Soft Condensed Matter · Cross-listed from cs.LG
Physics-Constrained Neural Surrogate for Domain Growth Prediction in Systems with Conserved Kinetics
Vijay Yadav, Pallvi Pandey, Madhu Priya et al. (+2 more)
The spatiotemporal
evolution of many physical, chemical, and biological systems is described by nonlinear partial differential equations (PDEs). Recently, deep neural network-based surrogate models have emerged as efficient alternatives to computationally expensive numerical PDE solvers. In this work, we propose a physics-constrained deep neural network as a surrogate model to learn the microstructural
evolution of a binary mixture, in which conservation of the order parameter is imposed directly on the network output as a hard constraint. We train the model to accurately predict the time-
evolution of phase separation in binary mixtures governed by the Cahn-Hilliard equation. We show that predictions from our trained surrogate model remain stable and accurate over long-time rollouts for both critical and off-critical mixtures and preserve the mixture composition throughout
evolution. In contrast, a variant in which conservation is enforced only via a penalty term in the loss function drifts away from the initial composition and significantly loses predictive accuracy over the same rollout. This establishes that the hard constraint is essential for long-time stability and order parameter conservation. We also show that our model accurately captures the growth of domain size and is consistent with the Lifshitz-Slyozov domain-growth law. These results demonstrate the effectiveness of the proposed framework for modeling systems with conserved kinetics, and the construction extends directly to other systems with conserved quantities.
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All authors Vijay Yadav, Pallvi Pandey, Madhu Priya, Manish Dev Shrimali, Prabhat K. Jaiswal
Computational Physics · Cross-listed from eess.SP
FEM-Based Dispersion and Mode Analysis of Rectangular, Circular, and Ridge Waveguide Geometries
Sabrina Saima
This paper presents a two-dimensional finite element method (FEM) solver for computing modal field distributions and dispersion characteristics of hollow metallic waveguides. To solve the waveguide problem, the source-free frequency-domain Maxwell equations are reduced to scalar Helmholtz
eigenvalue formulations evaluated over the waveguide's transverse cross section. The computational method determines both transverse electric (TE) and transverse
magnetic (TM) mode families by enforcing perfectly electrically conducting (PEC) boundary conditions. The framework is initially validated against analytical
benchmarks using empty rectangular and circular waveguides, demonstrating high accuracy in computing cutoff wavenumbers, dispersion curves, and field maps for the first three unique modes. After validation, the solver is applied to analyze single-ridged and double-ridged waveguides. The numerical results demonstrate that introducing metallic ridges successfully redistributes the modal fields and significantly lowers the cutoff frequency of the dominant mode relative to empty rectangular guides. Ultimately, this work confirms that the generalized
eigenvalue FEM formulation is a robust and adaptable tool for analyzing complex waveguide geometries where exact analytical solutions are unavailable.
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Lattice Field Theory
Reflection-Positive Construction of a Four-Dimensional SU(N) Yang-Mills Theory with Mass Gap and Confinement
Mir Faizal and Arshid Shabir
In the Euclidean view one must first require that positivity not be violated, and from this modest demand, together with locality, a great deal follows: starting from a reflection-positive
lattice formulation of pure SU(N) Yang-Mills theory we obtain a transfer operator with a uniform gap, while large Wilson loops already show an area law by means of convergent character (
polymer) expansions; a finite-range, gauge-covariant multiscale analysis then carries these features from one scale to the next with interlaced inequalities whose small defects can be summed, so that exponential clustering and a strictly positive string tension endure in the continuum; the Osterwalder-Schrader reconstruction turns these Euclidean facts into a Minkowski theory with a self-adjoint
Hamiltonian, the spectral gap lying above the
vacuum and the linear potential for static charges appearing, which gives a concrete picture of confinement; the construction depends on no special regulator, for a single-scale Lipschitz control and a telescoping argument bind all admissible reflection-positive slicings into a unique limiting measure and thus secure universality; moreover, the same framework admits entry from weak coupling, so that the continuum reached from strong coupling meets the one approached along an asymptotically free trajectory, yielding one and the same theory; in my view this is how mathematical clarity and physical insight cooperate: positivity, locality, and renormalization working together so that the mass gap and confinement are not marvels to be assumed, but natural properties of the non-Abelian
vacuum.
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General Physics
Cosmic adiabatic photon creation: Temperature law and blackbody spectrum
J.A.S. Lima, S.R.G. Trevisani and R.C. Santos
The temperature-
redshift relation (
cosmic thermometer) is rediscussed in the framework of gravitationally induced
photon production in the expanding universe. It is found that the same extended temperature law can be derived based on three independent methods, namely: (i) through a simple heuristic approach, (ii) based on macroscopic irreversible thermodynamics with
photon creation, and (iii) using a kinetic relativistic Boltzmann equation incorporating gravitational
photon creation. All these methods yield the same answer. The modified kinetic treatment reveals not only that the Planckian blackbody spectrum endowed with the adiabatic creation is preserved in the course of the expansion but also that CMB anisotropies and distortions can be treated properly. The new
cosmic thermometer suggests a crucial test to the standard
cosmic concordance model in the thermal sector. It is also argued that the present results may open a new route for scrutinising the H0
Supernovae-CMB tension challenging the LambdaCDM model.
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Soft Condensed Matter
Kinetics of coagulation phenomena from a granular matter perspective
Gustavo Castillo and Nicolás Mujica
Aggregation processes play a central role in systems ranging from aerosol coagulation and cloud formation to
dust growth in protoplanetary disks and granular materials. These processes are traditionally described by Smoluchowski's coagulation equation, which provides a mean-field account of growth through binary collisions. However, incorporation of granular physics-dissipative interactions, spatial heterogeneity, and force transmission through contact networks-reveals important limitations of this framework. In this review, we show how such effects lead to the breakdown of mean-field assumptions and motivate a view of aggregation as a multi-scale process shaped by the interplay between interactions, structure, and collective dynamics. Phenomena such as segregation, jamming, and clogging further highlight the role of mechanical constraints and spatial organization in limiting or redirecting growth. By integrating insights from granular physics, aerosol science, and astrophysics, we outline a unified perspective on coagulation in non-
equilibrium particulate systems. This paper is part of the thematic issue "Sand, silos and asteroids: clustering challenges in granular materials research".
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General Relativity and Quantum Cosmology
Black Hole Radiation Sparsity and Bekenstein Entropy Loss in Non-Commutative Schwarzschild Spacetime
Abdellah Touati
In this paper, we investigate the sparsity of black hole radiation, the Bekenstein
entropy loss, and the total particle emission of a Schwarzschild black hole (SBH) within the framework of non-commutative (NC) gauge theory of
gravity. First, we provide a brief review of black hole (BH) thermodynamics, computing both the deformed Hawking temperature and
entropy. In this geometry, the divergent behavior of the temperature is removed, and a logarithmic correction to the
entropy emerges. We then present the NC corrections to the Bekenstein
entropy loss of the SBH alongside the total number of emitted particles. Our results show that the total number of emitted particles is proportional to the
entropy behavior of the NC SBH, which is consistent with non-thermal radiation. Finally, we analyze the sparsity of Hawking radiation in this geometry, finding that the NC SBH exhibits extremely sparse radiation ($\hat{\eta} \gg 1$), which diverges at the final stage of evaporation as the black hole ceases to radiate.
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Instrumentation and Detectors
Experimental updates on development of accelerator-driven ion source at TRIUMF to benchmark Ba-tagging techniques for future neutrinoless double beta decay searches
D. Ray, M. Marquis, A.V. Balbuena et al. (+4 more)
Neutrinoless double beta decay ($0\nu\beta\beta$) could provide a way to probe physics beyond the Standard Model of particle physics. The proposed nEXO experiment aims to search for $0\nu\beta\beta$ in $^{136}$Xe using a tonne-scale
liquid xenon (LXe) time projection chamber. The projected half-life sensitivity for nEXO for 10 years of livetime is $>$10$^{28}$ years. Efforts are ongoing to further suppress backgrounds and increase the experiment's sensitivity. One approach pursued is Ba-tagging, which entails extracting and identifying the daughter nuclide from the $\beta\beta$-decay of $^{136}$Xe, $^{136}$Ba. Once successful, this technique has the potential to separate background events from true $\beta\beta$ events. While different extraction and identification methods are being investigated by different groups, a Ba-ion source is required for testing, quantifying and optimizing them. An accelerator-driven ion source is currently being developed at TRIUMF, where radioactive ions will be be injected into and stopped in an LXe volume, collected electrostatically and detected using $\gamma$ spectroscopy. In this contribution, an experimental status update on the commissioning of this Ba-ion source at TRIUMF is provided.
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All authors D. Ray, M. Marquis, A.V. Balbuena, T. Brunner, T. Daniels, A.A. Kwiatkowski, A. Lennarz
Quantum Physics
Theoretical Study for Generating Optical GKP State via a Single-Photon-Added Squeezed Vacuum
Deriyan Senjaya
A theoretical framework is developed to analyze the generation of the optical GKP state using a single-
photon-added squeezed
vacuum. This state, defined by the squeezing parameter $r$, is injected into a 50:50 beam splitter, and the optical GKP state is obtained through conditional measurement at one output port. The single-
photon-added squeezed
vacuum is especially prominent in this context because it provides a simpler and more experimentally accessible ingredient than Schrodinger cat states, while conditional measurement ensures projection onto a state that closely approximates the finite-energy GKP form. Fidelity is employed to quantify this closeness, and the analysis demonstrates that the scheme achieves a maximum fidelity of 85% at a squeezing level of $3.76 \ \text{dB}$. This performance surpasses approaches based on squeezed optical odd Schrodinger cat states, underscoring the single-
photon-added squeezed
vacuum as a practical and effective pathway toward fault-tolerant photonic
quantum computing.
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Physics and Society
A systematic review of COVID-19 epidemic models with endogenous human behaviour. What's next?
Elena D'Agnese, Alessia Melegaro, Vittoria Offeddu et al. (+4 more)
Human behaviour and epidemic dynamics are intertwined, yet accounting for this feedback remains one of the key challenges of epidemiological modelling. The COVID-19 pandemic was an opportunity to overcome the traditional limitations of the field, raising expectations that data-informed endogenous approaches to behaviour modelling would advance substantially. To quantify the progresses made, we conducted a systematic review of SARS-CoV-2 transmission models endogenously including human behaviour in response to epidemic dynamics. The COVID-19 pandemic saw great strides in terms of the expanded use of empirical data in epi-behavioural modelling. However, it also showed shortcomings with respect to limited use of behavioural empirical data, lack of innovation in model structure, and limited engagement with other disciplines and decision-makers. Overall, our results suggest that identifying priorities in model design and behavioural data, building an adequate data collection infrastructure, leveraging on AI advancements, and fostering interdisciplinarity are strategies of utmost importance for pandemic preparedness.
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All authors Elena D'Agnese, Alessia Melegaro, Vittoria Offeddu, Alberto d'Onofrio, Nicola Perra, Chris T. Bauch, Piero Manfredi
General Physics
Kinematic Probes of Type-II MMG: Padé Cosmographic Analysis of VCDM
Soumya Kanta Bhoi, Sai Swagat Mishra and P.K. Sahoo
We study the late-time expansion history of the Universe within the VCDM model, a Type-II MMG realization that preserves the successes of General Relativity while extending beyond constant
vacuum energy through a minimal
Hamiltonian modification, generating a time-dependent
vacuum sector without introducing additional degrees of freedom. We investigate this framework within a cosmographic approach by employing a Padé $P_{(2,1)}$ approximation for the Hubble parameter and luminosity distance, allowing the cosmographic parameters to be expressed directly in terms of the underlying VCDM model parameters and enabling a data-driven reconstruction of the expansion history. The model is constrained within a
Bayesian framework using the MCMC technique, implemented via the affine-invariant ensemble sampler, with a joint analysis of
cosmic chronometers, DESI BAO, and Type Ia
supernova datasets (Union3, Pantheon+, and DESY5). We find that the model parameters are tightly constrained and consistent across different
dataset combinations, with the jerk parameter remaining very close to its $\Lambda$CDM value, $j_0 \simeq 1$, indicating no significant deviation at the level of higher-order cosmography. Furthermore, the transition feature previously reported in VCDM is not observed within the Padé $P_{(2,1)}$ cosmographic reconstruction, suggesting that it is not a robust requirement of current observational data but is sensitive to the choice of parametrization. Overall, our results indicate that the VCDM model effectively mimics $\Lambda$CDM at the background level when constrained through a cosmographic approach, underscoring the importance of model-independent reconstructions in assessing alternative cosmological scenarios.
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Mathematical Physics
Thermodynamic coefficients in third-order relativistic fluid dynamics
Teboho Abram Moloi and Azwinndini Muronga
We developed the third-order hydrodynamic equations using relativistic extended thermodynamics of gases with 14 independent fields. The resulting fluid equations are based on the relativity principle, the
entropy principle, and the requirement of
hyperbolic, and hence finite, propagation of disturbances, which is automatically incorporated. The expressions of
entropy, four-current, shear-stress tensor, dynamic pressure, and heat flux are expanded up to third order (cubic). We explicitly present the newly calculated coefficients in the
equilibrium properties of an ultra-relativistic gas regime and the non-degenerate relativistic gas. Contrary to the general cases, the non-degenerate regime eliminates fugacity from the coefficients, allowing for the easy normalization of these coefficients, and the ultra-relativistic regime provides us with the upper bounds of these coefficients. We found good agreement on some of the coefficients as compared to calculations from earlier models, specifically in kinetic theory, and other coefficients had slightly different values to those obtained in kinetic theory.
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High Energy Physics (Phenomenology)
Probing TeV-Scale Inverse-Seesaw Leptogenesis and Majorana Dark Matter in $U(1)_{B-L}$ Models at Multi-TeV Muon Colliders
Xin-Qiang Li, Himadri Roy, Tripurari Srivastava et al. (+2 more)
We investigate a predictive and testable framework in which dark matter (DM), heavy-
neutrino dynamics, and the BAU originate from correlated interactions within a local $U(1)_{B-L}$ extension of the SM. Unlike conventional $B-L$ constructions based on the type-I seesaw, we employ an inverse-seesaw mechanism realized through a sterile
fermion $S_{1}$ and a complex scalar field $\phi$, whose
vacuum expectation value simultaneously generates the masses of the heavy
neutrinos $N_{1,2}$ and the Majorana DM
fermion $\chi$ via Yukawa couplings. The small
lepton-number-violating parameter induced by a higher-dimensional operator leads to naturally light active
neutrinos together with TeV-scale heavy
neutrinos and sizable active-sterile mixing, yielding distinctive
collider signatures unavailable in minimal $B-L$ models. The relic abundance of $\chi$ is governed by annihilation channels mediated by the same scalar and gauge interactions, producing a direct and model-specific correlation between successful leptogenesis and the observed DM relic density. A combined parameter-space analysis incorporating
neutrino oscillation data,
lepton-
flavor-violating processes, direct-detection limits, and
collider bounds on $N_{1,2}$ and $Z^\prime$ reveals a narrow yet robust region consistent with all these constraints. Representative
benchmark points in this region are examined at a future multi-TeV
muon collider. Heavy-
neutrino production through electroweak processes yields striking signatures in the dilepton plus missing energy ($2\ell + E\!\!\!/_T$) and single-
lepton plus di-jet plus missing energy ($1\ell + 2j + E\!\!\!/_T$) final states. These channels demonstrate that next-generation
muon colliders offer a powerful and complementary probe of the inverse-seesaw origin of
neutrino masses, the DM relic density, and the TeV-scale leptogenesis within such an extended $U(1)_{B-L}$ framework.
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All authors Xin-Qiang Li, Himadri Roy, Tripurari Srivastava, Ya-Dong Yang, Xing-Bo Yuan
Quantum Physics
Single Photon Cross-Phase Shifts Can Be Enhanced by Localization in both Frequency and Time
Xinyu Jiao, Vida-Michelle Nixon, Kyle Thompson et al. (+1 more)
Single-
photon optical nonlinearities face a fundamental trade-off: maximum nonlinearity requires both spectral resonance (narrow bandwidth) and high peak intensity (short duration), constraints that are incompatible due to the time-energy uncertainty relation. We demonstrate experimentally that this limitation does not need to exist in cases involving post-selection. We measure a cross-phase shift (XPS) produced by a resonant
photon from a narrow-band source that is first transmitted through a cold atomic cloud and then localized in time through detection. The peak size of this XPS is greatly enhanced compared to that of Gaussian single-
photon-level pulses without post-selection, benefiting from the narrow bandwidth of the resonant prepared state and the high intensity of the post-selected state simultaneously. We measure enhancements in the peak XPS of 6$\pm$1 at an optical depth (OD) of 2.4$\pm$0.1, and our results are in qualitative agreement across a range of optical depths with the recently developed weak value theory of atomic excitation [Thompson et al., APL
Quantum 2, 036108 (2025)] for such post-selected
photons. This work uncovers new consequences of having simultaneous knowledge of frequency and time, raising new foundational questions about how a particle behaves, and interacts with other systems, when its preparation and post-selection are non-commuting.
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All authors Xinyu Jiao, Vida-Michelle Nixon, Kyle Thompson, Aephraim Steinberg
Instrumentation and Methods for Astrophysics
Revealing Cosmic Ecosystems with the Hubble Space Telescope in 2030s and Beyond
Sanchayeeta Borthakur, Tanmay Singh, David French et al. (+22 more)
Ultraviolet spectroscopy with the Hubble Space
Telescope (HST) provides the most direct and sensitive probe of the disk-circumgalactic medium (CGM) interface at radii of 20 kpc, where
galaxies exchange gas, metals, and energy with their surroundings. Many of the key diagnostics of the multiphase circumgalactic medium – including H I, O VI, C II-IV, Si II-IV, N V, Ne VIII, and other metal transitions – lie in the ultraviolet and are inaccessible from the ground, making HST the only observatory capable of making the required observations. By measuring the physical (column density, density), chemical (
metallicity, ionization structure), and kinematical properties of the gas at the disk-CGM interface, UV absorption-line spectroscopy reveals how
galaxies acquire fresh fuel, recycle enriched material, and drive feedback into their
halos. When combined with spectroscopic characterization of the host
galaxy's
stellar populations and the feedback they generate (
outflow velocity, mass loading), we will establish a direct understanding of how
stellar populations enable circulation of gas and metals through the
galactic ecosystem. HST's ultraviolet (UV) spectroscopic capability provides the only comprehensive observational pathways for uncovering the physical drivers that regulate
galaxy growth and
evolution in the low-
redshift Universe.
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All authors Sanchayeeta Borthakur, Tanmay Singh, David French, Yakov Faerman, Kate Rubin, Brad Koplitz, Rongmon Bordoloi, Frances H. Cashman, Matthew J. Hayes, Yong Zheng, Joseph N. Burchett, Jane C. Charlton, Hsiao-Wen Chen, Andrew J. Fox, Yucheng Guo, Timothy M. Heckman, Christopher J. Howk, Sean D. Johnson, Glenn G. Kacprzak, Varsha P. Kulkarni, Nicolas Lehner, Sowgat Muzahid, Namrata Roy, Evan Scannapieco, Jessica K. Werk
General Relativity and Quantum Cosmology
Statistical-Uncertainty-Driven Selection of Evaluation Frequency for Time-Dependent Sensing Calibration: A Demonstration with KAGRA Data
Shingo Hido, Takahiro Yamamoto, Dan Chen et al. (+2 more)
Accurate calibration of the gravitational-wave strain h(t) is essential for both detection and astrophysical inference. In operating detectors, slow temporal variations in the sensing response are tracked using calibration lines, but practical constraints can prevent those lines from being injected at frequencies that are favorable for precise estimation of sensing-side parameters. We present a statistical framework for preselecting evaluation frequencies under such constraints. We apply this framework to KAGRA data from the first part of the fourth LIGO-Virgo-KAGRA Observing Run, for which the nominal cavity-pole frequency was about 18 Hz, while the sensing-side calibration line used in practice was injected at 32.7 Hz. For each candidate evaluation frequency, we construct the sensing function, quantify its segment-wise statistical uncertainty from empirical percentiles of the sample distribution, and rank the candidates using a score that combines the interval widths of the amplitude and phase. When a 1% amplitude interval width and a 1 degree phase interval width are weighted equally, 244 Hz is selected in all 4096 s analysis segments throughout the analyzed period. Relative to the reference frequency of 32.7 Hz, the amplitude interval width is reduced to about one quarter over a broad frequency range, while the phase interval width remains broadly comparable. We also assess the discrepancy introduced by frequency translation separately. These results suggest that the proposed method provides a useful statistical preselection framework for evaluation frequencies under practical operational constraints.
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All authors Shingo Hido, Takahiro Yamamoto, Dan Chen, Takahiro Sawada, Shinji Miyoki
Quantum Physics
Logical error estimation from syndrome data of surface-code experiments
Evangelia Takou, Cesar Benito, Arian Vezvaee et al. (+2 more)
Decoders for
quantum error correction (QEC) experiments rely on detector error models (DEMs), which encode, for each error, its probability and the detectors and logical observables it flips. Here we show that estimating DEM event probabilities from experimental syndromes is feasible, avoids independent device benchmarking, and produces useful decoder priors for estimating and reducing decoded logical error probabilities. We evaluate our methods using open-source data from surface-code
memory experiments performed on Google's Willow chip, and we carry out analogous surface-code experiments on IBM's ibm\_miami processor. Despite the different physical error scales of the Google and IBM devices, in both cases our estimated DEMs improve logical error probabilities relative to baseline device-informed DEMs, typically at the $5\%-10\%$ level and with larger gains in some IBM cases, without additional calibration
circuits, decoder fine-tuning, or supervised fitting to logical outcomes.
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All authors Evangelia Takou, Cesar Benito, Arian Vezvaee, Daniel A. Lidar, Kenneth R. Brown
Superconductivity
Superconductivity near quarter and half filling of a strongly correlated triangular Hubbard band in twisted trilayer WSe2
Yungi Jeong, Kenji Watanabe, Takashi Taniguchi et al. (+1 more)
The triangular-
lattice Hubbard model is one of the paradigmatic settings for studying correlated electronic systems with
geometric frustration that can give rise to a variety of phases. Recently, twisted
bilayer TMD systems have emerged as attractive experimental platforms for realising such a model in the moderate-correlation regime. Alternating twisted trilayer TMD systems are expected to realise stronger correlations than
bilayer systems owing to their mirror
symmetry. Here we report the discovery of superconductivity near quarter- and half-filling, together with various correlated phases, in alternating twisted trilayer WSe2 (TTWSe2). At half filling, a robust correlated insulating state persists over a broad range of displacement fields, signalling the strongly correlated regime. Upon doping, superconductivity emerges over an extended region of the phase diagram. Near quarter filling, another superconducting state appears flanked by correlated metals. Our results establish the TTWSe2 system as a compelling platform for studying strongly correlated triangular-
lattice Hubbard physics.
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All authors Yungi Jeong, Kenji Watanabe, Takashi Taniguchi, Joonho Jang
Solar and Stellar Astrophysics
Summary of the First Year of the Space Weather Around Young Suns Program: 900 Hours of Low-frequency Radio and Optical Data Dedicated to Young, Solar-type Stars
Ivey Davis, Gregg Hallinan, Nikita Kosogorov et al. (+51 more)
The Space Weather Around Young Suns (SWAYS) program was introduced in \citet{Davis2025} as a multi-wavelength monitoring program for studying the activity and particle environments of nearby, young,
solar-type
stars. The SWAYS program currently includes the Owens Valley
Radio Observatory Long Wavelength Array (OVRO-LWA) operating between 13–87\,MHz to search for
stellar equivalents of
solar type~II and III bursts, which are associated with bulk
plasma motion in the corona and interplanetary medium. These observations are accompanied by simultaneous photometric data from the high-precision, optical instrument Flarescope to identify associated
flare events. These two instruments have collectively acquired nearly 900\,hr of data with $\approx70\%$ overlap between November 2023–June 2024, dedicated to six
stars. Here, we present the results of this first season of the SWAYS observing campaign, which include a superflare from the
star EK~Draconis with no accompanying low-frequency particle-flux signal. The novelty of the coordination at these specific parts of the spectrum allow us to uniquely evaluate the conditions that may have inhibited a
radio detection. We find that the exceptionally hot, dense coronae of incredibly active
stars may not be conducive to the development of the instabilities required for type~II and III bursts, or else inspire new expectations for when we should expect to observe a signal relative to the time of the
flare. This may represent the
plasma-density complement to the magnetospheric limitations to observing space-weather signatures at low frequencies.
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All authors Ivey Davis, Gregg Hallinan, Nikita Kosogorov, Marin M. Anderson, John Baker, Judd D. Bowman, Rick Burruss, Ruby Byrne, Morgan Catha, Bin Chen, Xingyao Chen, Sherry Chhabra, Curt Corcoran, Larry D'Addario, Jayce Dowell, Katherine Elder, Dale Gary, Charlie Harnach, Carolyn Heffner, Greg Hellbourg, Jack Hickish, Rick Hobbs, David Hodge, Mark Hodges, Yuping Huang, Andrea Isella, Daniel C. Jacobs, Ghislain Kemby, John T. Klinefelter, Matthew Kolopanis, James Lamb, Casey Law, Nivedita Mahesh, Surajit Mondal, Navtej Saini, Brian O'Donnell, Kathryn Plant, Corey Posner, Travis Powell, Vinand Prayag, Andres Rizo, Andrew Romero-Wolf, Jun Shi, Greg Taylor, Jordan Trim, Mike Virgin, Akshatha K. Vydula, Sandy Weinreb, Scott White, David Woody, Sijie Yu, Thomas Zentmeyer, Peijin Zhang, Jeffry Zolkower
Nuclear Experiment
Polarized Nuclear DVCS at the EIC
Jackson R. Pybus, Xuan Li and Liliet Calero-Diaz
The Electron-Ion
Collider (EIC) will enable a series of measurements at unprecedented energies and luminosities, providing new opportunities to investigate the microscopic structure of nucleons and
nuclei at small $x_B$. Exclusive processes such as Deeply Virtual Compton Scattering (DVCS) offer unique access to the three-dimensional structure of
hadrons through Generalized Parton Distributions (GPDs), while polarized electron and ion beams further enable detailed studies of
spin-dependent structure. A model for coherent DVCS on polarized $^3$Heis developed and applied to simulations of for $9\times166$-GeV $e^3$He collisions at the EIC. Using this framework, the statistical precision achievable is estimated for measurements of beam-
spin asymmetries and for the extraction of the Compton Form Factors (CFFs) $\mathcal H_{^3\mathrm{He}}$ and $\tilde{\mathcal H}_{^3\mathrm{He}}$. Early EIC data are found to enable precise differential measurements of the unpolarized CFF $\mathcal H_{^3\mathrm{He}}$ and to provide significant constraints on its real and imaginary components. By contrast, meaningful constraints on the polarized CFF $\tilde{\mathcal H}_{^3\mathrm{He}}$ require substantially larger integrated luminosities. The kinematics of the
recoil $^3$He
nucleus are also examined, and the far-forward detector capabilities at the EIC required to tag the intact
nucleus and perform fully exclusive measurements of coherent
nuclear DVCS are discussed.
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Materials Science
Nucleation instability preempts relativistic domain wall transport in high-exchange ferrimagnetic nanowires
Pietro Diona
Current-driven domain wall motion in ferrimagnets can approach the
spin-wave velocity, giving rise to relativistic-like dynamics. While this regime has been experimentally observed in crystalline ferrimagnetic garnets and amorphous GdFeCo, the material conditions that determine whether it can be accessed remain unresolved. Here, we investigate
spin-orbit-torque-driven domain wall motion in high-exchange GdCo nanowires using magneto-optical Kerr effect microscopy. We find that nucleation preempts relativistic transport. In GdCo, no velocity saturation or high-field collapse is observed. Instead, the large exchange interaction raises the maximum
spin-wave group velocity to $\approx 7\text{--}9~\mathrm{km/s}$, far above the experimentally accessible domain wall velocities. Before this limit can be approached, increasing current density and in-plane
magnetic field induce domain nucleation, disrupting steady-state propagation. We map the boundary separating domain wall transport from nucleation instability and show that the nucleation threshold decreases with pulse duration, consistent with thermally assisted barrier crossing. These results identify nucleation as the mechanism that prevents access to the relativistic regime in high-exchange ferrimagnets and establish a dynamical phase boundary between steady propagation and nucleation.
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Chemical Physics
Elucidating the Size of Chemical Space with Assembly Theory
Juan Carlos Morales Parra, Keith Y Patarroyo, Abhishek Sharma et al. (+2 more)
Chemical space is unimaginably vast with common heuristic estimates suggesting that there are ca. 10^60 'drug-like' molecules possible below a molecular mass of 500 Da. However, these estimates largely ignore the structural and synthetic complexity of the molecules enumerated. Here we present a first-principles estimate of the size of chemical space using the Assembly Theory, which quantifies the amount of causation required to form a molecule, captured in the assembly Index. This is a measurable molecular complexity measure derived from the minimum number of recursive bond-joining operations required to construct a molecular graph. Assembly Theory partitions chemical space into levels defined by Assembly Index, allowing bounds to be placed on its growth as molecular complexity increases. We show that chemical space (the accumulated Assembly Index level sets) grows at least super-exponentially, and at most, double-exponentially with respect to the Assembly Index. Using the GDB-13 database as a reference for growth-rate estimation, we model how chemical space expands under increasing complexity and contracts under structural constraints, including atom and bond types, number of rings, ring size, and chemical motifs. Under constraints comparable to standard drug-like estimates, including molecular mass below 500 Da, our analysis yields a chemical space of approximately 10117 molecules at Assembly Index 25. Finally, we constrain chemical space by biologically relevant motifs and identify structurally relevant molecules near the accessible boundaries of these assembly-defined spaces.
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All authors Juan Carlos Morales Parra, Keith Y Patarroyo, Abhishek Sharma, David Obeh Alobo, Leroy Cronin
Quantum Physics
A Cryogenic Uniaxial Strain Cell for Quantum Devices
Bradley Lloyd, Davis Rash, Chandler Wilburn et al. (+2 more)
Mechanical strain is a powerful resource for tuning
quantum systems, but existing piezoelectric strain
cells are generally optimized for fragile, high-aspect-ratio single
crystals rather than the thick, square-profile chips typical of
semiconductor quantum devices. Furthermore, adapting these
cells for
qubits requires accommodating dense RF and DC wiring while maintaining strict electrical isolation from high-voltage piezo actuators. Here, we present a piezoelectric uniaxial strain
cell designed to homogeneously strain thick, square-profile substrates. We introduce a highly symmetric dual-chip loading configuration that effectively suppresses flexural deformation and shear stress. The
cell integrates a high-density RF/DC interposer to support standard wire bonding and encloses the actuators in a grounded Faraday cage to prevent unwanted Stark shifts in the device layer. Finite element simulations confirm that combining stiff actuators with this symmetric mounting drastically improves strain homogeneity. Finally, we validate the apparatus experimentally by applying uniaxial strain to a 200 $\mu$m thick silicon die. Surface strain measurements demonstrate an applied strain of 215 $\mu\epsilon$ for 200 V applied piezo bias.
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All authors Bradley Lloyd, Davis Rash, Chandler Wilburn, Paul Kliewer, Meenakshi Singh
Quantum Physics
Handbook of Error-Correcting Codes
Victor V. Albert and Philippe Faist
Barcode scans, clear phone calls, reliable data storage, satellite communication, and large-scale
quantum computation are all made possible by error correction. We present a handbook version of The Error Correction Zoo, a curated reference of methods for protecting classical or
quantum information from errors during storage and transmission. The handbook includes descriptions of these error-correcting codes and a classification according to the symbols they use. It also catalogues relations among codes and related objects such as sphere packings,
lattices, designs, groups, and classical and
quantum phases of matter. The collection is intended both as a rigorous reference and as a practical aid for tracing the web of code relationships and uncovering new connections.
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Other Condensed Matter
Synthetic Altermagnetism Beyond the Crystal Limit
Rodolfo A. Gallardo, Andrea M. León, Jürgen Lindner et al. (+1 more)
Altermagnetic
magnons in crystalline materials exhibit momentum-dependent splitting whose nodal structure and
chiral character are governed by the point-group
symmetry of the
magnetic sublattice rotation. Here, we demonstrate the first synthetic realization of altermagnetic magnonics in a continuum platform composed of antiferromagnetically coupled
ferromagnetic films with alternating in-plane exchange anisotropies, showing that the key signatures of altermagnetic magnonics emerge beyond the crystalline setting. Solving the linearized Landau-Lifshitz equation within a dipole-exchange framework, we show that this architecture reproduces the characteristic momentum-dependent splitting, nodal directions, and anisotropic isofrequency contours of A-type altermagnets. Long-range dipolar interactions qualitatively reconstruct this exchange-driven spectrum by lifting the nominal nodal degeneracy, hybridizing opposite-chirality modes, and producing a finite, thickness-dependent wave-vector splitting along directions that are nodal in the exchange-only limit. Extending the
bilayer to finite multilayers reveals that synthetic altermagnetism undergoes a parity-dependent reconstruction that separates surface and bulk altermagnetic excitations. These results establish altermagnetic
magnon phenomenology as an engineerable collective response of dipole-exchange multilayers beyond microscopic
crystal symmetries.
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All authors Rodolfo A. Gallardo, Andrea M. León, Jürgen Lindner, Jhon W. González
Medical Physics
A Two-Stage Framework for Fast Proton Spot Map Generation in Pencil Beam Scanning Prostate SBRT Planning
Xueyan Tang, Hok Wan Chan Tseung, Mark Pepin et al. (+6 more)
Background: In pencil beam scanning (PBS)
proton therapy, plans are delivered as
proton spot maps (PSMs). Although deep learning can rapidly predict 3D dose, direct conversion of dose into deliverable spot patterns remains limited. Purpose: We developed GenSpot, a two stage framework that infers deliverable PSMs from CT and dose, and evaluated it in prostate SBRT by comparing Monte Carlo (MC) doses from GenSpot and clinical PSMs. Methods: GenSpot uses a physics informed projected
proton spot map (PrPSM) representation, projecting spots through CT with water equivalent thickness and PDD information to align spots with the CT/dose grid while preserving linearity with spot weights. The
dataset included 1,036 fields from 259 prostate SBRT plans, split 80%/10%/10% for training, validation, and testing. A 3D SwinUNETR predicted PrPSMs from CT and dose. Field specific PSMs were reconstructed using column wise nonnegative Lasso regression with precomputed PDD curves. GenSpot and clinical MC doses were compared using MAE, 3D gamma analysis, and composite plan DVH metrics. Results: On the test set, SwinUNETR achieved PrPSM MAE of 0.06 +/- 0.02 with high similarity to clinical PrPSMs. GenSpot MC doses showed low MAE of 0.07 +/- 0.03 Gy in the nonzero dose region and gamma passing rates of 0.90 at the field level and 0.97 at plan level. Composite DVH differences were within 1 Gy for targets and organs at risk, though the CTV showed a modest high dose increase. Spot complexity was similar to clinical plans, with slightly more spots. Prediction and reconstruction averaged 0.02 s and 2.1 s/field. Conclusions: GenSpot generated machine deliverable PSMs from CT and dose whose MC doses closely matched clinical PSM doses in a single institution prostate SBRT cohort. This physics informed dose to spots framework may support automated PBS planning and adaptive replanning, pending broader validation.
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All authors Xueyan Tang, Hok Wan Chan Tseung, Mark Pepin, Jiasen Ma, David M. Routman, Doug J. Moseley, Brandon Reber, Jed E. Johnson, Jing Qian
Quantum Physics
PHASE: Pauli Hierarchical Assembly on Subdivided Elements for Quantum-Compatible Operator Synthesis
Tillman Philo and Caglar Oskay
Efficiently decomposing finite element stiffness
matrices into the Pauli basis is challenging due to the exponential growth of Pauli strings with problem size. A naive Pauli expansion requires $\Theta(8^{\lceil \log_2 N \rceil})$ operations, where $N$ denotes the number of degrees of freedom, rendering direct decomposition infeasible for large systems. Existing approaches exploit algebraic sparsity or operator structure but do not incorporate the
geometric organization intrinsic to finite element discretizations, and consequently exhibit poor scaling for stiffness
matrices. To address this problem, we introduce PHASE, a hierarchical, geometry-aware Pauli decomposition
algorithm that leverages recursive mesh partitioning to organize element contributions across multiple spatial scales. PHASE employs a hybrid strategy that combines full- and reduced-space Tensorized Pauli Decomposition with Fast Walsh-Hadamard Transform-based aggregation to assemble global Pauli coefficients efficiently. We show that this approach yields a dimension-dependent reduction in the exponential scaling exponent of Pauli assembly asymptotic complexity relative to existing methods, reducing the cost from $2^{2{\lceil \log_2 N \rceil}}$ to $2^{\gamma_d{\lceil \log_2 N \rceil}}$ with $\gamma_d < 2$ under standard mesh regularity and balanced partition assumptions. These results substantially improve the feasibility of
quantum-compatible operator synthesis for large-scale finite element models.
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Quantum Physics
Linear Combination of Hamiltonian Simulation with Commutator Scaling
Junaid Aftab, Dong An and Konstantina Trivisa
The Linear Combination of
Hamiltonian Simulation (LCHS) framework simulates dissipative linear dynamics by representing time
evolution as an integral over
unitary operators, which is discretized by quadrature and implemented via
Hamiltonian simulation. While existing analyses achieve near-optimal scaling in time and precision using norm-based quantities of the dissipative generator, we show that implementing the
Hamiltonian simulation steps with Multi-Product Formulas (MPFs) yields commutator-sensitive error and complexity bounds. We demonstrate that the quadrature rule affects not only discretization error but also commutator structure and query complexity. This dependence is quantified through post-quadrature analysis for abstract MPF error profiles and for general time-independent and local
Hamiltonians using known commutator-sensitive MPF error estimates. We compare uniform trapezoidal and free-scale sinh–sinh quadrature, showing improved quadrature-cardinality scaling for the latter, and illustrate the framework with applications to fractional
diffusion, advection–
diffusion, and open
quantum systems.
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Accelerator Physics · Cross-listed from cs.LG
Mahalanobis-Guided Latent OOD Detection for Hybrid ES-DRL Control in Time-Varying Systems
Shaifalee Saxena and Alexander Scheinker
In this paper, we study Mahalanobis-guided latent out-of-distribution (OOD) detection for test-time RL controller switching in nonlinear time-varying systems. RL controllers can quickly control high-dimensional systems within the training distribution, but their performance can degrade when time-varying dynamics produce unseen observations. We consider a combined ES–DRL controller, where RL provides fast in-distribution actions and bounded extremum seeking (ES) provides robust model-independent control under OOD operation. The key challenge is deciding when to switch. We train a variational autoencoder (VAE) on in-distribution beam-profile observations and use Mahalanobis distance in the VAE latent space to detect OOD beam profiles at test time. This OOD decision sets a binary switch that selects either the RL controller or the ES controller. We evaluate the approach in safety-critical particle accelerator control. In this setting, spatial magnet motion creates OOD beam profiles that were not seen during RL training. Visualization of the VAE latent space shows that the proposed method identifies this OOD scenario and provides an interpretable signal for switching between RL and ES in the combined controller.
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High Energy Physics (Theory)
Supersymmetry bicomplex of pure spinor AdS background
Thiago Oliveira Ferreira and Andrei Mikhailov
Infinitesimal deformations of $\text{AdS}_5 \times \mathbb{S}^5$ form a representation of the AdS supersymmetry
algebra. The structure of this representation has not yet been completely described in the literature. Some information can be obtained just from the fact that the space of deformations is the
cohomology of a nilpotent BRST operator. We can consider the bicomplex formed by the BRST operator and the Lie
cohomology differential, and its two spectral sequences. Their matching imposes some constraints on the structure of representations, which we start exploring in this paper. In particular, we clarify the structure of ghost number three zero modes.
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Quantum Physics
Optimizing Encoder Circuits of Entanglement-Assisted Quantum LDPC Codes via Beam Search
Aditya Sodhani, Pavan Kumar, Shayan Srinivasa Garani et al. (+1 more)
In encoder
circuits built on the stabilizer formalism, the dominant contribution to
circuit complexity comes from the use of controlled (CNOT) gates, making CNOT-count reduction a central
circuit-design objective.
Entanglement-assisted (EA)
quantum QC-LDPC codes offer strong error-correction capabilities with structured parity-check
matrices, but their practical use depends on efficient encoder
circuits and the availability of pre-shared Bell pairs (ebits). In this paper, we adopt a prior
entanglement-assisted QC-LDPC (EAQC) encoder construction. We formulate the encoder optimization as a search over GF(2) row operations that decompose the binary
matrix derived from its CNOT sub-sequence. We solve this problem using a beam search
algorithm guided by a Hamming-distance heuristic. For the tested EA
quantum QC-LDPC code families, the proposed method achieves CNOT-count reductions of 7.3-34.0% relative to the baseline EAQC encoder. The optimized
circuits also outperform the Patel-Markov-Hayes and greedy cost-minimization baselines, and are verified by stabilizer-tableau simulation. These results show that substantial encoder simplification is possible for structured EA QC-LDPC codes.
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All authors Aditya Sodhani, Pavan Kumar, Shayan Srinivasa Garani, Keshab K. Parhi