Soft Condensed Matter
Biomolecular condensates and their pathologies: A colloidal, interfacial, and transport perspective
Vineeth Godavarti and Vinny Chandran Suja
Biomolecular condensates are micron-scale, membraneless compartments that concentrate
proteins and nucleic acids by
liquid-
liquid phase separation (LLPS). Condensates play critical roles in transcription, mRNA metabolism, stress responses, and signaling across the
cell, with their dysregulation increasingly correlated with several pathologies spanning neurodegeneration, cancer, cardiometabolic disease, and viral infections. The emergent biology of condensates can be cohesively viewed through the framework of colloidal, interfacial, and transport phenomena. Here we review the condensate literature through this joint lens, treating each condensate as a biological colloid whose behavior is captured by four measurable physical quantities: a Flory–Huggins interaction parameter that determines whether the dense phase forms at all, a partition coefficient that dictates the degree of client molecule accumulation, a viscoelastic relaxation time that sets whether the dense phase responds as a
liquid or a solid, and an interfacial tension that governs droplet shape and interfacial dynamics. Each quantity is traced to its physical origin, its measured range in biological condensates, and the techniques that quantify it, for both three-dimensional droplets and two-dimensional membrane-tethered condensates. Interpreting disease as the displacement of these physical quantities from their functional ranges, we reorganize condensate pathologies into a small set of physical failure modes — saturation concentration dysregulation, aberrant aging and
liquid-to-solid transitions, disrupted partitioning, interfacial aggregation, and pathogen hijacking — and show how the same parameters become design variables for condensate-targeted drugs and engineered coacervate delivery vehicles. The review concludes with open questions at the interface of condensate biology and colloidal and interfacial science.
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Plasma Physics
A New Degree of Freedom in Stellarator Coil Design
Sophia A. Henneberg and Annika Zettl
Reversed toroidal field (RTF) coils introduce a new degree of freedom in stellarator coil design. While the total
plasma-linked current is fixed by Ampere's law, compensating RTF currents allow the modular-coil current to exceed this value without altering the net linkage. This redistribution decouples key coil constraints and modifies the external coil geometry without significantly compromising the confining
magnetic field. As a result, the achievable coil-
plasma separation can be increased in the configurations studied, potentially enabling more compact stellarator designs.
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Materials Science
Atoms that Matter: Largest Materials Datasets Are 99% Redundant, and Local Chemistry Can Guide the Required 1%
Evgeny Moerman, Igor Poltavsky, Anton Charkin-Gorbulin et al. (+1 more)
General-purpose machine-learning force fields (MLFFs) for materials are now trained on the order of $100$ million structures, assuming transferability requires such scale. We test this premise on OMat24, the largest available materials
dataset, by training MACE models on subsets of $6.5$ million atoms, less than $1\%$ of OMat24, selected in three complementary ways: at random, by latent-space clustering of a pretrained MLFF (DIRECT), and by a new model-free method maximizing the diversity of discrete, interpretable local environments (EnvTok). All three models approach the full-data reference MACE-OMAT-0 model to within a few tens of $\mathrm{meV}/\mathring{\mathrm{A}}$ in forces, and remain close to or exceed it on formation energies, elastic moduli, heat capacities, Li$^{+}$ migration barriers, and molecular-dynamics stability up to $3000\,$K and $500\,$GPa. This near-independence from the selection strategy shows that chemical environment diversity, not size, defines OMat24's information content: the remaining $99\%$ of structures are largely redundant. Broad sampling of chemical space thus remains essential, but reference labels are needed only for structurally and chemically distinct configurations. Using atomic positions and species, optionally augmented by
magnetic moments, EnvTok identifies these before any labelling or training, yielding compact, architecture-independent
datasets. This hundredfold reduction makes hybrid-DFT or higher-level relabelling of general-purpose training sets feasible, and frees computational budget for extending environmental coverage and multi-fidelity learning.
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All authors Evgeny Moerman, Igor Poltavsky, Anton Charkin-Gorbulin, Alexandre Tkatchenko
Nuclear Theory
Deconfinement and the Charge Susceptibility Matrix of QCD
Christopher Grace, Brady Mowbray and Christopher Plumberg
At sufficiently high temperatures,
lattice Quantum Chromodynamics (QCD) calculations predict that nuclear matter undergoes a rapid crossover to a novel, deconfined state known as the
quark-gluon
plasma (QGP), in which
quark flavors essentially behave like independent particles. Here we explore the nature of this transition by introducing two new thermodynamic observables which we refer to as the diagonality and the rescaled
curvature of the QCD equation of state (EoS). By comparing these observables in the case of
lattice QCD calculations with those of simple toy models and more sophisticated hadronic resonance models, we show that both the diagonality and the rescaled
curvature provide complementary insights into the degree of independence between different
quark flavors and the underlying degrees of freedom in the system as functions of temperature. We propose that these observables may help to clarify the nature of the transition region and the onset of deconfinement in nuclear matter.
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Solar and Stellar Astrophysics
TESS Pulsation Timing Reveals the JWST Calibration Star HD 158485 as a Double-pulsator Binary
Chenglong Lv, Ali Esamdin, Shuguo Ma et al. (+5 more)
HD~158485 is an A-type $\delta$~Scuti
star in the CALSPEC network and the JWST absolute-flux calibration program. Gaia DR3 assigns it a binary classification probability close to unity but provides no orbital solution. Using TESS observations from Sectors 14–26, 40–41, 47–60, and 73–86, we measure the pulsation phases of six $\delta$~Scuti modes. The frequencies form two groups with opposite light-travel-time delays, revealing two pulsating components. A direct light-curve forward model yields an orbital period of $P_{\rm orb}=382.80^{+0.80}_{-0.76}$~d, eccentricity $e=0.242^{+0.045}_{-0.046}$, projected light-time amplitudes of $195.8^{+9.2}_{-8.9}$ and $239.7^{+6.8}_{-6.8}$~s, and a dynamical mass ratio of $q=M_B/M_A=0.818^{+0.046}_{-0.045}$. A blind prediction based only on the first two long TESS campaigns reproduces the third campaign without updating the orbital parameters, with a Pearson correlation coefficient of $r=0.983$. Its held-out rms is 83.8~s, compared with 289.9~s when the period is fixed at 365.25~d. A 5.15-$\sigma$ Hipparcos–Gaia EDR3 proper-motion anomaly independently indicates unresolved astrometric motion. The unresolved companion can also affect spectrophotometric predictions: a conditional PB2-constrained two-atmosphere model differs from the corresponding single-
star atmosphere prediction by 1.6% over 1–5~$\mu$m and 2.5% over 5–28~$\mu$m. HD~158485 therefore shows that a calibration-relevant binary can lack a catalogued orbital solution while two independent pulsation clocks reveal and measure its orbit.
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All authors Chenglong Lv, Ali Esamdin, Shuguo Ma, Shahidin Yaqup, Haozhi Wang, Ayzada Jmahali, Jianwei Yao, Kedieryemu Kamili
Mesoscale and Nanoscale Physics
Direct Observation of Chirality-Dependent Berry Curvature Dipole via Cross-Axial Nonlinear Hall Effect in Trigonal Te
Jaehyun Lee, Junhee Shin, Daryll J. C. Dalayoan et al. (+8 more)
Quantum geometric quantities, such as Berry
curvature (BC) and
quantum metric, are known to govern the physical and topological properties of materials, making access to these quantities critically important for the comprehensive understanding of the materials. Chiral
crystals offer a natural platform in which structural handedness can control
quantum geometry and nonlinear transport, but direct experimental access to the
quantum geometric quantities has remained elusive. Here, we show that trigonal tellurium (Te) hosts an enantiomer-dependent Berry
curvature dipole (BCD) that can be accessed through the measurement of cross-axial nonlinear Hall effect (NHE), unlike previously studied in-plane configurations where the BCD contribution vanishes. Angle-resolved measurements on left- and right-handed Te devices reveal a second-order transverse response whose sign reverses with
crystal chirality. The extracted cross-axial nonlinear susceptibility, $\chi_{yxz}$, exceeds the in-plane susceptibility, $\chi_{xxx}$, by more than two-folds, indicating a strong BCD-driven contribution. First-principles calculations attribute this behavior to a topologically nontrivial hedgehog-like BC texture near the H points and predict a BCD that reverses sign between opposite enantiomers, consistent with experiment. These results establish cross-axial nonlinear Hall transport as a
symmetry-selective probe of chirality-controlled
quantum geometry in tellurium and related chiral materials.
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All authors Jaehyun Lee, Junhee Shin, Daryll J. C. Dalayoan, Miju Park, Changhee Sohn, Gang Qiu, Noejung Park, Binghai Yan, Tony Low, Hosub Jin, Seon Namgung
Soft Condensed Matter
Explicit Solvents Reverse Temperature Dependence of Phase Behavior in Charged Fluids
Pierre J. Walker and Zhen-Gang Wang
In most theories of electrolyte and polyelectrolyte solutions, the solvent is treated implicitly as a dielectric continuum. While this approximation has enabled major advances, it neglects coupling between ionic and dipolar degrees of freedom. Using molecular dynamics simulations and the mean-spherical approximation, we show that this coupling qualitatively alters electrostatically driven phase behaviour. At finite ion concentrations, many-body ion-dipole correlations reverse the temperature dependence of effective electrostatic interactions, leading to upper-critical solution temperature (UCST) behaviour in direct contrast to the lower-critical solution temperature (LCST) behaviour predicted by implicit-solvent electrostatic theories. This phase reversal arises from ion-induced suppression of local dipolar screening, a collective effect inaccessible to pairwise implicit-solvent descriptions.
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Statistical Mechanics
Competitive scaling of small-subsystem-optimization heuristics for LABS
Ginger E. Lau and Adil A. Gangat
The low autocorrelation binary sequences (LABS) problem, often formulated as a
spin-
lattice energy-minimization problem, is a combinatorial optimization problem with a very rugged energy landscape. We demonstrate that iterative optimization of very small subsystems of n
spins that are decoupled from the rest of the system achieves global optimization of LABS with a time-to-solution scaling that is competitive with heuristics that optimize the global system of N
spins directly. Our isolated-subsystem heuristic with n = 4 achieves a time scaling of O(1.333^N ) on the interval N = [27, 60], while the current state-of-the-art classical and
quantum scalings are respectively O(1.34^N ) and O(1.21^N ). Our results suggest that specialized optimization hardware with only small numbers of logical
spins may be of practical relevance.
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Nuclear Theory
Separating entanglement at emission from femtoscopic correlations
Isaac Vidaña
We investigate how femtoscopic correlations modify the relation between the
spin entanglement of emitted particle pairs and that of pairs selected at a given relative momentum. For two
spin-$\frac{1}{2}$ particles, we show that the momentum-selected
spin state can be entangled even when the corresponding state at emission is separable. We derive a momentum-dependent separability criterion that determines whether the observed
spin correlations require
entanglement at emission. As an application, we consider a pair of identical $\Lambda$ hyperons, for which
quantum statistics and final-state interactions affect the singlet and triplet
spin channels differently at low relative momentum. Our results provide a framework for using experimentally accessible
spin correlations to investigate
entanglement at emission.
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General Relativity and Quantum Cosmology
Non-Stationary Wormholes and Matter Source Reconstruction in General Relativity
Geová Alencar, Tiago Crispim, Roberta Dárlla et al. (+1 more)
We investigate non-stationary wormhole geometries in General Relativity embedded in evolving cosmological backgrounds. We employ a Simpson-Visser-like regularization of the temporal coordinate of the $(n+1)$-dimensional FLRW metric, together with a homogeneous Cuscuton field, to construct cosmological backgrounds in which the scale factor remains finite and non-zero at the would-be initial singularity. We then consider two specific dynamical wormhole geometries: the four-dimensional defect wormhole and the topologically charged Perry-Mann type wormhole. We show that the former can be supported by a canonical scalar field with vanishing potential, while the latter requires a mimetic matter sector to support its spatial structure, with the Cuscuton governing the cosmological
evolution in both cases. We subsequently generalize the analysis to a separable non-stationary spacetime and derive a scaling condition that strongly constrains the admissible matter sources. In particular, for minimally coupled scalar and nonlinear electrodynamics fields, this condition removes the functional freedom available in static reconstruction schemes. We show that, within this framework, regular, asymptotically flat wormhole geometries cannot be obtained while simultaneously satisfying the required smoothness and reflection
symmetry conditions. Our results illustrate both the possibility of constructing specific non-stationary wormholes in regular cosmological backgrounds and the restrictions that arise when attempting to generalize such constructions to arbitrary spatial geometries.
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All authors Geová Alencar, Tiago Crispim, Roberta Dárlla, Ricardo Landim
Fluid Dynamics
AI Meets Turbulence Modeling: Complex Systems Perspective
Sharath S. Girimaji
Despite widespread enthusiasm, applying artificial intelligence and machine learning (AI/ML) to
turbulence modeling has yielded only modest progress, primarily due to a lack of situation-aware deployment. Data-driven Reynolds-averaged Navier–Stokes (ML-RANS) closures frequently fail to generalize across diverse flow regimes, while scale-resolving simulations (SRS) remain computationally prohibitive. As a result, ML-RANS is often misapplied outside its domain of validity, and ML-SRS is unnecessarily deployed on flows fully amenable to RANS. To guide optimal AI/ML deployment, we propose a
turbulence taxonomy map parameterized by degrees of freedom ($Re$) and the degree of non-
equilibrium ($SK/\epsilon$). By applying Weaver's well-recognized complexity framework, we classify
turbulence into distinct physical regimes. This categorization identifies where local ML-RANS surrogates can generalize, clarifies where explicit scale resolution is physically mandatory, and highlights where physics-informed neural networks (PINNs) are most effective. Ultimately, this perspective establishes a physics-grounded framework for the flow-aware, successful deployment of AI/ML in
turbulence.
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General Relativity and Quantum Cosmology
No-Go Theorem for Phantom Crossing in Scalar-Tensor Gravity with Non-Minimal Derivative Coupling and Soft Scale-Invariance Breaking
Reza Baghbani
Recent baryon acoustic oscillation measurements from the Dark Energy Spectroscopic Instrument (DESI 2024) reveal a preference for dynamical dark energy with an equation of state parameter crossing the phantom divide ($w < -1$) at low
redshifts. We investigate whether this phantom crossing can be realized within scale-invariant scalar-tensor theories featuring non-minimal derivative coupling (NMDC) between the scalar field and the Einstein tensor. Employing the effective field theory of dark energy formalism, we systematically derive the ghost-free and gradient stability conditions, and examine their compatibility with the swampland
conjectures from
quantum gravity. We establish three rigorous no-go
theorems demonstrating that: (i)~phantom crossing necessitates $\xi_{\text{eff}} < 0$, directly violating the no-ghost stability requirement $\xi_{\text{eff}} > 0$; (ii)~the swampland de Sitter and distance
conjectures independently obstruct phantom crossing; and (iii)~these theoretical obstructions are mutually reinforcing. Our results show that scale-invariant NMDC models cannot account for the DESI preference for $w < -1$, providing robust theoretical guidance for dark energy model building beyond this class.
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High Energy Astrophysical Phenomena
The effect of triples on the Chemically Homogeneous Evolution Channel for producing Gravitational Wave Sources
Silvia A. Popa, Selma E. de Mink, Stephen Justham et al. (+3 more)
Despite the growing number of gravitational-wave (GW) detections, the formation of merging binary black holes (BBHs) is still debated. One of the proposed formation channels is Chemically Homogeneous
Evolution (CHE), which makes distinct predictions for the properties of the resulting black holes (BHs): high masses ($\gtrsim35\, M_\odot$) and large, orbitally-aligned
spins. These predictions are based on studies that consider this channel only in isolated binaries. However, most massive
stars reside in triples. We investigate how a tertiary affects the CHE channel. We use detailed binary models computed with MESA for the inner CHE systems coupled with analytical prescriptions for the hierarchical triple dynamics. Specifically, we study the von Zeipel-Lidov-Kozai mechanism that can accelerate the merger of the inner BBHs through high-eccentricity excitations. We show that a tertiary companion enables mergers at higher
metallicities, where the classical binary CHE channel does not operate. At $Z_\odot/3$, triples produce BHs with lower masses (around $15\,M_\odot$) and lower
spins (around 0.25) compared to the low-
metallicity classical scenario. We further expect triple dynamics to lead to
spin-orbit misalignment and potential residual eccentricities at merger. In triples at $Z_\odot/3$, half of the mergers occur within 1 Gyr. Moreover, 10% of the population leads to
prompt mergers within 1 Myr (1% within 1 kyr) that are of potential interest for electromagnetic counterparts. We conclude that the triple CHE channel is promising as (i) it may contribute more substantially to the local merger rate than had been expected for the classical CHE channel due to the shorter delay times and effectiveness at higher
metallicities and (ii) produces mergers with properties that more closely resemble the lower masses and lower
spins inferred for most of the observed GW merger population.
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All authors Silvia A. Popa, Selma E. de Mink, Stephen Justham, Jakob Stegmann, Alejandro Vigna-Gomez, Lieke A. C. van Son
Solar and Stellar Astrophysics
Mapping Wolf-Rayet winds with spectro-interferometry I. Detection of multiple co-rotating interaction regions in WR 6
K. Deshmukh, A.-N. Chené, A. J. Frost et al. (+8 more)
WR 6 is the prototype for periodic variability due to large-scale wind structures in Wolf-Rayet (WR)
stars, showing a consistent periodicity of 3.76 d in photometry, spectroscopy, and polarimetry. However, the origin of this variability is debated, attributed either to corotating interaction regions (CIRs) or a low-mass companion. We use time-resolved interferometry to investigate the origin of periodic variability in WR 6. We aim to detect and characterize structures in the stellar winds of WR 6 and discriminate between the CIR and low-mass companion scenarios. Using the extended configuration of the Auxiliary
Telescopes at VLTI, we obtained six
GRAVITY epochs over six months to search for the presence and variability of wind-structures in WR 6. We also obtained complementary spectroscopic observations during one of the epochs to monitor contemporaneous spectral line variability. For all six epochs of
GRAVITY observations: (i) WR 6 is consistent with a single
star and has no spatially resolved companion detected above $M\gtrsim6\,M_\odot$; (ii) The He I line-emitting region is spatially resolved, while the He II lines remain unresolved, consistent with atmosphere models; (iii) Around 2.19 $\mu$m, discrete line-emitting features offset from the center of the
star are detected. The number, positions, and wavelengths of these features vary across epochs. Spectroscopic monitoring reveals spectral line residuals that broadly correspond to the two features seen in the
GRAVITY data of the fifth epoch. Finally, the first three epochs, observed on three consecutive nights, show significant variability in these features but cannot be directly linked across epochs. We thus report the detection of multiple large-scale structures in the wind of WR 6 with VLTI/
GRAVITY. We favor CIRs as their likely origin owing to temporal and spatial variability that cannot be reconciled with a low-mass companion.
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All authors K. Deshmukh, A.-N. Chené, A. J. Frost, T. De Prins, L. Fabiani, H. Sana, R. R. Lefever, A. Mérand, N. D. Richardson, A. A. C. Sander, T. Shenar
High Energy Physics (Theory)
One-loop QED effective action at finite temperature and density beyond HTL limit
Farahmand Hasanov and Nikita Kolganov
We develop a framework for computing the nonlocal one-loop effective action in scalar and spinor QED at finite temperature and chemical potential in arbitrary even spacetime dimensions. Based on the heat kernel expansion to quadratic order in background fields, the framework reduces the effective action form factors to a common fundamental kernel. By resumming the external-momentum expansion, we obtain explicit closed-form expressions for the massless form factors in terms of polylogarithms and their derivatives with respect to the order. The same method determines the coefficients of the small-mass expansion to arbitrary order. The resulting expressions retain the full dependence on external Euclidean momentum, temperature, and chemical potential, without invoking the soft-momentum approximation. We also derive the corresponding
photon polarization operators and evaluate their static limits, obtaining the Debye screening masses and electromagnetic susceptibilities.
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Instrumentation and Methods for Astrophysics
Harmonic and intermodulation emission from direct-to-device satellites - Harmonics of the Starlink 2.6 GHz downlink and the products around them
Balthasar Indermuehle, Benjamin Winkel, Federico Di Vruno et al. (+2 more)
Direct-to-device (DTD) satellites carry mobile base stations transmitting in terrestrial mobile bands. Their non-linear emission products can fall into
radio astronomy bands, including passive bands. We measure the harmonics of the Starlink DTD downlink at 2620-2630 MHz and the intermodulation products around them, search for products next to the carriers, and compare them with the ITU-R unwanted-emission limits and
radio astronomy protection criteria. We use autocorrelations of single Australia
Telescope Compact Array
antennas on tracked passes of DTD and other satellites with the 16 cm and 4 cm receivers. Harmonic ratios and receiver tests show that the harmonics are satellite-generated. We simulate the aggregate equivalent power flux density of a constellation at Effelsberg and the ATCA. The harmonics H2 to H4 at 5240, 7860 and 10480 MHz fall by about 16 dB per order, show no trend with elevation, and originate on the satellite. H2 is also detected in 32% of integrations more than 10 degrees from any DTD satellite. Inside the harmonic zones the spectra follow the n-fold convolution of the carriers; outside them, intermodulation products of order n+2 and higher lie on average 19 dB below the zone and switch between -23 and -15 dB within seconds. Next to the carriers no satellite emission is detected to 33 dB below the carriers. H2, >=-38.9 dBW in 4 kHz isotropic-equivalent, is at or above the SM.329 space-station limit; H3 and H4 meet it. For 8640 satellites the aggregate exceeds the protection criteria by 65 and 25 dB at the second and fifth harmonics, and by >100 dB for out-of-band emission at the mask level in 2690-2700 MHz. Harmonics are received far outside the serving beams. Their radiated level must be limited directly, not through the power at the
antenna port. Compliance with per-satellite ITU-R limits does not protect
radio astronomy from the aggregate of a constellation.
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All authors Balthasar Indermuehle, Benjamin Winkel, Federico Di Vruno, Gyula Jozsa, Liroy Lourenco
Applied Physics
Optimization of Active Reconfigurable Surfaces for Spatiotemporal MU-MIMO Wave Routing in Disordered Media: Application to the Cocktail-Party Problem
Frederic J. N. Jorgensen, Florent Dorlot, Constant Bourdeloux et al. (+4 more)
We design an active reconfigurable intelligent surface (RIS) for acoustic multi-user multiple-input multiple-output (MU-
MIMO) communication by solving a large-scale convex optimization problem, so that each emitter's broadband signal focuses in space and time at its intended receivers while crosstalk is suppressed. In acoustic experiments, we show that our approach outperforms existing time-reversal methods by 5.1-7.6 dB in crosstalk suppression, while achieving better temporal focusing.
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All authors Frederic J. N. Jorgensen, Florent Dorlot, Constant Bourdeloux, Mathias Fink, Fabrice Lemoult, Steven G. Johnson, Raphaël Pestourie
Mathematical Physics
Inverse Resonance Problem for the Half-Line Schrödinger Operator with a Complex Robin Boundary Condition
Roman Shterenberg
We study the inverse resonance problem for the one-dimensional Schrödinger operator on the half-line with a compactly supported complex-valued potential and a complex Robin boundary condition \[ u'(0)-a u(0)=0,\qquad a\in\mathbb C. \] The proof follows the transformation-operator, entire-function, and
Fourier analytic strategy developed by Marletta, Shterenberg and Weikard for the Dirichlet problem \cite{MSW}. The Dirichlet Jost function $\psi(z,0)$ is replaced by the Robin characteristic function \[ F_a(z;q)=\psi_x(z,0;q)-a\psi(z,0;q). \] We establish the corresponding large-energy estimates, Hadamard factorization, finite-data stability, and uniqueness results. The principal new feature is that $F_a(z;q)=iz-a+O(1)$ rather than $1+O(z^{-1})$. In the transformation-operator argument the relevant boundary quantity is $B_x(0,t)-aB(0,t)$, together with the scalar term $B(0,0)$. For fixed $a\in\mathbb C$, and uniformly for $a$ in bounded subsets of $\mathbb C$, the resulting inverse resonance estimates have the same qualitative form as those proved in \cite{MSW} for the Dirichlet problem. In particular, for a fixed Robin parameter $a$, the complete set of Robin
eigenvalues and resonances, counted with multiplicity, determines the potential uniquely. The text is produced with the help of AI ChatGPT for Academy.
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Materials Science
A Solution-Processed Ti/Pt/NiOx/Ag RRAM Device with Multiple Forming-Free Non-Volatile Intermediate States
Abhrajit Roy, Chopali Chanchal Sahu, Rudraksh Sangore et al. (+5 more)
Artificial neural networks (ANN) implemented on crossbar arrays of non-volatile synaptic devices are known to consume much less energy compared to that implemented on conventional computing units. Solution-processed resistive random-access
memory (RRAM) devices based on transition-metal oxides are suitable as such synaptic devices because of their cheap and easy fabrication method, stability, and suitable memristive properties. Here, in NiO-based RRAM devices with Ti/Pt as the bottom electrode and Ag as the top electrode (NiO layer deposited through solution processing), we experimentally report forming-free binary switching between a high resistance state (HRS) and a low resistance state (LRS) as well as forming-free pulse-driven modulation (long-term potentiation (LTP), long-term depression (LTD)) through 30 intermediate synaptic states between HRS and LRS (around 5-bit synaptic weight resolution). Many of these states are measured to be stable at least up to 1000 seconds confirming their non-
volatility and their utility in storage of synaptic weights for ANN crossbar arrays. On the contrary, most prior experimental reports (including reports both on solution-processing-based and sputtering-based RRAM devices) require forming to exhibit non-
volatility. Avoiding forming reduces variability, eliminates the need for high voltage pulses, and makes the crossbar array design simpler. Further, we confirm the presence of oxygen vacancies in our materials stack using X-ray photo-electron spectroscopy (XPS). Finally, we show successful data classification on MNIST and CIFAR-10 data sets using a multi-layer perceptron (MLP) model and a convolution neural network (CNN) model respectively, where the synaptic weight updates of these ANN models are calibrated against the experimentally measured LTP-LTD characteristics of the NiO RRAM devices.
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All authors Abhrajit Roy, Chopali Chanchal Sahu, Rudraksh Sangore, Raman Hissariya, Poulomi Chakrabarty, Harsh Roniyar, Merlyne De Souza, Debanjan Bhowmik
Fluid Dynamics
Finding a reconnection in a vortex-haystack
Abhishek Harikrishnan, Benjamin Musci, Adrien Lopez et al. (+8 more)
Counter-rotating
vortex reconnection is a
topology-transforming event that leads to strong vorticity amplification and is often associated with the most irregular regions of the velocity field. Detecting such events directly in turbulent flows is a major challenge due to the ambiguity inherent in the definition of a
vortex and the rapid proliferation of intense small scale
vortices. We develop a novel methodology by combining two tools. The first is a local in scale, space and time regularity indicator that isolates spatio-temporal regions of interest. The second is a reconnection indicator that exploits a well-known property of
vortex reconnection namely, that the enstrophy (volume integral of the square of vorticity) flows from the
symmetry to the collision plane. To examine the flow of enstrophy in the correct reference frame, a new method inspired by orientational order parameters in
liquid crystals is developed. We then show a proof of concept for our reconnection indicator by comparing it with diagnostic methods available in the literature. The method is validated on experimental
datasets from a turbulent von Kármán flow at two different resolutions, one of which allows us to probe the flow below the Kolmogorov scale, $\eta$. Our findings suggest that counter-rotating
vortex reconnection could be a potential mechanism for the creation of motions at scales below $\eta$.
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All authors Abhishek Harikrishnan, Benjamin Musci, Adrien Lopez, Bartosz Protas, Adam Cheminet, Jean Le Bris, Jean-Marc Foucaut, Jean-Philippe Laval, Christophe Cuvier, Pierre Bragança, Bérengère Dubrulle
Optics
Fast local field calculation in cascaded coupled systems
Isam Ben Soltane, Romain Asso and Matthieu Davy
Computing the field within a sub-unit of cascaded systems is a recurring problem in wave physics. It is central to gradient-based inverse design, in situations where only a region of the system is modified while the rest remains fixed. Standard approaches either resimulate the entire cascade at every change, or require a detailed characterization of every surrounding sub-system. Both become impractical when many design iterations are needed. Here, we introduce a hybrid method combining the $S$-
matrix approach, which propagates fields through cascaded systems, with the Green's function method, which gives the field generated by a source within a characterized system. In this approach, the sub-systems surrounding the region of interest need only be characterized once, after which the local field can be recomputed rapidly for any new configuration. We validate the method on a disordered lossy waveguide, finding excellent agreement with finite-element simulations. We also demonstrate its efficiency on a disordered multimode cavity, where it achieves a fifty-fold speed-up over full-wave simulation and reduces a wideband focusing calculation from eleven hours to ten minutes. This approach opens the way to fast, iterative field calculations in complex systems coupled to their environment, with direct applications to inverse design and wideband wavefront-shaping.
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High Energy Physics (Theory)
Three-dimensional vacua of $G_2$ flux compactifications
Aravind Aikot, Julian Choi and Timm Wrase
We study supersymmetric
vacua of three-dimensional $\mathcal N=1$ effective theories from type IIA, type IIB/type I, and heterotic compactifications on $G_2$-structure spaces. Superpotential homogeneity and the physical scalar metric yield universal
vacuum relations and
axion stabilization constraints without specifying the full moduli-space metric. We express AdS$_3$ scalar masses through $\Delta$, the scaling dimension of the corresponding operator in the dual two-dimensional conformal field theory. In massive type IIA AdS$_3$
vacua, we derive the bound $\Delta_{\max}\geq(20+4\sqrt{67})/7\approx 7.5$ and an exact dimension $\Delta_b=6$ for $B_2$
axions on the torsion-free branch. Type IIB type I and heterotic AdS$_3$
vacua contain a universal volume-dilaton mode with $\Delta_{\phi s}=4$. On the singlet-torsion type IIB branch, we also obtain the volume-dilaton mode with $\Delta_{\phi s}=20/7$ and $\Delta_b=16/7$. Every supersymmetric Minkowski
vacuum in the retained classical closed-string theories possesses an exact volume-dilaton flat direction. We characterize physical large-flux limits after tadpole constraints and axionic identifications, and identify torsion obstructions to isotropic scale separation.
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Nuclear Theory
Competitive constraints on exotic tensor currents from $EC/\beta^+$ ratios
Victor Dumenil and Leendert Hayen
We introduce the ratio of electron capture to positron decay rates of unstable
nuclei as a probe for exotic tensor currents in the electroweak sector. We calculate nuclear structure corrections and newly derived radiative corrections and obtain competitive limits on exotic tensor couplings using historically available data to find $\varepsilon_T = (1.06 \pm 0.76)\times 10^{-3}$ which is competitive with
collider searches and the global $\beta$-decay database. In doing so, we resolve a 50-year-old tension in the strongly hindered $^{22}$Na transition by retaining higher-order operators, obtaining a consistent description of its different weak-decay observables. Finally, we discuss the potential of this method to significantly improve tensor constraints using modern cryogenic
quantum sensors.
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Physics Education
Characterizing adopters of named active learning methods in physics: An interview study
Ibukunoluwa Bukola, Eric Brewe, Adrienne L. Traxler et al. (+1 more)
Active learning has been shown to be more beneficial for student learning than lecturing. Consequently, researchers have developed named active learning strategies for use in physics instruction. To increase adoption and support implementation of these named methods, it is important to understand the backgrounds and experiences of instructors who use them. In this study, we interviewed 20 introductory physics and astronomy instructors who use one of Student-Centered Active Learning Environment with Upside-Down Pedagogies (SCALE-UP), Investigative Science Learning Environment (ISLE), Tutorials in Introductory Physics and Astronomy, or Peer Instruction to gain insight into their teaching experiences, professional development, pathways to learning about their method, and supports for and difficulties in implementation. We find for our sample that all implementers are involved with the discipline-based education research community, but there is variation in the extent of engagement. While instructors identify a variety of supports for their implementation, such as from the broader education community and departmental administration, the difficulties they experience are representative of both long-standing issues associated with active learning adoption (e.g., timing constraints) and new issues related to emergent technologies (e.g., Artificial Intelligence). Finally, we uncover differences in implementers across the four named methods, particularly related to their training for the method and the supports they received for implementation. Together, these findings underscore the importance of supporting multiple dissemination avenues for named active learning methods, point to a possible need for more training opportunities for SCALE-UP and ISLE in particular, and identify nascent issues in the contemporary active learning classroom that future work may further characterize and address.
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All authors Ibukunoluwa Bukola, Eric Brewe, Adrienne L. Traxler, Meagan Sundstrom
Accelerator Physics
AI Acceleration of Muon Collider R&D: A Report from the AI4MuC Workshop
J. Scott Berg, David Bizzozero, Tulika Bose et al. (+27 more)
A
Muon Collider is one of the most attractive routes to multi-TeV lepton collisions, but it requires the accelerator and detector communities to solve a tightly coupled set of problems that have no close precedent in an operating
collider.
Muons must be produced, captured, cooled, accelerated, and collided before they decay. The detector must then extract clean physics from an environment dominated by decay products from the beamline. Artificial intelligence is not a substitute for accelerator physics, detector design, or engineering validation. It is, however, unusually well matched to several of the central obstacles: high-dimensional design spaces, expensive simulations, coupled subsystem trade-offs, and workflows that are currently too slow or too fragile to support broad design exploration. This report distills the AI4MuC workshop into a summary of AI use cases with the potential to change the pace of
Muon Collider R&D, organized around the following physics bottlenecks:
muon production and capture, ionization cooling, magnet and RF technology, detector design in beam-induced background, background simulation and generation, reconstruction, and software.
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All authors J. Scott Berg, David Bizzozero, Tulika Bose, Lance Cooley, John Dervan, Auralee Edelen, Peter Elmer, Cristiano Fanelli, Tova Holmes, Walter Hopkins, Sergo Jindariani, Michael Kagan, Maira Khan, Young-Kee Kim, Matt LeBlanc, Lawrence Lee, Matthias Liepe, Radha Mastandrea, Patrick Meade, Federico Meloni, Chad Mitchell, Linh Nguyen, Isobel Ojalvo, Ryan Roberts, Nicholas Smith, Jean-Luc Vay, Gordon Watts, Drew Winder, Chenran Xu, Katsuya Yonehara
Other Condensed Matter
Revealing New Leakage Paths in GAAFETs using Predictive First-Principles Simulations
Denis Mamaluy, Juan P. Mendez, Coleman Cariker et al. (+2 more)
Gate-All-Around Field-Effect Transistors (GAAFETs) are emerging as successors to Fin Field-Effect Transistors (FinFETs) and are central to continued scaling at advanced
semiconductor nodes. Despite their improved electrostatic control, recent measurements show that the drain current in GAAFETs deviates strongly from thermionic behavior at negative gate voltages, increasing as the gate voltage becomes more negative. This leakage has been attributed to direct gate-drain tunneling through the high-$k$ dielectric, enhanced by drain-induced dielectric barrier lowering (DIDBL). Here, we use predictive, charge-self-consistent Non-
Equilibrium Green Function (NEGF) simulations based on the Contact Block Reduction (CBR) method to spatially resolve this leakage pathway in GAAFETs. Unlike approaches based primarily on phenomenological leakage models, our first-principles, multi-terminal
quantum-transport framework treats the source, drain, and gate as current-carrying
quantum-mechanical contacts and resolves the local current density throughout the device. The spatially resolved current density shows that gate-injected carriers tunnel through the high-$k$ dielectric preferentially near the drain side of the gate, where the dielectric barrier is most strongly lowered by the drain bias, and are collected by the drain. This provides a direct real-space picture of the DIDBL-driven gate-drain leakage mechanism.
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All authors Denis Mamaluy, Juan P. Mendez, Coleman Cariker, Michael Titze, Alex A. Belianinov
Optics
Definition of Multi-Parameter Super-Resolution for Optical Telescopes
Peter Menart, Seungman Choi and Zubin Jacob
Super-resolution techniques in microscopy are opening new frontiers in biology, and super-resolution for
telescope imaging may provide similar benefits for astronomy and space domain awareness.
Telescope super-resolution techniques such as multi-plane light conversion and photonic lanterns have been inspired by the ability of mode sorting measurements to extract classical Fisher information closer to the
quantum bound than standard
telescope imaging. Fisher information analyses for super-resolution imaging systems commonly consider the case of imaging point sources, but often only consider estimating a small subset of the parameters. Furthermore, there has been no demonstration of an estimation
algorithm with performance that follows the limit set by the Fisher information when all point source parameters are considered. We provide a framework for defining and analyzing super-resolution using the classical and
quantum Fisher information for the multi-parameter estimation problem and demonstrate an
algorithm that can achieve the classical Fisher information bound for all the parameters simultaneously.
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High Energy Physics (Theory)
The dimensional reduction of the spin-3 and spin-4 partially broken Fronsdal models
D. Dalmazi and A. L. R. dos Santos
Here we perform a Kaluza-Klein dimensional reduction from $D+1$ to $D$ dimensions of a partially broken Fronsdal model for
spin-3 and
spin-4. The reduced models describe massive
spin-3 and
spin-4 particles without extra propagating modes. They differ from Singh-Hagen models by quadratic terms which vanish on shell, similarly to their higher dimensional massless parents. A covariant description of the reduced models in terms of gauge invariant field combinations naturally leads to higher derivative models, contrary to lower
spin cases ($s\le 2$). For both $s=3$ and $s=4$ we have a rather peculiar massless limit. Although their particle content corresponds to the $\pm j$ helicities with $j=0,1, \cdots s$, as expected, they appear intertwined in a non trivial way preventing diagonalization through any local field redefinition.
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Solar and Stellar Astrophysics
What does self-supervision add to engineered features for stellar light curves?
Zijun Liu, Yue Ma and Christopher A. Theissen
TESS light curves encode a
star's pulsation, rotation, binarity and oscillations, among other physical properties, but the survey produces far more light curves than can be labelled by hand. Astronomers have engineered a few dozen physically motivated features from them, which together remain a strong baseline. Previous work has trained encoders on light curves and judged them by their own downstream scores, but has not asked what they add to the engineered features. We pre-train a convolutional encoder on unlabelled TESS light curves to predict each window's latent representation from those of its neighbours. We then freeze it, add its features to the 25 engineered features, and read the combination out with one fixed linear probe on ten tasks: five variability classes, four asteroseismic targets and rotation period. Adding the learned features improves the readout on 7 of 10 tasks over the engineered features alone, where an untrained encoder does not. The combination also outperforms two networks trained end-to-end on the same labelled
stars on most tasks. An encoder trained without labels therefore gives astronomers new features that complement the ones they already use rather than replace them.
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Mathematical Physics · Cross-listed from math.DS
Example of exponential many collisions of identical hard disks in the plane
Hongda Qiu
Let $ \operatorname{MaxCol}(n,d) $ denote the maximal number of nonsimultaneous elastic collisions among $n$ identical hard balls moving freely in $\mathbb{R}^d$. We give a planar construction with exponential lower bound with respect to $n$: $ \operatorname{MaxCol}(n,2)\geq 2^{\lfloor n/2\rfloor}, \quad n\geq3 $.
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