mobility and active models. As a practical test, spectral histories improve classification by about 4-6 percentage points at several later observation windows, although the gain depends on quench depth and spectral construction. Temporal spectra can therefore reveal dynamical consequences of information absent from every individual normalized frame.
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High Energy Physics (Phenomenology)
Agnostic search for a vector-like top partner at a lepton collider via the recoil mass technique
Higinio Valle, Cristina Oropeza Barrera and Oscar Ochoa-Valeriano
A study of the single production of a vector-like top partner $T$ at a $\sqrt{s}=3$ TeV $e^{+}e^{-}$
collider is presented, using a decay-mode and mass-agnostic event selection built around the
recoil mass observable. The analysis relies on fully simulated samples processed through a common reconstruction and event selection chain. The baseline selection is validated without beam polarization or initial-state radiation (ISR). The impact of more realistic running conditions, including ISR together with an $e^{-}$ beam polarization of $-80\%$, is then evaluated and the discovery reach is mapped as a function of the top partner mass $m_{T}$ and coupling strength $\kappa_{T}$. In the baseline scan, the estimated statistical significance rises above $3\sigma$ for the lowest
benchmark masses once $\kappa_{T}$ exceeds approximately 0.3.
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Plasma Physics
A Minimal Self-Consistent Model for the Nonlinear Dynamics of Asymmetric Capacitively Coupled Radio-Frequency Plasmas
Thomas Mussenbrock
We develop a minimal self-consistent lumped-element model for the nonlinear
radio-frequency dynamics of geometrically asymmetric capacitively coupled
plasmas. The fast electrical response is described by three dynamical variables: the powered-sheath charge, the blocking-capacitor voltage, and the discharge current. The periodic RF solution is coupled to stationary particle and energy balances, which determine the electron temperature and
plasma density from the operating conditions and the absorbed power. For an argon discharge, the model produces nonlinear current oscillations and a broad higher-harmonic response associated with the
plasma series resonance. Variation of the RF voltage leads to correlated changes in the harmonic spectrum, absorbed power, and
plasma density. Linearization about the periodic state relates the high-frequency response to the time-dependent differential sheath elastance. A moment-based effective elastance provides a compact estimate of the corresponding characteristic PSR frequency. The model thereby connects nonlinear RF dynamics and
plasma sustainment within a minimal self-consistent description.
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Mesoscale and Nanoscale Physics
Spectroscopy With Intelligent Feature Tracking for automated characterization of excited-state structure in semiconductor quantum dot devices
A. R. Huffman, Daniel Schug, Merritt Losert et al. (+6 more)
The characterization of excited-state structure in
semiconductor quantum dot (QD) devices is an important component of tuning them for
spin-
qubit operation. We present Spectroscopy With Intelligent Feature Tracking (SWIFT), a framework that combines machine-learning (ML)-assisted feature identification with physics-informed
geometric processing to extract energy-level splittings from pulsed-gate spectroscopy data. SWIFT isolates the relevant spectral features and exploits their characteristic geometry to reduce the two-dimensional spectroscopy analysis to a one-dimensional peak-detection problem. It further combines an ensemble-based confidence metric with sequential accumulation of rapid, low-SNR scans, allowing the inferred spectrum to be reevaluated as experimental evidence accumulates. Using Si/SiGe QD devices, we demonstrate SWIFT both offline and in real time, including automated tracking of QD excited states and lead resonances. Benchmarking on 255 manually labeled scans shows that SWIFT reduces the median splitting error to 0.05 mV from 0.11 mV for a classical baseline, with the largest improvement on lower-quality measurements. These results provide a path toward incorporating excited-state spectroscopy into autonomous QD characterization, tuning, and optimization, which will be essential in large-scale
quantum dot devices.
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All authors A. R. Huffman, Daniel Schug, Merritt Losert, Sanghyeok Park, Daniel King, Yuna Chun, Giordano Scappucci, M. A. Eriksson, Justyna P. Zwolak
High Energy Physics (Theory)
Searching for Bell-CHSH-Violating Bose Operators
T. Newton and S. P. Sorella
We construct bounded Bell observables for a free scalar field in complementary spacetime wedges using measurable involutions of the spectral variable of a local canonical quadrature. These involutions yield wedge-local Hermitian
unitary operators that anticommute with a chosen bounded observable. For a cosine observable, we characterize the admissible translations and reflections and derive exact correlations at finite modular bandwidth. The affine-reflection construction yields a violation of the Bell-CHSH inequality of approximately 2.06.
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Astrophysics of Galaxies
Tracing the Hidden Molecular Gas in the Small Magellanic Cloud with SOFIA and APEX
K. Rodriguez-Ambler, R. Herrera-Camus, M. Rúbio et al. (+6 more)
In low-
metallicity environments, reduced
dust abundance weakens molecular cloud shielding against far-ultraviolet radiation, enhancing CO photodissociation and producing extended CO-faint or CO-dark molecular gas. The [CII] 158 $\mu$m line is a key tracer of these CO-faint phases. We characterize the multiphase origin of [CII] emission and quantify the CO-faint molecular gas fraction across several regions of the Small Magellanic Cloud (SMC), the nearest low-
metallicity ($\sim 0.2 Z_\odot$)
galaxy. We combine high spectral resolution SOFIA/GREAT and upGREAT [CII], APEX CO(2-1), and ASKAP+Parkes H I 21 cm data to decompose [CII] into its atomic and molecular contributions. On average, $(78\pm 1)\%$ of [CII] intensity originates from molecular gas and $(18\pm 1)\%$ from atomic gas. The [CII]-traced H$_2$ accounts for $(77\pm4)\%$ of the total molecular gas column density, indicating that the SMC molecular reservoir is dominated by CO-faint gas. We derive a H$_2$-to-CO conversion factor $X_{CO}\approx 8.9\times10^{20}$ cm$^{-2}$ (K km s$^{-1}$)$^{-1}$ on 4 pc scales in CO-emitting regions, 4.5 times the canonical
Galactic value. We find no significant correlation between the CO-dark fraction and either total column density or $\Sigma_{SFR}$, suggesting that the CO-faint fraction is primarily governed by
dust and gas shielding rather than current
star formation activity. Our results demonstrate that [CII] is the dominant tracer of molecular gas in the SMC and confirm the prevalence of an extended, stable CO-faint molecular phase in low-
metallicity environments.
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All authors K. Rodriguez-Ambler, R. Herrera-Camus, M. Rúbio, A. D. Bolatto, D. Riquelme-Vásquez, K. Jameson, C. Muñoz-López, E. J. Tarantino, J. Stutzki
Quantum Physics
Quantum lower bounds for convex optimization and real matrix-vector query problems
Andrew M. Childs
We (the author and the AI systems that did the heavy lifting) show that the
quantum query complexity of minimizing a convex function over a convex subset of $\mathbb{R}^n$ with evaluation and membership queries is $\tilde\Omega(n)$, nearly matching the best known upper bound. In particular, we show this even for quadratic minimization, which is equivalent to inverting an $n \times n$ real
matrix using
matrix-vector queries. We also show linear or nearly linear lower bounds on the
quantum query complexity of computing the trace, the sign of the determinant, and the magnitude of the determinant of a real
matrix in the
matrix-vector query model. We use a novel
quantum lower bound technique, the determinantal witness method, based on identifying a witness whose
Fourier transform vanishes on low-rank
matrices and that correlates well with the function being computed.
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Astrophysics of Galaxies
Reigniting the FUSE I: Star Formation in Massive Elliptical Galaxies
Michael Reefe, Michael McDonald, Eric Miller et al. (+1 more)
In this inaugural paper of our "Reigniting the FUSE" series, we present the data collection & reduction, methodology, and preliminary results for a comprehensive and homogeneous reanalysis of all 30 massive elliptical
galaxies that have archival far-ultraviolet (FUV) spectra with the Far Ultraviolet Spectroscopic Explorer (FUSE). We perform SED fitting to these spectra, with aperture-matched photometry from GALEX, SDSS, DES/DECaLS, 2MASS, and WISE, and construct a catalogue of high quality constraints on their
stellar masses,
star formation histories,
stellar and gas-phase
metallicities, and
dust opacities. As a part of this analysis, we have also compiled a comprehensive modern set of
stellar template libraries, with high resolution in the FUV, and broad coverage from $90\,\mathring{\rm A}$ - $1000\,{\rm \mu m}$ at lower resolution, which is made available through modified versions of FSPS and Python FSPS. We find strong evidence to suggest that the youngest
stars in these systems do not form out of recycled gas from the old
stellar populations, but instead are fueled either by gas cooling out of the hot circumgalactic/intracluster medium, or cool gas stripped from nearby or merging
dwarf systems. Future papers in this series will reexamine the O VI $\lambda\lambda$1032,1038 $\mathring{\rm A}$ emission in the context of the cooling flow problem.
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All authors Michael Reefe, Michael McDonald, Eric Miller, Thomas Brown
Instrumentation and Detectors
The DarkLight Experiment at TRIUMF
R. Alarcon, D. Almonte, M.I. Alstaty et al. (+60 more)
This paper reports on the commissioning of the DarkLight experiment at the ARIEL superconducting electron linear accelerator located at TRIUMF in Vancouver, Canada. DarkLight was designed to utilize the ARIEL electron beam to search for a new
boson, $A^\prime$, which preferentially couples to
leptons, with a mass in the range 13-17 MeV/$c^2$. Such a
boson could be produced via the $e^-~X\rightarrow e^-~X~A^\prime$ process, and the resulting $A^\prime\rightarrow e^+~e^-$ decay used to reconstruct the invariant mass of the $A^\prime$. The $e^+e^-$ pair is detected using a pair of
magnetic spectrometers. Each spectrometer is instrumented with two triple GEM detectors and a scintillating strip hodoscope to trigger the event readout. Electron beam energies between 10 and 30 MeV were used to commission the experiment with a 1$~\mu$m thick carbon target. With both spectrometer polarities set to select electrons, elastic and Møller scattering were used to examine detector performance and compare with predicted distributions from Monte Carlo simulations. Planned upgrades to the e-linac will allow searches to be made with beam energies up to 50 MeV using a 1$~\mu$m thick tantalum target.
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All authors R. Alarcon, D. Almonte, M.I. Alstaty, J. Azzi, R. Baartman, J.C. Bernauer, X. Braun, D. Ciarniello, C. Clabeaux, E.W. Cline, E. Corey, R. Corliss, W. Deconinck, A. Deshpande, J. Dilling, J. Dodge, D.H. Dongwi, C. Ekeman, E.A. Fielding, S. Frantzen, I. Friščić, G. Gelinas, S. Gelinas, K. Gill, A. Sabzevari Gonzalez, S. Gupte, D.K. Hasell, M. Hasinoff, B. Humphries, E. Ihloff, N. Jackson, D. Jayakodige, R. Kanungo J.E. Kelsey, O. Kester, M. Kohl, H.W. Koay, R. Laxdal, L. Levack, X. Li, W. Lin, C. Ma, A. Mahon, H. Merkel, J.W. Martin, L. Miller, R. Milner, K. Olchanski, K. Pachal, T. Planche, D. Preddy, S.D. Rädel, G. Randall, J. Redinger, D.A. Reiter, R. Richards, B. Scully, S. Shapiro, M. Suresh, C. Vidal, S. Wang, H. Witte, H. Yang, S. Yen
Geophysics
The tetragonal-cubic transition of davemaoite: Implications for lower mantle seismic anomalies
Yoshiyuki Okuda, Bin Chen, Juliana Peckenpaugh et al. (+5 more)
Davemaoite (CaSiO3 perovskite) is the third most abundant mineral in Earth's lower mantle and a dominant phase in subducted oceanic crust. Its
crystal structure is distorted (tetragonal or orthorhombic) at ambient conditions but is considered to transform to cubic at high temperatures. Previous experiments reported low, nearly pressure-independent transition temperatures (approximately 600 K), demonstrating a long-standing discrepancy with theoretical predictions that mostly exceed 1000 K. Here, we determine the phase stability and thermal equation of state of CaSiO3 davemaoite and its titanium-bearing solid solution [Ca(Si0.75,Ti0.25)O3] under simultaneous high-pressure and high-temperature conditions using a
laser-heated diamond anvil
cell combined with synchrotron X-ray diffraction. We find that the tetragonal-to-cubic transition occurs at substantially higher temperatures than previously reported, with the titanium substitution further stabilizing the tetragonal phase and shifting the transition boundary to even higher temperatures. These findings indicate that CaSiO3 davemaoite in subducted oceanic crust likely undergoes its ferroelastic transition in the mid-lower mantle, whereas Ti-rich davemaoite may remain tetragonal throughout most of the lower mantle, transforming to cubic near the core-mantle boundary. Our results demonstrate that the compositionally dependent phase behaviour of davemaoite can account for the seismic anomalies observed in both the mid-lower mantle and the lowermost mantle.
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All authors Yoshiyuki Okuda, Bin Chen, Juliana Peckenpaugh, Keng-Hsien Chao, Saori Kawaguchi-Imada, Hirokazu Kadobayashi, Zhenxian Liu, Dongzhou Zhang
Quantum Physics
Kerr Induced Control of Synchronization and Quantum State Recovery in a Driven van der Pol Oscillator
Amir Hossein Houshmand Almani, Ali Mortezapour and Alireza Nourmandipour
We investigate how Kerr nonlinearity modifies
quantum synchronization in a squeezed
quantum van der Pol oscillator. We show that the Kerr interaction produces an amplitude-dependent frequency shift that drives a saddle-node bifurcation, transforming the classical phase-space structure from bistable to monostable dynamics. In the
quantum regime, this transition manifests as systematic frequency pulling and spectral broadening, while the steady-state Wigner function reveals a continuous correspondence between the
quantum state and the semiclassical attractor despite finite
quantum fluctuations. By constructing global synchronization phase diagrams in the squeezing–Kerr parameter space, we uncover a remarkably linear dependence of the critical squeezing strength required to maintain phase locking on the Kerr nonlinearity. We further demonstrate that the synchronization boundary does not coincide with the crossover between super- and sub-Poissonian
photon statistics, showing that synchronization and
photon-number statistics characterize distinct aspects of the
quantum steady state. These results provide quantitative design principles for controlling
quantum synchronization through Kerr nonlinearity, with potential relevance to trapped-ion, superconducting-
circuit, and optomechanical platforms.
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Chemical Physics
Differentiable Solvation Shell Model for Rational Electrolyte Design
Hancheng Zhao, Hongyi Lin, Celia Kelly et al. (+1 more)
Tailoring Li+ solvation structures has emerged as a promising design principle across multiple Li metal battery (LMB) electrolytes, with localized high concentration electrolytes (LHCE) emerging as a leading candidate. However, rational design of these electrolytes remains limited by a poor quantitative understanding of how molecular properties govern Li+ solvation shell composition. Here we introduce a mean field modeling framework, built on an Ising model, that predicts solvation shell composition from donor number (DN), acceptor number (AN), molar ratio, and molecular size. This framework is end-to-end differentiable, which enables parameterization directly from molecular dynamics (MD) solvation structures via gradient-based optimization. Focusing on LHCE, the model achieves 10.7% RMSE and R2=0.87 for shell composition, 2.3% RMSE on free solvent ratio, and further reproduces solvation trends in real LHCE electrolytes, at a fraction of MD's cost. Our model also shows good generalizability on other electrolyte systems in addition to LHCE. Analysis of its interaction terms shows that DN dominates Li+ solvation energetics, providing a thermodynamic basis for empirical DN-based design rules. We further demonstrate the model's design utility on the LiTFSI/tetraglyme (G4) system absent from training. The model identifies fluorobenzene (FB) as a promising diluent and predicts a salt-concentration window with anion-rich solvation shells and low free solvent, favorable for stable anion-derived SEIs and high oxidative stability, respectively. This prediction is validated by higher-fidelity MD. This work establishes an interpretable differentiable framework for predicting Li+ solvation shell composition, with potential to extend to other electrolyte classes.
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All authors Hancheng Zhao, Hongyi Lin, Celia Kelly, Venkatasubramanian Viswanathan
Mesoscale and Nanoscale Physics
A magneto-mechanical gyroscope with spintronic readout
Andrea Meo, Francesca Garesci, Pedro Bossi Nunez et al. (+10 more)
Gyroscopes are essential elements in
navigation, consumer electronics, robotics, and aerospace applications. Most micro electro-mechanical systems (MEMS) implementations rely on capacitive sensing mechanisms, which limit the dimensional scaling to the micrometer scale. In this work, we introduce a MEMS-like two-degree-of-freedom (2-DOF) gyroscope that exploits the rectification functionality of
magnetic tunnel junctions (MTJs) as its readout mechanism and as the transducer of the mechanical dynamics. Experimentally characterized MTJs have been used to calibrate and perform an experiment-informed design of the magneto-mechanical model combining micromagnetic theory with 2-DOF mechanical equations. We demonstrated that the output is linear with angular rate, and that the proposed device is able to extract the angular rate in dynamic cases exploiting a homodyne demodulation approach. The results open a path towards a compact, complementary metal-
oxide semiconductor (CMOS)-compatible readout pathway that relaxes reliance on tight capacitive gaps and motivates multi-physics designs of the device.
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All authors Andrea Meo, Francesca Garesci, Pedro Bossi Nunez, Maddalena Fiorentino, Teresa Natale, Ludovico Dindelli, Victor Lopez-Dominguez, Banibrato Sinha, Riccardo Tomasello, Francesco Dell'Olio, Pedram Khalili Amiri, Mario Carpentieri, Giovanni Finocchio
General Relativity and Quantum Cosmology
Fermionic Casimir memory from an anisotropic gravitational pulse
Celio R. Muniz and Herondy F. Santana Mota
We investigate the late-time energy deposited by a weak, spatially homogeneous anisotropic gravitational pulse in a massless Dirac field confined between two static parallel plates. The field satisfies MIT bag boundary conditions, while the prescribed geometry approaches Minkowski spacetime in both asymptotic time regions. Using a tetrad formulation, we show that the linear
spin-connection contribution cancels for the traceless anisotropy, leaving a coupling to the shear component of the Dirac stress tensor. The pulse produces real
fermion–antifermion pairs, whose deposited energy is evaluated through the corresponding Bogoliubov coefficients. Subtracting the production in unbounded space isolates a finite boundary-dependent contribution governed by the pulse duration relative to the characteristic spectral timescale set by the MIT gap. This contribution is negative in the adiabatic regime, where confinement suppresses excitations relative to the continuous free spectrum, and approaches zero from above in the impulsive limit. The resulting pressure correction is nonmonotonic and exhibits two sign changes, alternately reinforcing and reducing the ordinary attractive Casimir force. Unlike the bosonic
vacuum-polarization
memory previously obtained for the same class of backgrounds, the present effect is a dissipative fermionic
memory carried by gravitationally created pairs. Here,
memory denotes the persistent late-time modification of the
quantum state after the pulse has vanished.
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Cosmology and Nongalactic Astrophysics
Do DESI-DR2 BAO data imply a coupling of dark matter and dark energy?
Weiqiang Yang, Sibo Zhang, Dinorah Barbosa et al. (+3 more)
We revisit an interacting dark matter (DM) – dark energy (DE) model characterized by the interaction function $Q = \Gamma \rho_x$, where $\Gamma$ is a constant coupling parameter and $\rho_x$ is the energy density of DE. This type of interaction is independent of the Hubble rate or other external parameters, but depends only on the fundamental properties of DE, such as its equation of state (EoS), $w_x$. We pay special
attention to $w_x$ and study three distinct interacting scenarios distinguished by the nature of $w_x$, i.e. $w_x =-1$ (when DE corresponds to the
vacuum energy), $w_{x} < -1$ (when DE has a phantom behavior), and $w_x > -1$ (quintessential DE). We constrain all of them using the most recent cosmological
datasets, including CMB from Planck 2018, BAO from DESI DR2, and three compilations of SNIa (PantheonPlus, Union3, and DES-Dovekie). Our analyses reveal that evidence of interaction is supported in scenarios with $w_x =-1$ and $w_x < -1$ when all three
datasets are combined, but from the
Bayesian evidence analysis, $\Lambda$CDM remains favored over these interacting scenarios. Regarding the $S_8$ parameter, when $w_x > -1$, this interacting scenario leads to mildly lower estimates across all
datasets.
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All authors Weiqiang Yang, Sibo Zhang, Dinorah Barbosa, Marco Antonio Alvarez, Supriya Pan, Leila Graef
Quantum Physics
Robustness of Dynamical Casimir Effect-Induced Quantum Synchronization
Sebastián Francisquez, Fernando C. Lombardo and Paula I. Villar
The robustness of
quantum synchronization induced by the dynamical Casimir effect (DCE) is analyzed within a
circuit quantum electrodynamics (cQED) architecture consisting of two superconducting
qubits coupled to a shared, parametrically driven cavity. Using a Lindblad master equation approach, this study evaluates the impact of various decoherence channels (including
photon loss, relaxation, thermal excitation, and pure dephasing) on the resulting synchronization dynamics. The results demonstrate that DCE-induced synchronization persists under dissipation rates achievable in state-of-the-art superconducting platforms, confirming its experimental feasibility. Among the studied mechanisms, pure dephasing is identified as the dominant factor limiting the fidelity of the synchronized state. Furthermore, it is shown that in strongly dissipative regimes, the Pearson correlation coefficient may overestimate the degree of
quantum synchronization, as environmental relaxation can generate classical correlations that mimic synchronized behavior. These findings establish the parameter regimes necessary for observing genuine DCE-induced
quantum synchronization and provide practical guidelines for future cQED experiments.
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Quantum Physics
Minimum Cardinalities of Multipartite Unextendible Product Bases
Chenhao Wang
In
quantum information theory, the state space of a multipartite
quantum system is modeled by a tensor product. In the tensor-product space $\C^{d_1}\otimes\cdots\otimes\C^{d_p}$, a nonzero vector is a product state if it can be written as $\ket{\varphi_1}\otimes\cdots\otimes\ket{\varphi_p}$ with $\ket{\varphi_j}\in\C^{d_j}\setminus\{0\}$. An unextendible product basis (UPB) is a finite family of pairwise orthogonal product states such that no nonzero product state is orthogonal to all of them. UPBs play a key role in investigating
quantum entanglement and nonlocal phenomena. Finding a smallest UPB is a natural extremal problem: it asks how few pairwise orthogonal product states suffice to prevent any further product state from being added. The general minimum-size problem for UPBs has been studied for over two decades since the seminal work of Alon and Lovász. Let $f_m(d_1,\ldots,d_p)$ be the minimum cardinality of a UPB in the space, and let \(f_{LB}(d_1,\ldots,d_p)=1+\sum_{j=1}^{p}(d_j-1)\) be the natural lower bound. Alon and Lovász determined exactly when \(f_m\) attains the lower bound \(f_{LB}\), but the obstructed multipartite cases remained open in general. We prove a stabilization
theorem: for every non-all-
qubit system with $p\ge3$, whenever the natural lower bound $f_{LB}$ is unattainable, the true minimum is exactly $f_{LB}+1$. Precisely, if the number of even local dimensions $d_i$ is positive and even, and at least one local dimension is greater than two, then \(f_m(d_1,\ldots,d_p)=f_{LB}(d_1,\ldots,d_p)+1\). The proof is built on a unified graph-theoretic framework. Our result, together with earlier work, settles the minimum size problem for UPBs in all finite
quantum systems.
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Fluid Dynamics
Direct Numerical Simulation of Thermoacoustically Unstable Flames Via Non-Drifting Acoustic Delay Characteristic Boundary Conditions
Benjamin L. Cookman, Jack R. C. King, Raphaël C. Assier et al. (+1 more)
Thermoacoustic instability in premixed flames results from the coupling between the flame's heat release, as determined by combustion parameters, and surrounding acoustics, as determined by combustor geometry. A primary instability results in flame flattening as intrinsic flame instability modes are stabilised. Secondary thermoacoustic instability results in a parametric flame instability and drastic growth of acoustic amplitudes. Due to their relative expense, numerical simulations of these phenomena remain scarce. In this work, Direct Numerical Simulations (DNS) of thermoacoustically unstable idealised premixed flames in a tube with acoustically closed upstream and open downstream ends are presented. Results herein demonstrate nonlinear saturation of the primary instability as the flame flattens as well as an oscillating flame fingering characteristic of the unsteady Rayleigh-Taylor effect. To reduce computational cost, we perform DNS only on the region surrounding the flame. Acoustics at in- and
outflows are described using the Navier-Stokes Characteristic Boundary Condition (NSCBC) method to model their delayed reentry into the domain in a formulation referred to as the Acoustic Delay Characteristic Boundary Condition (ADCBC) method. A new Averaged Proportional and Integral Linear Relaxation (APILR) method is also introduced, which modifies the Classic Linear Relaxation (CLR) method to maintain time-averaged values of inflow velocity and
outflow pressure. Here, an integral control term is used to remove non-zero
equilibrium time-averaged inflow velocities which impinge control over flame position. Both new methods demonstrate their capability in inert and counterflow flames test cases. These methods enable the numerical simulation of combustion instabilities at significantly reduced computational expense.
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All authors Benjamin L. Cookman, Jack R. C. King, Raphaël C. Assier, Steven J. Lind
High Energy Physics (Theory)
Birth and Death in Two-color ABJM
Marco S. Bianchi
We solve exactly the leading
quantum deformation of the two-point metric of half-BPS operators in $U(2)\times U(2)$ ABJM theory at finite rank. In the natural coupling-independent Schur frame, its tree-normalized two-loop correction is a Jacobi operator on the chain of two-row Young diagrams. A ground-state transform maps it to a reversible birth–death process whose stationary distribution is the Plancherel measure conditioned on diagrams with at most two rows. Its eigenmodes are Racah
polynomials, its large-$n$ limit approaches radial Ornstein–Uhlenbeck dynamics, and an equivalent two-
spin description identifies the Jacobi operator with a restricted $SU(2)$ Casimir.
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Soft Condensed Matter
From agent-based dynamics to a kinetic theory of jellyfish swarms
Nicolas Perez, Erik Gengel, Zafrir Kuplik et al. (+1 more)
Massive jellyfish swarms observed at sea can extend over tens of kilometres and contain millions of individuals, yet the mechanisms governing their formation and large-scale dynamics remain poorly understood.
Agent-based models provide a framework for describing this dynamics based on jellyfish responses to ocean currents and environmental cues, but become computationally prohibitive when extended to large populations and spatial scales relevant to ocean circulation. Here we derive a continuous kinetic theory from an active-particle model of jellyfish motion. The resulting Fokker-Planck framework incorporates transport by prescribed currents,
stochastic reorientation, direct interactions and stimulated steering, allowing chemical signalling to be represented through a coupled field. We further derive a hydrodynamic closure for large swarms by exploiting the separation between fast orientational and slow spatial dynamics, yielding a reduced density equation suitable for implementation in ocean-current models. This framework provides a route from individual behavioural mechanisms to continuum descriptions of jellyfish populations and establishes a basis for constraining model parameters using observations and in-situ measurements. This approach offers a theoretical foundation for future numerical prediction of large jellyfish swarm formation and
evolution in realistic ocean flows.
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All authors Nicolas Perez, Erik Gengel, Zafrir Kuplik, Eyal Heifetz
Statistical Mechanics
Distribution of currents in a system of active particles with biased hops and Ising interactions
Evgeniy Khain, Shriram Ramesh and Vladimir Chernyak
We consider an ensemble of particles performing a biased random walk on a two-dimensional
lattice. Due to the adhesion between particles (nearest-neighbor Ising interactions), the probability of hopping depends on the number of neighbors and the strength of adhesive interaction. The asymmetry in the hopping directions leads to a macroscopic current of particles through the system. We theoretically compute the distribution of currents and verify the results in
stochastic particle simulations. To make theoretical progress, one has to determine the probabilities of various particle configurations such as single particles, pairs, and different configurations of three-particle clusters. These probabilities are theoretically derived by formulating rate equations for the concentrations of various structures resembling Becker-Döring cluster equations. One intriguing finding is that the concentration of left-handed triplets is not equal to the concentration of right-handed triplets for non-zero asymmetry of hops and non-zero interaction between particles.
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Mesoscale and Nanoscale Physics
Gauge-covariant magnetic Bloch sums for general multiorbital Hofstadter models
Hao Shi, Tianyu Qiao, Wangqian Miao et al. (+3 more)
We formulate a unified treatment of the Hofstadter problem for general two-dimensional multiorbital Peierls tight-binding
Hamiltonians using a gauge-covariant
magnetic Bloch-sum basis. The construction retains the full Bravais geometry, arbitrary intracell orbital positions, and the original hopping table, so
lattice geometry, orbital
embedding, hopping range, and orbital content can all be handled within the same framework. At rational flux $\Phi/\Phi_0=p/q$, commuting
magnetic translations reduce the Peierls
Hamiltonian to minimal $qN_{\rm orb}\times qN_{\rm orb}$ blocks. Their dimension depends only on the flux through the primitive
cell, even when the fractional orbital coordinates are irrational. Electromagnetic gauge transformations act by
unitary conjugation within the construction and do not alter the required
magnetic supercell. We derive an explicit sparse
matrix in an oblique Landau gauge and establish the associated band counting, spectral redundancy, Chern-number formulation,
magnetic spatial constraints, and flux periodicity. Numerical examples include elementary
lattices, topological and flat-band models, and a spinful 22-band Wannier
Hamiltonian of monolayer $\mathrm{MoS}_2$, demonstrating a direct interface with first-principles electronic-structure calculations. As a complementary representation, we also derive exact generalized Harper equations from the same hopping data and relate them to the finite
magnetic-Bloch blocks.
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All authors Hao Shi, Tianyu Qiao, Wangqian Miao, Jin-Tao Jin, Quansheng Wu, Xi Dai