High Energy Physics (Theory)
On M2-, M5-, and D3-branes from 12d anomalies: an equivariant perspective on duality
Kiril Hristov and Pedro Vicente Marto
We revisit the twelve-dimensional anomaly
polynomial that has long been known to govern M5-brane worldvolume theories, together with its more recently proposed D3-brane counterpart. We show that these constructions naturally fit into the framework of equivariant integration, allowing the anomaly inflow formulas to be rewritten entirely in terms of equivariant volumes. In particular, we use the fact that the Bott–Cattaneo formula for the integral of powers of the global angular form on $S^{2k}$ emerges from the equivariant Euler-class integration of $\mathbb{C}^k$, with two copies glued antipodally at the north and south poles of the sphere. Building on this perspective, we generalize the anomaly construction to include both electrically and magnetically charged branes, thereby incorporating M2-branes as well as a dual formulation of D3-branes. This provides a unified framework encompassing a number of classical results together with several recent developments, and offers a natural interpretation of the recently proposed M2/M5 duality, arxiv:2604.06343, in terms of an AGT-like correspondence. Remarkably, it also leads to a direct reinterpretation of constant-map contributions in topological string theory as manifestations of M-theory anomalies.
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Atmospheric and Oceanic Physics
Impacts of Sulfate Injection Geoengineering on Particulate Matter with Diameter less than 2.5 {\mu}m
Lili Xia, Alan Robock and Simone Tilmes
Particulate matter with aerodynamic diameter less than 2.5 {\mu}m (PM2.5) is of great concern for human health. Here, for the first time, we examine the impact of sulfate aerosol geoengineering on PM2.5, using the output from the Geoengineering Large Ensemble (GLENS) project. GLENS is an ensemble of
climate model simulations injecting SO2 into the stratosphere to balance RCP8.5 forcing using the Community Earth System Model, version 1. GLENS geoengineering reduces global averaged surface PM2.5 mass concentrations compared with RCP8.5 and also changes PM2.5 composition with more percentages of organic carbon and sulfate. The total reduction of PM2.5 is a result of less
dust and sea salt concentrations.
Dust emission is declined under GLENS geoengineering because of increased soil moisture and leaf area index over desert regions, and less emission of sea salt is due to slower wind speeds when geoengineering is applied. Excluding
dust and sea salt, there is more global averaged PM2.5 under GLENS geoengineering relative to RCP8.5, predominantly due to more aerosol phase secondary organic aerosol (SOA). Since gas precursors of SOA are prescribed in the simulations, a cooler environment with geoengineering tends to transfer more gas phase SOA to aerosol phase. Changes in PM2.5 concentration and composition with applied geoengineering may have potential human health impact. Another new finding of this study is that the large amount of injected SO2 does not increase surface sulfate aerosol as a component of PM2.5, as the majority of sulfate aerosol reaching the boundary layer is in the coarse mode, which represents a very small fraction of the PM2.5. But the difference of deposition spatial distribution between geoengineering and RCP8.5 may have potential impacts on ecosystem.
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Optics
Hidden transverse-flow topology in partially coherent structured light
Rosario Martínez-Herrero and Ángel S. Sanz
Partial coherence is commonly viewed as a mechanism that reduces contrast or smooths intensity structure. Here we show that it can also encode hidden transverse-flow
topology. Starting from the cross-spectral density, we formulate a generalized transverse flux, an effective velocity field, and the associated flux trajectories for quasi-monochromatic partially coherent paraxial beams. This construction converts two-point correlation phases into local transport information and reduces to the usual coherent energy-flow picture in the single-mode limit. Because the generalized flux is obtained through a local differential operation on the cross-spectral density, the proposed trajectories are, in principle, reconstructible from sufficiently resolved phase-sensitive measurements of the complex second-order coherence function, subject to the regularization required by numerical differentiation. Two analytical beam families expose this hidden
topology. In twisted Gaussian Schell-model beams, a Gaussian intensity hides a distributed rotational flow with nonzero vorticity. In Laguerre-Christoffel-Darboux beams, sources with identical intensity profiles can have different flux
topology, producing either spiral or purely radial trajectories. Thus, intensity and coherence magnitude do not exhaust the physical information contained in the cross-spectral density: partial coherence can reorganize the hidden
topology of transverse optical transport.
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Materials Science
Paraexciton Excitation in Cu$_2$O under Laguerre–Gaussian Illumination
Nguyen Que Huong and David W. Facemyer
In Cu$_2$O the lowest yellow
exciton, the $\Gamma_2^+$ paraexciton, is optically inaccessible in conventional spectroscopy because transitions to this state are forbidden in both electric-dipole and electric-quadrupole approximations. We investigate whether optical fields carrying orbital angular momentum (OAM) can overcome this restriction. A microscopic
symmetry analysis identifies the gradient-assisted $l=5$ and direct $l=6$ OAM channels as the leading contributions that couple to the paraexciton, independent of the detailed radial profile of the optical field. Calculations for finite-waist Laguerre–Gaussian beams, however, show that the corresponding
matrix elements are strongly suppressed because the optical field varies only weakly over the
exciton Bohr radius. Thus, satisfying the OAM selection rule alone is insufficient: efficient excitation requires not only the correct angular
symmetry but also optical-field variations on the spatial scale of the
exciton. This second condition is achieved by localized OAM fields. Expressing the coupling in terms of the physical intensity-ring radius provides a direct comparison between the optical and excitonic length scales and reveals that the optimal localization is determined primarily by the
polynomial degree of the target cubic harmonic. For the degree-six $\Gamma_2^+$ paraexciton the strongest coupling occurs for an intensity-ring radius of approximately $6a_B$–$7a_B$. These results establish that paraexciton excitation is governed jointly by
symmetry and spatial localization: cubic
symmetry selects the allowed OAM channels, whereas the
polynomial degree sets the characteristic radial scale for efficient coupling. This work provides both the
symmetry framework and a practical design rule for engineering structured-light excitation of paraexcitons in Cu$_2$O.
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Strongly Correlated Electrons
Low temperature magnetic structure and lattice response in SmCuAs$_2$
M. G. Kim, C. Neupane, Y. Yu et al. (+6 more)
We investigated the structural and
magnetic properties of single-crystalline SmCuAs$_2$ using high-resolution synchrotron X-ray diffraction and X-ray resonant
magnetic scattering (XRMS) at the Sm $L_2$ and $L_3$ edges. Temperature-dependent diffraction measurements confirm that SmCuAs$_2$ maintains its tetragonal
symmetry from room temperature down to 8 K, with
lattice parameters showing anomalous behavior below the resistivity minimum ($T \approx$ 30 K). Notably, the c-axis
lattice parameter exhibits a plateau and subsequent increase near the Néel temperature, indicating magnetoelastic coupling. XRMS measurements reveal a commensurate
antiferromagnetic structure with a propagation vector \textbf{q} = (0, 0, 0.5). Our measurement shows that the Sm moments are aligned within the \textbf{ab} plane and arranged in a $++--$ stacking along the \textbf{c}-axis. Comparison with related RECuAs$_2$ compounds (RE = Pr, Nd, and Gd) suggests that in-plane moment orientation and associated
magnetic frustration play a key role in the emergence of the resistivity minimum. Differences in
spin-orbit and magnetoelastic coupling across the series highlight their importance in governing low-temperature transport behavior.
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All authors M. G. Kim, C. Neupane, Y. Yu, R. Acevedo-Esteves, C. Nelson, D. Evans, E. D. Mun, D. F. Agterberg, J.-W. Kim
General Relativity and Quantum Cosmology
New metric useful for studies of gravitational radiation from accelerating black holes of type D with any cosmological constant
Jiri Podolsky
We apply a convenient parametrization of all Plebanski-Demianski black holes of algebraic type D with the Kerr rotation, NUT twist, acceleration, electric and
magnetic charges, and any value of the cosmological constant $\Lambda$, recently found by Astorino. This represents a complete class of exact solutions to the Einstein-Maxwell-$\Lambda$ equations such that the (non-null) electromagnetic field is aligned with both the (geodesic, shear-free, double) principal null directions of the Weyl tensor. We derive a novel appropriate metric form and the corresponding canonical frames naturally adapted to both the de~Sitter-like ($\Lambda>0$) and the anti-de~Sitter-like ($\Lambda<0$) conformal infinity, and we demonstrate that these
geometric objects are useful for investigation of radiation properties. In particular, using the Fernandez-Alvarez-Senovilla criterion, it confirms that the gravitational radiation is present if, and only if, these black holes are accelerating.
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Pattern Formation and Solitons
Solitons and periodic wave solutions for complex Ginzburg-Landau equation modelling fiber lasers and nonequilibrium phenomena
Vladimir I. Kruglov and Houria Triki
New types of
soliton and periodic waves are identified for a nonlinear dissipative medium where the pulse propagation is governed by the cubic complex Ginzburg-Landau equation. We find that the dynamical equation for the pulse amplitude supports two distinct types of kink and antikink
solitons with different functional forms. It is found that the obtained kink and antikink
soliton waveforms occur under the same fixed inverse velocity. The results also indicate that the periodic waves can propagate with variety of wave forms such as sn, cn, dn and their rational forms as well. It is also shown that in the long-wave limit, the derived periodic waves degenerate into different bright and dark
soliton pulses. The stability analysis based on the theory of dispersive waves in nonlinear optics is developed. It is shown that some
elliptic and
soliton solutions are quasi-stable in the context of passive mode locking
lasers described by complex Ginzburg-Landau equation.
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Soft Condensed Matter
ESPResSo++: A Fast and Extensible Molecular Simulation Package for Coarse-Grained Models
Zhen-Hao Xu, James Vance, Nikita Tretyakov et al. (+9 more)
ESPResSo++ is an open-source software package for molecular dynamics (MD) simulations with a particular emphasis on coarse-grained (CG) models of soft matter systems. Written in C++ with a flexible Python interface, it is designed for high-performance computing (HPC) environments and supports massively parallel simulations through MPI. The package enables simulations of
polymers, membranes, colloids and complex fluids with a wide range of interaction models and advanced
algorithms.
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All authors Zhen-Hao Xu, James Vance, Nikita Tretyakov, Sebastian Eibl, Pavel Kus, Jakub Krajniak, Tristan Bereau, Horacio V. Guzman, Bin Song, Markus Rampp, Torsten Stuehn, Christoph Junghans
Classical Physics
How much work can you get by removing weights from a piston?
Joshua Samani
In thermodynamics, reversible adiabatic expansion can be understood as a limit of stepwise irreversible processes. We make this idea concrete by studying an ideal gas in an insulating cylinder with a frictionless piston supporting a load divided into $N$ blocks. If blocks are removed one at a time, the resulting expansion is a stepwise, irreversible process, but we prove that for a fixed total load, the work done by the gas approaches the reversible limit as the largest block mass tends to zero. On the way to this limit, an interesting work optimization question arises at finite $N$: how does the work done by the gas depend on the order and sizes of the removed blocks? Guided by numerical experiments accessible to advanced undergraduates, we motivate and then prove general answers to these questions. Our main finite-$N$ result proves that for fixed $N$, the optimal stepwise expansion corresponds to a
geometric progression of
equilibrium pressures, settling a
conjecture previously made by Andresen, Berry, Nitzan, and Salamon.
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Mathematical Physics · Cross-listed from math.AP
On the kinetic Fokker–Planck equation in curved geometry
Cédric Villani
These notes are devoted to the kinetic Fokker–Planck equation on the tangent bundle of a compact Riemannian
manifold, with motivations coming from relativistic kinetic theory of gases (à la Debbasch) and
geometric analysis (à la Bismut). They are developed in particular from collaboration with Fabrice Debbasch and Yann Ollivier. The presentation is mostly self-contained, intended for readers without much prior familiarity with
geometric analysis. Once the kinetic equations are reviewed, I expand the basic toolbox from functional and spectral analysis. Then the main focus is on global hypoelliptic $C^\infty$ regularization and hypocoercive exponential equilibration, both of which are addressed both in $L^2$ and $L^1$ settings. Various types of interpolation inequalities, spectral gap and entropic inequalities are established and used. Several existing results are simplified and unified, along with new ones. Some directions of research are mentioned.
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Astrophysics of Galaxies
VAPOLA - A multiyear, multiband polarization survey of AGNs and Sgr A* at millimeter wavelengths with ALMA II. Spectropolarimetric properties and their evolution from 2017 to 2023
Douglas Carlos, Ciriaco Goddi, Alejandro Mus et al. (+5 more)
We present a systematic analysis of the spectropolarimetric properties of a sample of 39 active
galactic nuclei and Sagittarius A* observed with the Atacama Large Millimeter/submillimeter Array during five VLBI campaigns between 2017 and 2023. We characterize the compact cores in total intensity and polarization, focusing on the behavior or the linear polarization fraction (LP), electric vector position angle (EVPA), and Faraday rotation measure (RM) over time and spectral domains. We investigate both individual objects–such as M87, Sgr A*, 3C273, and 3C279–and ensemble properties of different source classes, including flat-spectrum
radio quasars, BLLac objects, and other active
galaxies. While total intensity and spectral index are generally stable on weekly timescales, polarization properties often exhibit strong variability, with significant day-to-day changes in LP, EVPA, and RM. Several sources display large EVPA rotations accompanied by variations in LP and RM, in some cases coinciding with flaring activity. We observe that the magnitude of RM increases with observing frequency for all sources for which we have reliable multi-band measurements, consistent with Faraday rotation arising in a magnetized sheath surrounding the relativistic jet, although an origin in the
accretion flow–particularly in the case of Sgr A*–cannot be ruled out.
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All authors Douglas Carlos, Ciriaco Goddi, Alejandro Mus, Nicola Marchili, Kazi L.J. Rygl, Ezequiel Albentosa-Ruíz, Iván Martí-Vidal, The Event Horizon Telescope Collaboration
Materials Science
Data-Efficient Construction of Material-Specific Machine-Learning Interatomic Potentials from Ab Initio Molecular Dynamics Trajectories
Jonas Hänseroth and Christian Dreßler
Pretrained machine-learning interatomic potentials, so-called universal or foundation models offer an appealing starting point for atomistic simulations, but their accuracy for material-specific observables often remains limited without additional reference data (fine-tuning). Here, we systematically quantify how much first-principles data are required to convert universal models into ab initio-accurate material-specific potentials, and ask whether fine-tuning is necessarily preferable to training from scratch. We compare five universal MLIP frameworks, MACE-MP-0, SevenNet-0, GRACE-1L-OAM, MatterSim-v1-5M and ORB-v2, across seven chemically diverse systems incorporating rare and reactive events. Fine-tuning on only 10 AIMD-derived configurations is insufficient for the investigated systems; 200 configurations succeed in favorable cases, but the outcome remains strongly system-dependent. By contrast, 2000 AIMD configurations constitute a robust default, yielding low force and energy errors and reproducing the target material-specific observables. Moderately dense sub-sampling of the AIMD trajectory reduces the required trajectory length tenfold with little loss in model quality. Training from scratch on the same
datasets is competitive with, and often slightly more accurate than, naive fine-tuning for MACE and SevenNet, whereas GRACE requires more data. The energy profile for a sulfur-vacancy jump in MoS$_2$ reveals that low trajectory-level errors do not guarantee a correct reaction profile, highlighting the need for observable-level validation. Finally, we show that averaging independently trained models improves predictions in scarce-data regimes at no additional first-principles cost. Together, these results provide practical guidelines for converting limited AIMD reference data into reliable material-specific MLIPs for nanosecond-timescale simulations at near-DFT accuracy.
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Physics and Society · Cross-listed from cs.SI
Weaker Coherence, Weaker Reciprocity: Comparing the Semantic and Social Organization of Moltbook and Reddit
Favio Di Ciocco, Lucas Díaz Celauro, Sebastián Pinto et al. (+2 more)
Large
language models enable the creation of autonomous
agents that interact in social environments, raising the question of whether
agent-based platforms reproduce the organizational properties of human social networks. We compare Moltbook, a social network populated by AI
agents, with early Reddit, focusing on how communities organize and differentiate semantic content, using network analysis and NLP methods to characterize semantic coherence and diversity within and between communities, and their relationship to user activity. We find a systematic difference between the two platforms. Reddit communities show stronger semantic coherence, closer
alignment with community names, and greater semantic diversity, with individual communities spanning broader content and communities more differentiated from one another. This combination distinguishes Reddit from Moltbook, whose communities are more homogeneous, less differentiated, and increasingly misaligned with their names over time. Users on Reddit also participate across communities that are more semantically related than those connected by activity in Moltbook. At the interaction level, comment-network motif analysis shows Moltbook dominated by non-reciprocal, broadcast-like exchanges, whereas Reddit shows more reciprocal, chained interaction patterns. These results indicate that Reddit combines semantic coherence with diversity across organizational levels, a pattern not reproduced by the AI-
agent network.
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All authors Favio Di Ciocco, Lucas Díaz Celauro, Sebastián Pinto, Marcelo Kuperman, Pablo Balenzuela
Quantum Physics
A gauge-invariant theory of small Markovian errors in quantum gate sets
Juan Gonzalez De Mendoza, Corey Ostrove, Timothy Proctor et al. (+3 more)
Noisy logic operations on a
quantum computational register – e.g., one or more
qubits – can be described by transfer
matrices (a.k.a. CPTP maps or superoperators) that act linearly on the density
matrix representing the register's
quantum state. Collectively, these operations form a gate set. Gate sets have a gauge freedom; many gate sets that appear different actually predict the same experimental outcomes. A property of a gate set can be observable (and thus physically relevant) only if it is gauge-invariant. Unfortunately, no good gauge-invariant parameterizations of gate sets are known. We introduce the next best thing, a perturbative gauge-invariant parameterization of small Markovian errors in gate sets. We construct vector spaces of properties that are first-order gauge-invariant (FOGI). We show how to construct and understand FOGI properties, how to use them as coordinates to parameterize gate sets without gauge freedom, and how to extract approximately gauge-invariant error metrics.
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All authors Juan Gonzalez De Mendoza, Corey Ostrove, Timothy Proctor, Kevin Young, Erik Nielsen, Robin Blume-Kohout
High Energy Physics (Phenomenology)
Leading order quark-antiquark-W-boson vertex in the presence of a magnetic field
Alejandro Ayala, Alejandro Lopez, Ana Julia Mizher et al. (+2 more)
We compute the leading order modification to the
quark-antiquark-$W$-
boson vertex in the presence of a constant and uniform
magnetic field, specifically for the case where the
quark and antiquark are the $u$ and $\bar{d}$, respectively. We find the selection rules for transitions where the $u$, $\bar{d}$, and $W$-
boson occupy arbitrary Landau levels. We show that, for the particular case where the initial particles each occupy the lowest Landau level, the $W^+$ is also produced in the lowest Landau level with a single polarization aligned with the
magnetic field. We also illustrate the general findings by computing the case of transitions between low lying Landau levels and show the correspondence between the polarization vectors for the $W$-
boson and the polarization states for the
quark and the antiquark.
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All authors Alejandro Ayala, Alejandro Lopez, Ana Julia Mizher, Manuel Emiliano Monreal Cancino, Norberto Scoccola
Strongly Correlated Electrons
Antiferroquadrupolar Order in Altermagnetic CoF$_2$
Daniel Halliday, Laura Pöysti, Chung Xu et al. (+5 more)
Altermagnets host non-relativistic
spin-split electronic states whose microscopic origin is theoretically linked to a hidden charge order, yet experimental studies of this charge order are limited. We therefore investigate charge order within CoF$_2$, a $d$-wave altermagnetic compound with a rutile
crystal structure and $\Gamma$-point antiferromagnetism. Combining resonant elastic X-ray scattering,
symmetry analysis and ab initio calculations, we directly observe charge ordering and identify it as antiferroquadrupolar in nature. Via electronic structure calculations, we show that the experimentally observed antiferroquadrupolar order gives rise to the characteristic altermagnetic
spin-splitting, thereby establishing empirical evidence for the decomposition of the altermagnetic order parameter into
magnetic and charge degrees of freedom. We hence demonstrate that antiferroquadrupolar order is the microscopic origin of altermagnetism in CoF$_2$, with implications to the wider family of rutile altermagnets. Furthermore, our approach is applicable to studying altermagnetism in general, having demonstrated that resonant elastic X-ray scattering can serve as a direct probe of the charge multipoles that underpin
spin-split electronic states in these materials.
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All authors Daniel Halliday, Laura Pöysti, Chung Xu, Daniel A. Mayoh, Didier Wermeille, Dharmalingam Prabhakaran, David R. Bowler, Roger D. Johnson
Astrophysics of Galaxies
High-spectral-resolution Observations of the [S II] Emission-line Doublet in the Filamentary Nebula Surrounding NGC 1275
Benjamin Vigneron, Julie Hlavacek-Larrondo, Carter Lee Rhea et al. (+10 more)
We analyze new high-spectral resolution SITELLE observations (R = $\lambda/\Delta\lambda$ = 7000) of the filamentary nebula surrounding NGC 1275, central
galaxy of the Perseus cluster. We present here analysis of the \sii$\lambda6716$ and \sii$\lambda6731$ emission line doublet, using its ratio to determine the electron density of the optically emitting filaments. We compare these measurements with electron densities derived from deep Chandra X-ray observations of the intra-cluster medium (ICM) to determine if any correlations in density can be found. We report the detection of a clear dichotomy between the outer filaments, displaying on average lower \sii\text{ }emission line ratio of $\sim 1.1$ and the inner filaments displaying higher ratios of $\sim 1.3$. These results indicate that most of the gaseous filaments lie close to the low-density threshold for the density measurement of $\sim 10^2\text{ cm}^{-3}$. Using radial profiles, we find that the inner filaments have a roughly constant density, whereas the ICM density decreases with radius. In the outer filaments, we observe hints of local connections between the densities of the ICM and optical filaments, but no clear correlation seems to be observed overall. We also combined these density measurements with cold molecular CO gas observations to derive a relationship between temperature, density and pressure for the multiphase environment surrounding NGC 1275. Finally, we investigated potential models to explain the observed density measurements and explored similar studies of filamentary nebula around other central
galaxies of cool-core
galaxy clusters.
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All authors Benjamin Vigneron, Julie Hlavacek-Larrondo, Carter Lee Rhea, Christoph Pfrommer, Greg L. Bryan, Megan Donahue, Alastair Edge, Andrew Fabian, Michael McDonald, Annabelle Richard-Lafferrière, Laurie Rousseau-Nepton, G. Mark Voit, Norbert Werner
Fluid Dynamics
A physics-informed SUPG-stabilized finite element framework with shock-capturing for simulating inviscid high-speed flows around a cylinder
Süleyman Cengizci and Ömür Uğur
This study presents a hybrid computational framework for simulating non-reacting inviscid high-speed flows of nitrogen gas (N$_2$) around a circular cylinder. Owing to the strongly convection-dominated nature of the compressible Euler equations, the compressible-flow streamline-upwind/Petrov–Galerkin (SUPG) formulation is combined with the YZ$\beta$ shock-capturing technique to stabilize the finite element discretization in the presence of strong discontinuities. Building upon the stabilized solution, a physics-informed neural network (PINN) is employed as a post-processing correction stage (\underline{P}INN-\underline{A}ugmented \underline{S}UPG with \underline{S}hock-\underline{C}apturing—PASSC). The network is anchored to the finite element solution through a shock-weighted data-consistency loss, while the governing equations are enforced in a conservative space–time control-volume form supplemented by macroscopic conservation windows, an
entropy-admissibility penalty, and the boundary conditions of the underlying problem. Two-dimensional simulations are performed for free-stream Mach numbers ranging from $2.0$ to $12.0$, and the results are assessed against analytical normal-shock and stagnation relations, the semi-empirical Billig correlation, and reference solutions from the literature. The correction is designed to improve the numerical representation of shocks by reducing localized discretization-induced oscillations and mesh-scale serrations while preserving the agreement of the stabilized solution with the analytical and semi-empirical reference quantities.
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Materials Science
Higher-order nonadiabaticity governs the temperature dependence of the phonon spectrum
Nina Girotto Erhardt and Samuel Poncé
Nonadiabatic effects determine the frequency and linewidth of coupled
phonon modes, shape of Kohn anomalies and have important implications on many material properties. State-of-the-art ab-initio nonadiabatic
phonon self-energy relies on an infinite electron lifetime approximation, which cannot capture the temperature dependence of the
phonon spectrum, neglects long-wavelength intraband
phonon decay, and exhibits exaggerated
phonon splitting. In MgB$_2$, we show how the higher-order nonadiabatic
phonon corrections mitigate these deficiencies, yielding linewidths in a closer experimental agreement and a dome-like coupling strength temperature dependence.
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Materials Science
Coherent Phonon Blocking in Superlattices
Anil Erol, Xiang Hua, Kirby Myers et al. (+9 more)
At cryogenic temperatures,
phonons become one of the dominant energy carriers and thus can strongly influence the performance of electronic and sensing devices. In this work, we present a wave-mechanics based framework that predicts
phonon transmission and thermal resistance of arbitrarily thick superlattices while retaining all acoustic branches, mode-conversion pathways, and angles of incidence. By enforcing phase coherence, our model predicts frequency-dependent transmission through arbitrary multi-layered structures.We use a genetic
algorithm (NSGA-II) to efficiently select both materials and layer thicknesses. Our success criterion is that constituent layers satisfy the quarter-wavelength condition of the dominant
phonon frequencies at a target temperature. This strategy identifies novel
bilayer combinations that achieve thermal resistance of up to 3000 times greater than previously reported superlattices. The identified superlattices are poised to advance any technology that relies on coherent acoustic scattering, from ultra-low-temperature thermal insulation in superconducting flip-chip assemblies to
phonon-blocking components in micro- and nano-electromechanical systems.
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All authors Anil Erol, Xiang Hua, Kirby Myers, Lawrence Friedman, Alexander Marakov, Melissa G. Loving, Joshua Shipman, Arsha Mamoozadeh, Sarah Millen, Ronald J. Warzoha, Jeremy Clark, Robert M. Young
Materials Science
When do machine-learned exchange-correlation improvements inherit into density-functional tight binding?
Can Polat, Mustafa Kurban, Erchin Serpedin et al. (+1 more)
Machine-learned exchange-correlation functionals correct band gaps at near-semilocal cost, while density-functional tight binding reaches the $10^3$-$10^6$-atom regime; combining them assumes that a better parent yields a better parameterization, but we show it does not. Current-generation functionals are orbital-dependent generalized Kohn-Sham operators, whereas the parameterization channel is built on a multiplicative potential, preventing exact representation. Using the transfer ratio, the surviving fraction of a parent-level change, we find anti-transfer: coherently negative ratios across four covalent
semiconductors move the gap in the wrong direction, consistent with a molecular proxy and an r$^2$SCAN control. The minimal-basis overgap is dominated by the on-site convention rather than basis incompleteness; correcting the on-site block removes most of it, while one $d$-polarization shell closes a further $16$-$40%$, depending on the placement of the empty $d$ level, which no free-atom
eigenvalue uniquely fixes. Occupied-
manifold enhancements, ionic and closed-shell repulsive potentials, and rocksalt-
oxide gaps inherit, whereas elemental and III-V covalent networks inherit neither gaps nor repulsive potentials and
oxide networks inherit only the latter. We screen 23 elements and release the parameter sets, showing that the transfer ratio provides a cheap pre-test before any parameterization campaign.
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All authors Can Polat, Mustafa Kurban, Erchin Serpedin, Hasan Kurban
Instrumentation and Methods for Astrophysics
Sub-Pixel Calibration of CMOS Sensors for Precision Astrometry
M. Shao and I. Hahn
Many sources of systematic error are important to centroid the position of a
star below the level of $10^{-4}$ of the FWHM of the
stellar image. One of the more important sources of centroiding error is the imperfect position of the pixels in a focal plane array. In this paper, we discuss the calibration of pixel position of multiple commercial CMOS detectors. Focal plane arrays are
semiconductor devices fabricated with 10's nanometer precision. However, the effective location of a pixel can be biased if there's a QE gradient across the pixel. We typically see pixel position variations of 1–3% of a pixel in most CMOS imagers. This paper describes how we measure the position of each pixel below the $10^{-3}$ pixel level. We also describe how this information might be used in a least square fitting of an airy spot to obtain a higher accuracy position of the centroid of the PSF.
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Instrumentation and Methods for Astrophysics
Enabling Quantitative Polarimetry for Keck/NIRC2: Preliminary Mueller Matrix Model Calibration
Manxuan Zhang, Briley L. Lewis, Maxwell A. Millar-Blanchaer et al. (+27 more)
The Keck/NIRC2 infrared imager was upgraded in 2025 with dual-beam polarimetric observing modes spanning approximately 1.1–4.1 microns (JHKL' bands). We present a preliminary JHK calibration of NIRC2 Polarimetry using a wavelength-dependent Mueller
matrix model of the Keck tertiary mirror (M3), half-wave plate (HWP), image rotator (IMR), downstream optics, and Wollaston prism. We constrain the model downstream of M3 using dome flat sequences spanning ten HWP and nine IMR angles in each band. Although the model reproduces the dominant modulation, the residuals show structure dependent on HWP and IMR angle. Measurement
matrix inversion of unpolarized standard
star observations gives M3 diattenuations of 0.0119+/-0.0009, 0.0098+/-0.0004, and 0.0068+/-0.0005 in J, H, and Kp, substantially closer to Fresnel predictions for aluminum than the values derived from dome flats. The larger dome flat modulation may indicate polarization in the incident dome illumination or Mueller
matrix model inaccuracies. These results establish an initial calibration framework while motivating improved input polarization constraints, fixed HWP parameters from previous laboratory measurements, model validation with polarized standard
stars, and extension to L'.
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All authors Manxuan Zhang, Briley L. Lewis, Maxwell A. Millar-Blanchaer, Eduardo Marin, Jayke S. Nguyen, William Melby, Carlos Alvarez, Jaren N. Ashcraft, Mahawa Cisse, Charles-Antoine Claveau, Jacques-Robert Delorme, Greg Doppmann, Michael P. Fitzgerald, Matthew Freeman, Percy Gomez, Trisha Hammen, Ryan Hersey, Nemanja Jovanovic, Marc Kassis, Scott Lilley, Jessica Lu, James E. Lyke, Keith Matthews, Dimitri Mawet, Thomas McIntosh, Max Service, Lauren Simmons, Jacob Taylor, Rob G. van Holstein, Ed Wetherell
Quantum Physics
Minimality of the Pure Qubit ZX Calculus
Harry K. Stoltz and Renaud Vilmart
The ZX calculus is a graphical
language for
reasoning about
quantum processes. In this paper, we develop a minimal pure-
qubit ZX calculus based on the work of Vilmart [arXiv:1812.09114], Backens, Perdrix, and Wang [arXiv:1709.08903], and Stoltz [arXiv:2606.12383]. This resolves a problem that has remained open for nearly a decade, since completeness was first proved. Specifically, we show that $(I_r)$ is derivable and establish the necessity of $(B)$ and $(I_g)$, yielding two complete and minimal rulesets.
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Quantum Physics
Chiral Nonlinear Optics and Optical Control
Cedric Dufresne, Annabelle Makowski and Nir Rotenberg
Chiral light-matter interactions lie at the heart of emerging technologies such as
quantum network protocols and
quantum logic gates. In the few
photon regime, it has been shown that
chiral interactions between
photons and a waveguide-embedded two-level
quantum emitter can break reciprocity and impart a directional $\pi$ phase shift while the transmission remains intact. In this work, we present a model for multicolor,
chiral nonlinear interactions in waveguides using a Green's Tensor formalism. We challenge previously held notions and demonstrate the complex
photon dynamics hidden in multicolor light-matter interactions in the few
photon regime. By modulating a stronger control beam, we can manipulate a weaker signal beam that contains much less than a single
photon per emitter lifetime, on average. We develop equations for the transmission of the signal
photons and removing the control
photons to uncover the true strength of these nonlinearities, which we show is stronger than what is possible in symmetric geometries. The model predicts tunable unity extinction and up to 30% amplification in the signal, a $\sim$100x increase from standard predictions in which control
photons are present. We also predict a tunable 0-$\pi$ phase shift via control modulation with significant robustness to emitter imperfections. Our model opens a new regime of directional nonlinear
quantum light-matter interactions for study, providing a route to efficient all-optical control of
photons.
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Instrumentation and Methods for Astrophysics
An open-source data processing pipeline for Keck / NIRC2-Polarimetry
Briley L. Lewis, Maxwell A. Millar-Blanchaer, Rebecca Zhang et al. (+3 more)
The Keck/NIRC2 infrared imager was recently upgraded with a new suite of polarimetric observing modes. This polarimetry upgrade (referred to as NIRC2-Pol) will open up a wide range of new astronomical studies, including investigations of
exoplanets, the
Galactic center, active
galactic nuclei and the
solar system. Astronomical polarimeters require sophisticated data reduction, especially for quantitative polarimetry requiring the use of a Mueller
Matrix model for instrumental polarization calibration. This work presents the design of a flexible, user-friendly, open-source data processing pipeline intended for use with NIRC2-Pol, summarizing its key steps and details of its ongoing implementation.
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All authors Briley L. Lewis, Maxwell A. Millar-Blanchaer, Rebecca Zhang, Jayke Nguyen, Max Brodheim, Ashish Uhlmann
Mathematical Physics · Cross-listed from math.QA
Complex Hadamard Matrices - Quantum Symmetries, Equivalence and Non-Local Games
Michael Brannan, Daniel Gromada, Roberto Hernández Palomares et al. (+1 more)
We consider
quantum group generalizations of the action of monomial
matrices on complex Hadamard
matrices. This gives rise to various notions of
quantum symmetries and
quantum equivalences of Hadamard
matrices. We show that if one acts by a certain largest monomial
quantum group, then all Hadamard
matrices of a given size become
quantum equivalent. Taking a more restrictive quantization leads to a notion of $s$-
quantum equivalence. We exhibit examples of Butson
matrices of the same size and order that are not $s$-
quantum equivalent for any choice of $s$. We also show that $s$-
quantum equivalence is operationally modeled by a synchronous non-local “Hadamard equivalence” game. Our methods are largely graphical calculus based, using categories generated by complementary spiders. We use these same tools to study
quantum affine equivalence of
quantum groups, and prove that all finite
quantum groups of the same size are
quantum affinely equivalent. We also provide a short graphical proof of a result of Kasprzak–Sołtan–Woronowicz asserting that
quantum symmetries of finite
quantum groups must be classical.
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All authors Michael Brannan, Daniel Gromada, Roberto Hernández Palomares, Nicholas Priebe
Chemical Physics
Separation of Flexible Enantiomers Using Shear Flow
Minh Nhat Pham, Levi Cherek and J. Daniel Gezelter
Mechanical separation of enantiomers is an attractive alternative to synthetic methods for producing enantiopure samples. Shear flow that produces solution vorticity has been shown to be a viable means for separating
chiral objects on the micro- to nano-scale due to the tensorial nature of the interactions between
chiral objects and the surrounding fluid. A recently-developed theory of molecular pitch characterizes these interactions using the resistance tensor and predicts the shear-induced separation of drug-like molecules from their optimized molecular geometries. We present a molecular dynamics study on the effects of incorporating molecular flexibility into the molecular pitch framework. We also evaluate the potential for enantiomeric separation of two drug molecules: bicalutamide (Casodex) and montelukast sodium (Singulair). Simulations reveal the emergence of flexibility-induced pitch distributions that result from conformational changes occurring in a realistic solvent environment. However, these distributions are weakly influenced by the solvent identity and the shearing process, producing mean scalar pitch values that are close to those from optimized gas phase structures. Despite the opposing effect of translational
diffusion at the molecular scale, racemic mixtures of flexible enantiomers show linear rates of separation at the 10 ns timescale, and we predict that cm-scale separation can be achieved within hours. Additionally, we provide estimates for parameters of a Taylor-Couette device for generating laminar shear flow, as well as considerations for future experiments.
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Soft Condensed Matter
Physics-Informed Symbolic Regression for Predicting the Glass Transition Temperature of Alkali Borate Glasses
Leonardo dos Santos Vitoria, Marcio Luis Ferreira Nascimento, Susana de Souza Lalic et al. (+1 more)
The glass transition temperature ($T_{g}$) of alkali borate glasses is strongly composition-dependent and difficult to predict from first principles due to the structural complexity of the boron network. Here, we apply physics-informed symbolic regression (combining evolutive search with physically meaningful descriptors) to derive an interpretable closed-form expression for $T_{g}$ in the $x\mathrm{M}_2\mathrm{O}\cdot(100-x)\mathrm{B}_2\mathrm{O}_3$ glass family, with M = Li, Na, and K and $x$ expressed in mol%, and subsequently extrapolate it to M = Rb and Cs. The resulting model achieves a root-mean-square error of 14-16 K while maintaining clear physical interpretability, explicitly capturing the interplay among $T_{g}$, structural dissociation energy, and network packing. Critically, models built on the Rigid Unit Packing Fraction (RUPF) yield substantially more realistic $T_{g}$ predictions than those using the conventional Atomic Packing Fraction (APF), as APF overestimates structural
rigidity at intermediate compositions. The fitted dissociation energies are further validated against the revised Makishima-Mackenzie model, confirming that the inferred parameters are physically consistent, not merely statistically effective, within the alkali borate family. Finally, Monte Carlo uncertainty quantification reveals that prediction uncertainty is highest in the compositional regions associated with the boron anomaly, directly linking model limitations to a known structural transition in these glasses. This result highlights the potential of physics-informed symbolic regression as a transparent and interpretable alternative to black-box models for property prediction in glass systems.
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All authors Leonardo dos Santos Vitoria, Marcio Luis Ferreira Nascimento, Susana de Souza Lalic, Daniel Roberto Cassar
Statistical Mechanics
Exact Thermoelectric Transport Coefficients and Figure of Merit for Graphene Photothermoelectric Devices from a Finite Zeta-Function Mott Series
Luis Daniel Villa Cortes, S. R. Valluri, Atul Jhalani et al. (+2 more)
The standard Mott formula is widely used to describe thermoelectric transport, but it becomes less accurate when the temperature is not much smaller than the
Fermi energy. In this work, we develop an all-orders extension of the Mott approach using a series of Riemann
zeta functions. We show that when the transport function is a
polynomial, the series ends after a finite number of terms, giving exact results within the model. We apply this method to
graphene photothermoelectric devices using a quadratic conductivity model. The results provide closed-form expressions for the Seebeck coefficient, Lorenz ratio, and electronic figure of merit. The analysis shows that the Seebeck coefficient reaches a maximum instead of increasing indefinitely, while the Wiedemann-Franz law can be significantly violated at higher temperatures. We also find that disorder reduces the thermoelectric performance and that the electronic figure of merit has an upper limit in the clean
graphene model. Finally, we discuss the effect of radiative heat transport on the figure of merit. These results provide a simple analytical way to study
graphene thermoelectric transport beyond the usual low-temperature Mott approximation.
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All authors Luis Daniel Villa Cortes, S. R. Valluri, Atul Jhalani, Ajay Soni, P. C. Deshmukh