Mathematical Physics · Cross-listed from math.DG
Left-invariant Rarita-Schwinger fields on 3-dimensional Lie groups
Soma Ohno
We classify left-invariant Rarita-Schwinger fields on 2- and 3-dimensional Lie groups with left-invariant Riemannian metrics. The left-invariant Rarita-Schwinger equation is reduced to an algebraic system on the associated metric Lie
algebra. We show that, in dimension 2, non-trivial examples occur only in the flat abelian case. In dimension 3, apart from the flat abelian case, the only non-trivial examples occur on SU(2) equipped with a special left-invariant metric, for which the space of left-invariant Rarita-Schwinger fields has complex dimension 2. This metric is a Berger metric on $S^3$.
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Earth and Planetary Astrophysics
Discovery of an Eccentric Hot Super-Jupiter Leaving the Transiting Geometry of the Early-A-type star TOI-1355
Noriharu Watanabe, Norio Narita, Akihiko Fukui et al. (+20 more)
Hot Jupiters orbiting hot
stars ($T_\mathrm{eff} > 7000$ K) are suggested to have experienced high-eccentricity migration, often evidenced by the tendency for misaligned orbits, despite their circular orbits. In this paper, we present the discovery of TOI-1355 b: an eccentric ($e\sim0.22$) hot Jupiter with a mass of $m_{\mathrm{p}}\sim5.8M_J$ and a radius of $R_{\mathrm{p}}\sim 1.4R_J$ orbiting an A-type
star with a period of about $2.17$ days, identified from the TESS transit survey and subsequent follow-up observations. We measured the
stellar parameters using the data from the high-resolution spectrograph Seimei/GAOES-RV and obtained the planetary parameters from the photometric data acquired by TESS and ground-based
telescopes. This is one of the rare eccentric hot Jupiters around hot
stars. This system could be undergoing high-eccentricity migration. We detected nodal precession by measuring the change in its impact parameter. This implies that its transit will no longer be observable from the middle of 2033. Nevertheless, TOI-1355 b is anticipated to be a compelling target for future atmospheric observations, given the hint of atmospheric variability detected in this study.
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All authors Noriharu Watanabe, Norio Narita, Akihiko Fukui, Bun'ei Sato, Keisuke Isogai, John H. Livingston, Jerome P. de Leon, Daniel Huber, Yugo Kawai, Yuya Hayashi, Masashi Omiya, Hideyuki Izumiura, Akito Tajitsu, Keivan G. Stassun, Eric Girardin, Giuseppe Marino, Antonio Frasca, Giovanni Catanzaro, Javier Alonso-Santiago, Manfred Raetz, Stephanie Striegel, Nobuhiko Kusakabe, Motohide Tamura
Astrophysics of Galaxies
Candidates for the most [$O_{III}$] $\lambda5007$-luminous planetary nebula in the Milky Way. I. Integrated light properties of NGC 6572, NGC 6884, and M 1-71
Azlizan A. Soemitro, Martin M. Roth, Jeremy R. Walsh et al. (+3 more)
The bright-end cutoff of the planetary nebula luminosity function (PNLF) serves as an extragalactic standard candle. However, the physical properties of planetary nebulae (PNe) at the PNLF cutoff have been studied only in nearby
galaxies, where the PNe appear mostly as point sources.
Galactic PNLF is further poorly constrained, primarily due to uncertainties in
Galactic PN distances. Following a recent
Galactic PNLF survey based on
Gaia distances, we aim to characterise PN candidates at the
Galactic PNLF cutoff. We observed three PN candidates at the
Galactic PNLF cutoff using the Potsdam Multi-Aperture Spectrophotometer (PMAS). We determined their chemical abundances and constructed photoionisation models to derive the central
star luminosity (L) and effective temperature (Teff). We constrained the central
star masses and most likely distances consistent with the prediction of
stellar evolution models. Using these distances, we determined the absolute magnitude M5007. PNe of our sample are located within the top 1 mag of the
Galactic PNLF (-4.20 < M5007 <-3.60), with similar nebular properties and a narrow progenitor mass range (1.30-1.75 Msolar). The measured extinction is mostly dominated by the foreground
Galactic extinction. The trend between the circum-nebular extinction and central
star mass of our PNe is in agreement with those derived in the Large Magellanic Cloud (LMC) and M31. All PNe in our sample exhibit weak-emission line
star (wels) features in their spectra, but we confirmed that some of these lines originate from the nebula. The PNe are similar in terms of their nebular properties and evolutionary stage. Their characteristics are also consistent with the most [OIII]5007-luminous PNe in the LMC and M31. We demonstrate the importance of circum-nebular extinction and the initial-final mass relation (IFMR) to understand the universality of PNLF as a standard candle.
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All authors Azlizan A. Soemitro, Martin M. Roth, Jeremy R. Walsh, Ana Monreal-Ibero, Brigitte G. A. Pruijt, Nicholas Chornay
Materials Science
Fresnel diffraction imaging of surface nanostructure using coherent resonant X-ray scattering
L. Burgard, C. Neupane, A. Balodhi et al. (+9 more)
We investigated surface nanostructures on an antiferromagnet MnBi$_2$Te$_4$ using a novel imaging technique, direct (real)-space and real time coherent X-ray imaging (direct-CXI). This technique has provided new insights into
antiferromagnetic textures, including the formation of anti-phase
antiferromagnetic (AFM) domains and thermal dynamics of AFM domains and domain walls. While this method produces real-space images of AFM textures without requiring a complex imaging
retrieval process, its underlying imaging mechanism has not been fully understood, limiting a deep understanding of AFM textures and the information they contain. By investigating the well-defined structural characteristics of the nanostructures fabricated on MnBi$_2$Te$_4$, we elucidate the imaging principle of this novel technique. We find that the observed images can be well explained by Fresnel diffraction integral. Using a simple model from classical optics, our calculations successfully reproduce the experimentally observed images of the nanostructures. This demonstrates that direct-CXI not only provides straightforward real-space imaging but also contains phase information through its Fresnel diffraction integral.
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All authors L. Burgard, C. Neupane, A. Balodhi, S. Bista, S. Butun, R. Jangid, A. Barbour, N. Basit, D. F. Agterberg, M. Weinert, C. Mazzoli, M. G. Kim
Quantum Physics
Exact certification of a positive-order Rényi additivity violation for an explicit channel pair
Artus Krohn-Grimberghe
Cubitt, Harrow, Leung, Montanaro, and Winter (CHLMW) exhibited an explicit pair of
quantum channels whose minimum output Rényi
entropy is nonadditive at order zero, and reported numerical violations at positive orders close to zero. Their paper states that a semidefinite-programming argument yields a rigorous positive-order interval for the same example, without printing the endpoint or a verifiable certificate; a recent paper by Leung, Lovitz, and Wu records that for this pair "no rigorous endpoint was obtained". We close that gap for the trace-preserving normalization of the printed pair fixed in Section 2. Small rational witness
matrices prove that every output of either channel has all
eigenvalues between $301/100000$ and $2/3$; a single explicit entangled input has an exact rational joint output spectrum of rank eight; and two independent elementary interval arguments turn these three facts into a proof of strict additivity violation, $S_p^{\min}(\mathrm{N}_R\otimes\mathrm{N}_{\bar S}) < S_p^{\min}(\mathrm{N}_R)+S_p^{\min}(\mathrm{N}_{\bar S}),$ for every real order $0<p\le 1/22$. Every step of the verification reduces to comparisons of integers, and the complete certificate is a few small rational
matrices that a reader can check with a short program – or, for any single order, by hand. To our knowledge, consistent with the assessment of Leung, Lovitz, and Wu, this is the first printed, computer-verifiable certified positive-order endpoint for this explicit pair. We claim no novelty for the phenomenon or for the
eigenvalue-floor mechanism, both due to CHLMW, and no optimality of the endpoint.
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Astrophysics of Galaxies
Diffuse Dwarf Galaxies in Galaxy Clusters: I. Stellar Populations and Radial Gradients
Arsen Levitskiy, Duncan A. Forbes, Jonah S. Gannon et al. (+5 more)
We use Keck/KCWI spectroscopy to study one ultra-diffuse
galaxy (UDG) and five Nearly-UDGs (NUDGEs) in the Perseus cluster, together with an additional UDG in the Coma cluster. As the first paper in a series, we focus on the global and radial
stellar population properties of our sample. We find that these
galaxies host intermediate-to old
stellar populations, with typical ages of ~7 Gyr, low
metallicities ([M/H]$\simeq$ -0.9 dex), and enhanced [Mg/Fe] abundances (~0.3 dex), consistent with previous studies. Six
galaxies lie within the scatter of the present-day mass-
metallicity relation (MZR), whereas the Coma UDG (DF11) is more consistent with the MZR of high-z
galaxies (z ~ 2). We find no strong correlation between global
stellar population properties and cluster infall parameters, suggesting that any environmental impact is not easily traceable through integrated
stellar populations. We go one step further and measure radial gradients for three
galaxies. Two show flat age and mildly negative
metallicity gradients, similar to classical
dwarfs, while one shows a rising
metallicity profile as recently found in other UDGs. Comparing with classical
dwarfs, we find a continuous correlation between
metallicity gradient and globular cluster (GC) richness, where more GC-rich systems tend to show rising profiles. We propose that preferential
tidal disruption of GCs in the inner regions of
galaxies naturally produces rising
metallicity profiles, unlike GC-poor classical
dwarfs. This mechanism, potentially coupled with strong
stellar feedback from early concentrated
star formation, may explain the unusual rising
metallicity profiles observed in GC-rich UDGs/NUDGEs.
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All authors Arsen Levitskiy, Duncan A. Forbes, Jonah S. Gannon, Yimeng Tang, Anna Ferré-Mateu, Aaron J. Romanowsky, Jean P. Brodie, Warrick J. Couch
High Energy Physics (Phenomenology)
From the universal Lindblad equation to Boltzmann equations: in-QGP quarkonium dynamics
Aoumeur Daddi Hammou and Pol Bernard Gossiaux
Recently, a set of coupled singlet-octet universal Lindblad equations (ULEs) was derived within the framework of non-relativistic QCD (NRQCD) to describe quarkonium dynamics in the
quark-
gluon plasma (QGP). These equations provide a unified
quantum description spanning the
quantum Brownian and
quantum optical regimes. In this work, we further develop this framework and establish its connection with semiclassical transport. We first derive the universal Lindblad equations within the potential non-relativistic QCD (pNRQCD) effective field theory and show that they coincide with the small-dipole limit of the NRQCD ULEs. We then derive the semiclassical limit of the NRQCD ULEs, obtaining a set of coupled singlet-octet Boltzmann equations. To our knowledge, this is the first derivation of Boltzmann transport equations directly from the universal Lindblad framework. The resulting equations are valid beyond the small-dipole approximation, allowing the
evolution of heavy-
quark pairs from compact to widely separated configurations. Taking their small-dipole limit allows a direct comparison with the Boltzmann equations of Yao et al. [Phys. Rev. D 99, 096028 (2019)], which were derived within pNRQCD from the Davies secular equation, relying on the rotating-wave approximation (RWA). While the singlet equations are found to be in near-complete agreement, the octet equation contains an additional collision term describing transitions within the continuum of octet scattering states, which is absent from the RWA-based derivation. Finally, we derive the leading
quantum correction to the singlet Boltzmann equation. Our results establish a more general and systematic theoretical foundation for the semiclassical transport description of quarkonium in the QGP.
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Instrumentation and Methods for Astrophysics
The Roman Coronagraph Community Participation Program: calibration strategy for the Mueller matrix using on-sky sources
Toshiyuki Mizuki, Justin Hom, Bertrand Mennesson et al. (+14 more)
The Nancy Grace Roman Space
Telescope Coronagraph Instrument will provide space-based polarimetric observations of circumstellar disks and exoplanetary systems. Accurate reconstruction of the linear polarization fraction requires calibration of the instrumental Mueller
matrix using polarized and weakly polarized standard
stars. We constructed a candidate catalog by combining published optical polarimetry with
Gaia DR3 astrometry and photometry and selected separate samples for coronagraphic calibration observations and observations using a neutral-density filter. Precursor $VRI$-band polarimetry of 18 faint candidates was obtained with HONIR on the 1.5-m Kanata
telescope. The wavelength dependence of their normalized Stokes parameters was modeled using the Serkowski law to predict their polarization properties in \cgi\ Bands~1 and 4, and 2 sets of 3 calibrators were selected for the 2 calibration scenarios. We then estimated the achievable LPF reconstruction accuracy using Monte Carlo simulations that include uncertainties in the calibrator polarization properties, photometric noise, and residual detector-response errors. A dithered observing configuration was also simulated to reduce differential detector-response errors among the calibrators. The current estimates indicate LPF reconstruction errors at the few-percentage-point level, with a small bias arising from treating a weakly polarized calibrator as unpolarized. Finally, we present progress toward an end-to-end test using corgisim and corgiDRP, including successful processing of simulated
datasets from Level~1 through Level~2b.
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All authors Toshiyuki Mizuki, Justin Hom, Bertrand Mennesson, Ramya M. Anche, Maxwell A. Millar-Blanchaer, Vanessa P. Bailey, Koji Kawabata, Mitsuhiko Takeuchi, Motohide Tamura, Naoshi Murakami, John Livingston, Jason J. Wang, Schuyler G. Wolff, Guillermo Gonzalez, Eric Shen, Tsutsumi Nagai, Taichi Uyama
Optics
Machine Learning-Assisted Analysis and Inverse Design of Prism-Based Surface Plasmon Resonance Sensors
R. Runthala, S. Murai and P. Arora
In this work, we demonstrate a data-driven machine learning (ML) framework for the efficient design and optimization of Kretschmann-configuration-based surface plasmon resonance (SPR) sensors. A physics-based
dataset was generated using a MATLAB-based transfer
matrix method (TMM), covering diverse material properties, layer thicknesses, and multilayer configurations. Optical properties and layer thicknesses were used as input features, while figure of merit (FOM) and minimum reflectance (Rmin) were the target performance parameters. Four ML models, namely CatBoost, XGBoost, LightGBM, and multilayer perceptron (MLP), were benchmarked using R2, mean absolute error (MAE), and root mean squared error (RMSE). The framework integrates ML benchmarking, SHAP explainability, robustness analysis, and optimization-driven inverse design. SHAP-weighted perturbation experiments assessed the model's robustness to input variations. Four optimization
algorithms were employed for inverse sensor design, followed by an analysis of parameter recovery and performance. The optimizers were also evaluated using an independent forward-design task, in which repeated runs converged on a common configuration. The optimized designs agreed closely with direct TMM calculations, with FOM errors of 0.6-0.9 percent and Rmin errors below 0.7 percent. The ML models achieved R2 values greater than 0.99 while reducing computational cost from seconds to milliseconds, corresponding to an acceleration of approximately 10^3 to 10^4 times compared with direct TMM simulations. Overall, the results demonstrate that physics-based surrogate ML models combined with explainability and optimization provide a computationally efficient and interpretable framework for rapid SPR sensor analysis, inverse design, and optimization.
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General Relativity and Quantum Cosmology
Ostrogradsky's Theorem is Incompatible with Background Independence in Quantum Gravity
Ken-ji Hamada
Ostrogradsky's
theorem shows that higher-derivative dynamical systems inevitably yields a
Hamiltonian featuring a ghost mode that is unbounded from below. However, we argue that this
theorem is inapplicable to gravitational systems, as the
Hamiltonian constraint, which encodes background independence by dictating that the total
Hamiltonian vanishes, holds strictly. The ghost mode obeying this constraint constitutes an indispensable component in the construction of space and time. Nevertheless, it should be underscored that the use of the weak-field (graviton) approximation, being a background-dependent scheme presupposing the existence of absolute time, invokes this
theorem; consequently, it is allowed only in the domain below the Planck scale, where second derivative terms dominate.
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Soft Condensed Matter
Resonant Untrapping of Active Polymers in Breathing Lattices
Yihang Sun, Yixiang Li, Tsvi Tlusty et al. (+1 more)
In crowded environments, active
polymers can trap themselves by winding into long-lived conformations. We show that fluctuations of the surrounding confinement can resonantly accelerate escape from these self-generated traps. Brownian dynamics simulations of a driven semiflexible chain in a breathing obstacle
lattice reveal intermittent switching between a compact rotating spiral and an extended translating state. Long-time
diffusion increases by up to two orders of magnitude when the environmental fluctuation rate becomes comparable to the spiral's intrinsic relaxation rate. The enhancement persists under
stochastic fluctuations, showing that coherent periodic forcing is not required. Activity creates a second optimum: it promotes escape once favorable conformations form, yet at strong drive stabilizes the spiral and suppresses their formation. Resonant untrapping thus provides a general mechanism by which fluctuating environments regulate transport through barriers generated by internal conformational dynamics.
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All authors Yihang Sun, Yixiang Li, Tsvi Tlusty, Guolong Zhu
Medical Physics
LV-CARE-Diff: A Conditional Anatomy-Aware Diffusion Model for Left Ventricular Shape Reconstruction and Function Quantification from Ultra-Sparse Cine Slices
Xinwang Li, Yu Lian, Bowei Liu et al. (+5 more)
Left ventricular functional quantification is an essential examination and is routinely performed using cardiovascular
magnetic resonance (CMR) cine imaging. However, conventional CMR cine protocols require the acquisition of multiple short-axis (SAX) slices to cover the entire left ventricle (LV) along with two long-axis (LAX) slices, which is time-consuming and places a considerable burden on patients who are unable to sustain repeated breath-holds, limiting its suitability for large-scale early screening. In this study, a Conditional Anatomy-Aware
Diffusion Model (LV-CARE-Diff) was developed using a coarse-to-fine strategy to reconstruct the complete LV shape from ultra-sparse cine slices, namely three short-axis and two long-axis slices, with the aim of accelerating CMR cine examination. LV-CARE-Diff employs a 3DUNet to generate a coarse initial shape, which is subsequently refined through a residual
diffusion model. A condition-guided input incorporating imaging plane orientation and positional metadata was constructed to enable spatial awareness, and a multi-objective training strategy jointly supervising shape, function, and anatomy was incorporated to guide high-fidelity reconstruction. LV-CARE-Diff was compared against a standalone 3DUNet, a standalone
diffusion model, and a 3D UNet with
diffusion-based refinement. Testing results indicated that complete LV shape could be robustly reconstructed by all deep learning models, with the highest reconstruction performance achieved by the proposed LV-CARE-Diff. Deep learning models reconstructing LV shape from sparse cine slices preserved 96% of functional quantification accuracy while reducing imaging time by 73%. The LV-CARE-Diff framework established in this study enables ultra-sparse cine acquisition to shorten CMR examination duration without sacrificing quantitative functional accuracy.
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All authors Xinwang Li, Yu Lian, Bowei Liu, Yifei Jiang, Jingjing Xiao, Haiyan Ding, Xiangchuang Kong, Rui Guo
Instrumentation and Methods for Astrophysics
The Roman Coronagraph Community Participation Program: early calibration plan and pilot observation of a companion
Julien H. Girard, Eric Cady, Neil T. Zimmerman et al. (+42 more)
Roman is set to launch in weeks! The Coronagraph Instrument - technology pathfinder for future direct imaging missions - is ready to fly too. According to predictions, laboratory tests and high fidelity simulations, it will open a new contrast regime enabling the imaging of mature,
giant planets in visible reflected light. The Community Participation Program is responsible for preparing a comprehensive observing program with associated data processing software and calibrations. We give a brief update about the on-going "baseline" calibration plan for the first months. Additionally, we describe a pilot program aiming for the
stellar companion HD 29992 B at moderate ~1e-5 to ~1e-6 Band 1 (575 nm) contrast, to be carried out as soon as the instrument is operational. The idea is to generate a canonical data set with a self luminous companion that is easily recoverable. This functional checkout will be precious to best prepare our community, exercise our calibration plan and suite of tools.
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All authors Julien H. Girard, Eric Cady, Neil T. Zimmerman, Clarissa R. Do Ó, Jingwen Zhang, Guillermo Gonzalez, Bijan Nemati, Vanessa P. Bailey, Alexis Lau, Sophie Noiret, John Krist, Julia Milton, Marie Ygouf, Ramya M. Anche, Schuyler Wolff, Justin Hom, Amanda Chavez, Jason J. Wang, Maxwell A. Millar-Blanchaer, Jessica Gersh-Range, Matthias Samland, Macarena Vega-Pallauta, Wolfgang Brandner, Toshiyuki Mizuki, Masayuki Kuzuhara, Susan Redmond, Kevin Ludwick, Jaren N. Ashcraft, William O. Balmer, Rusland Belikov, Beth Biller, Sarah Blunt, Ellis Bogat, Oscar Carrión-González, Gael Chauvin, Alexandra Z. Greenbaum, Sebastiaan Haffert, Jim Ingalls, Brian Kern, Bertrand Mennesson, Laurent Pueyo, Dmitry Savransky, Dan Sirbu, Peter Williams, Chen Xie
Optics
Spectral design of confining optical structures by supersymmetry techniques
Samantha Cervantes-Neri, Zulema Gress-Mendoza, Daniel O-Campa et al. (+2 more)
In this work, we apply supersymmetric transformations to an optical medium with quadratic index distributions on both transversal coordinates defining an
elliptic profile. In particular, we implement first- and second-order transformations to construct new multi-parametric gradient index patterns that may host one or two subsidiary guided modes with a wide range of spectral properties and transversal intensity and phase distributions. These transformations may be continued up to an arbitrary order enabling the possibility to control the spectral and propagation properties of light beams.
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All authors Samantha Cervantes-Neri, Zulema Gress-Mendoza, Daniel O-Campa, Erik Díaz-Bautista, Sara Cruz y Cruz
Optics
Inductively Scalable, Single-Step Neural Surrogates for Wave-Scattering Inverse Problems
Charles Dove and Laura Waller
Neural network surrogates are an emerging alternative to traditional electromagnetic wave simulators like finite-difference time-domain (FDTD); their goal is to replace rigorous physical simulations with pre-trained neural networks that solve wave-scattering forward and inverse problems orders of magnitude faster. However, nonrecurrent, single-step surrogates have scaled only to a few tens of simulation variables. Here, we show that this barrier can be overcome by dynamically generating salient training examples during training, rather than randomly sampling the large space of possible examples. We introduce an
algorithm that runs in parallel with surrogate training, using gradient ascent to search refractive-index and source configurations for cases where the surrogate disagrees with a full-wave ground-truth simulator. We also use source and ground-truth normalization with an evolving replay
dataset to stabilize and accelerate learning. Using this approach, we train a fast, single-step surrogate for two-dimensional wave scattering with up to 41,772 controllable variables, including dense, freely configurable grids of refractive indices and complex-valued sources. The resulting neural surrogate is robustly accurate across diverse structured and unstructured examples and generalizes inductively to larger domains, reaching over 3 million controllable variables without retraining, a $73.8\times$ increase. We demonstrate the surrogate on large-scale forward simulations and inverse design of freeform beam splitters and gradient-index (GRIN) lenses up to 98 wavelengths wide, showing comparable or better performance than FDTD-based designs, with speedups from $1.29\times$ to $26.5\times$. These results demonstrate a practical path toward fast, robustly accurate, inductively scalable neural simulators for photonic inverse design and other wave-scattering inverse problems.
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Chemical Physics
Temporally Distinguishing Photocatalytic Dynamics
Catherine J. Fabiano, Shan Deneen, Yigao Yuan et al. (+4 more)
Light can induce both photothermal and nonthermal catalytic activity in plasmonic nanoparticles, but the extent, timescale, and efficacy of these two mechanisms remain unresolved. Here we introduce pump-pump photocatalysis, an adaptation of ultrafast excitation correlation spectroscopy in which incident
laser pulses are split into two spatially and energetically equivalent pulses separated by a variable time delay. For a given reaction and catalyst, time-sensitive nonlinear enhancements in photocatalytic activity may be distinguished from time-insensitive responses as a function of time delay, pulse power, excitation wavelength, applied temperature, reactant pressure, and pulse asymmetry. In this way, the timescales of photothermal and nonthermal activity of any photocatalyst may be monitored on sub picosecond to nanosecond timescales, and the conditions for optimal chemical reactivity may be discovered. Here we report ultrafast measurements of the ammonia decomposition reaction using a Cu-Ru
antenna-reactor photocatalyst. Photothermal contributions exhibit little sensitivity to pulse delay, while nonthermal contributions are most apparent at low excitation intensity, moderate temperatures, and sub-nanosecond timescales. Here, nonlinear, nonthermal mechanisms enhance H$_2$ production by a factor up to eleven compared to when pulses overlap. This technique may be used to provide unprecedented in operando diagnostics and control of any photocatalyst for any chemical reaction. Most importantly, these measurements allow us to ascertain the optimal distribution of light to maximize photocatalytic activity.
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All authors Catherine J. Fabiano, Shan Deneen, Yigao Yuan, Luke Kay, Peter Nordlander, Naomi J. Halas, Henry O. Everitt
Plasma Physics
The FLARE Facility
Hantao Ji, Jongsoo Yoo, Peiyun Shi et al. (+53 more)
The Facility for Laboratory Reconnection Experiments (
FLARE) has been constructed to study
magnetic reconnection in multiple X-line regimes relevant to space, astrophysical, and fusion
plasmas. Building upon the successful design of the
Magnetic Reconnection Experiment (MRX),
FLARE features a larger physical volume, stronger
magnetic fields, and an independent ohmic heating drive to significantly extend the accessible parameter space, targeting Lundquist numbers up to S ~ 10^5 and normalized system sizes up to \lambda ~ 10^3. This paper details the facility's core engineering components, including the primary
vacuum vessel, internal flux cores, highly segmented external coil systems, modular capacitor banks, and the safety interlock and control architecture. An initial diagnostic suite is presented, comprising high-resolution 2D
magnetic probe arrays, triple Langmuir probes, a fully fiber-coupled interferometer, ion Doppler spectroscopy, and fast camera imaging. Initial operations demonstrate the device's experimental flexibility and reliability, successfully executing symmetric push-pull reconnection, spheromak merging, and asymmetric downstream configurations. Currently operating within "Stage 2.5" with S ~ 2,500 and \lambda ~ 60 for anti-parallel reconnection,
FLARE provides immediate access to the multiple X-line regimes. Planned hardware upgrades, advanced diagnostic additions, and integration with fully kinetic simulations will further expand its capabilities as it transitions into a collaborative user facility for the broader
plasma science community.
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All authors Hantao Ji, Jongsoo Yoo, Peiyun Shi, Euichan Jung, Kush Maheshwari, Adam Robbins, Sunghyun Son, Adam Stanier, Yang Ren, Sayak Bose, Dylan Corl, Keith Corrigan, Robert Cutler, William Daughton, Robert Ellis, Geoffrey Gettelfinger, Ronald Hatcher, Philip Heitzenroeder, Frank Hoffmann, Jonathan Jara-Almonte, Michael Kalish, Thomas Kozub, Enrique Merino, Weiguo Que, Benjamin Smith, John Wallace, Xin Zhao, Sofia Avrutsky, Neal Crocker, Seth Dorfman, Yuka Doke, Corina Dunn, William Fox, Boting Li, Xiaocan Li, Clayton Myers, Shohgo Okazaki, Joshua Pawlak, Tongnyeol Rhee, Byonghoon Seo, Taiju Suzuki, Yang Zhang, Stuart Bale, Amitava Bhattacharjee, Troy Carter, Chuanfei Dong, James Drake, Jan Egedal, Erik Gilson, Michiaki Inomoto, Jonathan Menard, Yasushi Ono, Stewart Prager, John Sarff, Hiroshi Tanabe, Masaaki Yamada
Quantum Physics
Beyond Legal Spacing: A Residual-Aware Characterization of Entangling-Zone Spacing in Neutral-Atom Compilation
Xinyi Li, Yifeng Peng and Ying Wang
Neutral-atom processors rely on spatially arranged
qubit arrays and parallel Rydberg entangling gates for scalable execution. Their compilers enforce
geometric spacing rules for simultaneous gates, yet legal separation does not make residual van der Waals coupling disappear. This paper studies that gap between
geometric legality and residual noise by treating entangling-zone spacing as a cross-layer reliability-parallelism variable anchored to experimental neutral-atom geometry. We combine fixed-schedule residual replay, surface-code simulation with matched correlated decoding, and fresh recompilation to connect spacing to physical residual exposure, logical reliability, and makespan cost. The results show that near-floor spacing can produce structured correlated exposure that is visible both at the physical layer and, in the tightest case, after
quantum error correction (QEC). Modest
geometric slack strongly suppresses this residual contribution, but the timing cost of looser spacing is mediated by placement and scheduling rather than by a simple monotonic slowdown. These findings distinguish hardware legality from residual-noise safety and motivate spacing-aware compiler evaluations that report physical geometry, QEC absorption, and scheduling cost together.
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Lattice Field Theory · Cross-listed from eess.SP
Finite-range Lattice Momentum Operators for Quantum Field Theory
Jan C Olivier and Etienne Barnard
We propose a Z-transform framework for the analysis and synthesis of finite range
lattice momentum operators in
quantum field theory. In this formulation, translation-invariant
lattice operators are represented as functions of the complex variable $z$ in the unit circle, allowing their spectral properties to be analyzed using tools from digital signal processing and rational approximation theory. Within this framework, the
fermion doubling problem is reinterpreted as the appearance of unwanted zeros of the discrete momentum operator on the unit circle — an aliasing phenomenon in the sense of the Nyquist sampling
theorem — and the conditions for ghost suppression are expressed as precise constraints on the zero structure of the operator's transfer function. It is proven that no rational function can satisfy all required conditions simultaneously, motivating the finite impulse response approach developed here. This reframing naturally suggests a class of finite-range momentum operators, constructed by solving a least-squares approximation problem in the frequency domain. The resulting finite impulse response (FIR) operator approximates the continuum derivative across the full Brillouin zone, with ghost suppression achieved through the accuracy of the spectral approximation rather than through the addition of a
symmetry-breaking Wilson term or the infinite-range nonlocal SLAC derivative. Numerical investigation confirms that near $\theta = \pi$ only plane waves propagate coherently, and these exhibit group velocities far exceeding the speed of light, further distinguishing them from physical low-energy excitations. No ghost wave packet solutions exist near $\theta = \pi$.
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Quantum Physics
Reduced State Stabilizer Rényi Entropy as a Probe of Quantum Phase Transitions in Frustrated J_1-J_2 Spin Models
George Biswas, Santanu Sarkar, Jun-Yi Wu et al. (+1 more)
We investigate whether the second-order purity-corrected stabilizer Rényi
entropy (SRE) of reduced two-
qubit density
matrices can serve as a reliable local indicator of
quantum phase transitions (QPTs) in frustrated
quantum spin systems. We consider the one-dimensional isotropic \(J_1-J_2\) Heisenberg model, the one-dimensional XXZ \(J_1-J_2\) model, and the two-dimensional \(J_1-J_2\) Heisenberg model on a \(4\times4\) square
lattice. Unlike several previously studied
quantum information measures, which fail to detect QPTs in the ground state of these frustrated systems, the reduced ground-state purity-corrected SRE successfully identifies most transitions. For the remaining cases, we consider a low temperature subjacent state, modeled as a statistical mixture of the ground and first excited states with a Maxwell–Boltzmann-type occupation probability. For the 1D isotropic model, the subjacent-state SRE shows a discontinuity at the critical point, yielding \(\alpha_c(\infty)=0.24116\), in excellent agreement with established values; the ground-state SRE shows a point of inflection, yielding \(\alpha_c(\infty)=0.2681\). For the 1D XXZ model, the subjacent-state SRE reproduces the full anisotropy dependent phase diagram, while the ground-state SRE captures transitions only at low anisotropy. For the 2D model, the subjacent-state SRE detects two transitions, at \(\alpha_c(4\times4)=0.40781\) and \(0.6208\), while the ground-state SRE identifies the second at \(0.6230\). Compared with conventional two-
qubit entanglement, purity-corrected SRE shows a clear advantage in revealing otherwise-invisible phase transitions, establishing it as a robust, efficient, local probe of frustrated
quantum criticality.
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All authors George Biswas, Santanu Sarkar, Jun-Yi Wu, Anindya Biswas
Physics and Society
Reputation and institutional certification as complementary trust mechanisms in a single online market
Yuta Kido and Yohsuke Ohtsubo
Reputation and institutional certification are the two main trust mechanisms under information asymmetry, yet their interaction remains poorly understood. Here we analyze nearly one million eBay listings of Pokemon trading cards. Each listing pairs the seller's reputation with their signal choice, that is, whether they used costly third-party certification, their own costless claim (self-grading), or neither to convey the card's quality. First, we find that certification and self-grading partition the
market. Self-grading prevails where reputation is high and value low, whereas certification prevails in the
market's opposite corner. Furthermore, seller reputation raises the price premium of self-grading but not of certification. We then show that both empirical patterns follow from a signaling model in which false self-grading damages reputation, whereas certification requires an up-front fee. These results suggest that, even within a single
market, trust rests not on a choice between reputation and institutions but on a division of labor.
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High Energy Physics (Phenomenology)
Lepton flavor violating decays $l_j \rightarrow l_i\gamma$ in the $U(1)_X$VLFM
Shuang Di, Wei-Hang Zhang, Zi-Xuan Su et al. (+3 more)
In the $U(1)_X$ vector-like
fermion model ($U(1)_X$VLFM), the Standard Model(SM) gauge group is extended with an additional $U(1)_X$
symmetry. Vector-like
fermions and right-handed
neutrinos are introduced, providing new sources of
lepton flavor violation(LFV). In this paper, we perform a detailed study of the LFV decays $l_j \to l_i \gamma$ (with $j = \tau, \mu$; $i = \mu, e$; $i \neq j$) in this model. The numerical results show that, in certain parameter regions, the branching ratios of these processes can become large enough to be probed in future experiments. This work provides important theoretical guidance and constraints for exploring new physics beyond the SM.
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All authors Shuang Di, Wei-Hang Zhang, Zi-Xuan Su, Guo-Zhu Ning, Xing-Xing Dong, Shu-Min Zhao
Statistical Mechanics
Spontaneous symmetry-breaking in equilibrium tree-packing configurations of a kinetically constrained cubic-lattice system
Hai-Jun Zhou
We explore kinetic-constraint induced thermodynamic phase transition in the cubic
lattice, employing the Fredrikson-Anderson
spin model with hyperparameter $K=2$ as a representative kinetic system. Each
lattice site may flip its binary occupation state if at most one of its six nearest neighbors is currently occupied. The whole set of microscopic configurations that are kinetically connected with the fully empty one is described by an
equilibrium partition function with a single global constraint, that is, the occupied sites do not form closed loops but instead organize into different tree components in the
lattice. We discover a continuous thermodynamic gas–
crystal phase transition in the cubic system and determine the critical chemical potential $\mu^* \approx -3.252$, at which the occupied sites of the
equilibrium tree-packing configurations start to prefer one of the two nested cubic sublattices. This thermodynamic phase transition is absent in the two-dimensional square
lattice.
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Strongly Correlated Electrons
Second Harmonic Generation Spectroscopy of the Surface Charge Density Wave in the Weyl Semimetal CoSi
Awadhesh K. Das, Wesley E. Deeg, Sujan Subedi et al. (+3 more)
Using temperature-dependent rotational anisotropy second harmonic generation (RA-SHG), we identify a charge density wave (CDW) instability on the CoSi (001) face with an onset temperature at $90.0 \pm 0.8$ K. The SHG response tracks the order parameter amplitude, dominated by two nonlinear tensor elements, whose background-subtracted intensity evolves with temperature as a power law. The extracted critical exponent $\beta = 0.30 \pm 0.03$ is consistent with the 3D XY universality class, an unexpected result for a nominally two-dimensional surface layer. No corresponding anomaly is observed in the bulk response, establishing the transition as a purely surface-driven phase transition. We attribute this unexpected scaling to the coupling between surface
Fermi-arc states and the bulk
topology they are tied to, grounded in a previously observed intra-unit-
cell phase relationship between surface sublayers that gives the order parameter intrinsic three-dimensional structure.
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All authors Awadhesh K. Das, Wesley E. Deeg, Sujan Subedi, Chandra Shekhar, Claudia Felser, Darius H. Torchinsky
High Energy Astrophysical Phenomena
Sudden emergence of a low-frequency hard X-ray lag in the Seyfert 1 galaxy Mrk 1044
Jia-Lai Kang and Jun-Xian Wang
Hard X-ray lags, where low frequency variations in the hard X-ray band lag behind those in the soft band, have been detected in many active
galactic nuclei (AGNs) and are generally attributed to the inward propagation of
accretion-flow fluctuations through an extended corona. In a long XMM-Newton observation of the Seyfert 1
galaxy Mrk 1044, we found a remarkable transition in the lag behavior within a single exposure, while the X-ray flux and spectral shape remained largely unchanged. During the first 60 ks, no significant hard X-ray lag was detected, whereas in the subsequent 60 ks, a pronounced lag emerged. The lag was so prominent that a large-amplitude flux variation event during the lag-detected interval, characterized by a gradual dimming followed by recovery, produced a remarkable clockwise loop in the flux-softness diagram. The sudden appearance of the hard X-ray lag suggests that the X-ray corona underwent a rapid transition from a compact to an extended configuration. This scenario is further supported by two independent observational signatures: (1) the variability became noticeably smoother, with a redder power spectral density (PSD), during the lag-detected interval, and (2) the broad Fe K$\alpha$ line profile became narrower and the reflection continuum weaker. These findings highlight the diagnostic power of tracking rapid changes in hard X-ray lags for probing the physical structure and
evolution of AGN coronae, and demonstrate that identifying prominent loops in the flux-softness diagram provides an effective way to locate intervals with significant hard X-ray lags.
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Fluid Dynamics
Noise-separated evidence for a slow collective displacement in a rarefied hypersonic bow-shock layer
Ahmad Shoja-sani and Ehsan Roohi
Time-resolved direct simulation Monte Carlo (DSMC) fields are used to test whether a detached rarefied hypersonic bow shock contains a slow collective displacement that can be separated from correlated particle-sampling fluctuations. Mach-10 rotationally relaxing nitrogen flow over a circular cylinder is analysed for diameter-based Knudsen number $0.01\leq \KnD\leq1$, where $\KnD=\lambda_\infty/D$, $\lambda_\infty$ is the freestream mean free path and $D$ is the cylinder diameter. A density half-jump front is extracted on body-normal rays, unsupported solid-side points are excluded, and temporal coarse graining is performed before feature extraction. Persistent and sampling covariance components are compared using a penalized composite-fit score, design-scale cross-validation, block resampling, synthetic controls and complementary full-field matched filters. Corrected field proper orthogonal decomposition (POD) is high rank at every Knudsen number, yet a weak, same-signed angular displacement is resolved at $\KnD=0.01$ and $0.025$. Independent random-seed and simulator-particle-loading repeats recover the angular shape and relaxation time while the raw sampling variance changes with loading. Across the two resolved states the mean density layer broadens by $82\%$, while the angular shapes remain strongly aligned. Density and pressure recover the marker motion most strongly; the reduced Mach-number and translational-temperature participation at $\KnD=0.025$ is evidence consistent with moment-selective weakening, although observable-dependent signal-to-noise remains a possible contributor. The signal is interpreted as a low-pass bow-layer response embedded in broadband kinetic fluctuations, not as a newly discovered discrete oscillation or a demonstrated linear instability. The higher-Knudsen records are not sufficiently sensitive to establish physical disappearance.
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Quantum Physics
A Connectivity-Order Law and Conditional Minimal-Mechanism Identification in Many-Body Geometric Phases
Kuo Hai, Junhao Huang, Qiong Chen et al. (+1 more)
The value of a multiqubit
geometric phase at a single operating point does not reveal whether it was generated directly or through a connected sequence of lower-body interactions. For analytic, gapped, nondegenerate Abelian holonomies, we jointly resolve logical support and independently calibrated coupling support. Every nonzero connected response must involve an active set that connects and covers the target and must contain one factor of each active coupling, yielding the sharp onset bound $\nu_S \geq \tau_E(S)$. The same selection law applies locally to projected Berry
curvature. Conversely, an unrestricted finite-dimensional construction realizes all responses allowed by the connected-cover condition simultaneously, making the condition necessary and sufficient within this
theorem class. Operationally, simultaneous confidence bands certify detected mixed responses while controlling false positives; a factor-of-two separation condition additionally recovers exact library-relative response minima. In a complete dictionary, nontriviality of every minimal-cover response is generically necessary and sufficient for these minima to coincide with the minimal calibrated mechanisms. Three-
qubit Wilson calculations distinguish direct and pair-mediated routes with the same endpoint phase, and a synthetic Ramsey audit locates the finite-resolution boundary.
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All authors Kuo Hai, Junhao Huang, Qiong Chen, Wenhua Hai
Optics
Nanophotonic dispersion engineering in tantala-based microresonators with ultralow-loss claddings
Alexa R. Carollo, Atasi Dan, Jizhao Zang et al. (+3 more)
Integrated photonics optimized to leverage low loss, nonlinear-optical processes and optoelectronic integration requires robust optical cladding materials and associated fabrication process flows. We develop low-loss silicon dioxide (SiO$_2$) claddings with tantalum pentoxide (Ta$_2$O$_5$, tantala) integrated photonics to realize robust, high intrinsic quality factor ($Q_i$) microresonators and photonic-
crystal resonators (PhCRs) for
soliton microcomb generation. Specifically, we introduce a full-wafer, low-temperature process compatible with two tantala-based films: pure tantala and an amorphous metal-
oxide mixture of titanium dioxide (TiO$_2$, titania) and tantala. Combining tantala with titania enhances the film's resistance to damage from the SiO$_2$ cladding deposition process, offering access to high $Q_i$ above $4 \times 10^6$ in fully cladded microresonators. Our platform supports low-loss edge couplers, group-velocity dispersion engineering by waveguide geometry, access to nanophotonic structures particularly to control phase-matching, and high dimensional tolerance in devices across an entire wafer. Using the platform, we explore the generation of high-efficiency, dark-
soliton microcombs with repetition frequency from 50 GHz to 500 GHz, which supports applications such as photonic artificial intelligence acceleration, electronic signaling, and optical data communication.
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All authors Alexa R. Carollo, Atasi Dan, Jizhao Zang, Haixin Liu, Nitesh Chauhan, Scott B. Papp
Instrumentation and Detectors
Scintillation Properties of a Stilbene Crystal for Low-Mass Dark Matter Searches
Se Hwan Lee, Jaeyoung Cho, D. Joseph Daniel et al. (+4 more)
Direct searches for low-mass WIMPs require sensitivity to low-energy
nuclear recoils. Hydrogen-containing targets offer favorable scattering kinematics because low-mass WIMPs can transfer a larger fraction of their kinetic energy to hydrogen
nuclei than to heavier
nuclei. Trans-stilbene (t-stilbene) is a hydrogen-rich organic
crystal that combines this kinematic advantage with efficient scintillation and pulse-shape discrimination (PSD).In this work, we characterize the scintillation decay behavior and effective light yield of a solution-grown t-stilbene
crystal to evaluate its suitability for dark matter detection. The detector consists of a cylindrical
crystal approximately 1.1 cm in diameter and 1.1 cm in length, optically coupled at opposite ends to two Hamamatsu R12669 photomultiplier tubes. The scintillation waveforms are described by a triple-exponential decay model, yielding fraction-weighted decay time constants of $8.3 \pm 0.2$ ns (fast), $20.1 \pm 0.3$ ns (medium), and $74.2 \pm 1.1$ ns (slow). The effective light yield, determined using a 59.54 keV $\gamma$ ray from an $^{241}$Am source, is $3.37 \pm 0.02$ photoelectrons per keV.These measurements establish the baseline performance of the detector and support further evaluation of t-stilbene as a target material for rare-event and low-mass dark matter searches.
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All authors Se Hwan Lee, Jaeyoung Cho, D. Joseph Daniel, Hongjoo Kim, Young Ju Ko, Jungho So, In Soo Lee
Quantum Physics
Weak Typicality of von Neumann Entanglement Entropy in Gaussian Boson Sampling
Hongru Zhao
We study the von Neumann
entanglement entropy generated by a Haar distributed passive interferometer acting on $n$ equally squeezed input modes with fixed nonzero squeezing strength $s$. Previous work established proportional weak typicality for integer R'enyi orders $\alpha\geq 2$ and stated a sublinear von Neumann result, while the proportional von Neumann case remained open. For a subsystem of $k_n$ modes satisfying $k_n/n\to r\in(0,1)$, we prove that, for every $\varepsilon>0$ and all sufficiently large $n$, $\mathbb{P}\left(\left|\frac{S_{1,n}}{\mathbb{E}S_{1,n}}-1\right|\geq\varepsilon\right)\leq2\exp\left[-\frac{c_{s,r}\varepsilon^2n^2}{\log^2(en)}\right].$ The proof represents the
entropy as a singular value statistic of a principal block of $UU^{\mathsf T}$, where $U$ denotes the
unitary interferometer. It regularizes the logarithmic singularity at the endpoint corresponding to a pure Gaussian mode and applies concentration on the
unitary group. The result establishes proportional von Neumann weak typicality and further implies almost sure convergence of $S_{1,n}/\mathbb{E}S_{1,n}$ to $1$, a typical volume law, and the variance bound $\mathrm{Var}(S_{1,n})=O_s(\log^2 n)$. An accompanying Lean 4 development verifies the proof chain.
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