Applied Physics
DDSNet: Dual-domain Symmetry-aware Network for PCSEL Property Prediction
Cen Chen, Haitao Huang, Jiazhi Mao et al. (+3 more)
Efficient exploration of the photonic
crystal (PhC)
lattice design space is essential for developing photonic
crystal surface-emitting
lasers. While coupled-wave theory (CWT) provides an effective physical framework, its computational cost remains prohibitive for large-scale exploration, driving the demand for neural surrogates. However, existing AI models underexploit two key factors of PhC unit-
cell dielectric patterns indicated by CWT: spectral components and asymmetric structures, which largely govern devices' physical properties. This mismatch weakens surrogate accuracy and screening reliability, especially in structure-sensitive regions. To address this, we propose the Dual-Domain
Symmetry-Aware Network (DDSNet). It integrates translation-equivariant spectral filtering with a
symmetry-induced structural prior. The spectral filtering injects a spectral inductive bias into
vision model while preserving translation equivariance on
lattices. Meanwhile, the structural prior decomposes
lattice features into irreducible representation-associated,
symmetry-resolved components and processes them in separate branches. Experiments demonstrate that DDSNet significantly outperforms existing AI baselines in property prediction and high-throughput screening, exhibiting superior reliability in structure-sensitive regions. Crucially, component masking analyses reveal that the network successfully learns property-specific dependencies aligned with physical priors. These results indicate that DDSNet effectively captures physically meaningful structure-property relationships, establishing a highly reliable neural surrogate for PhC design space exploration.
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All authors Cen Chen, Haitao Huang, Jiazhi Mao, Feifan Xu, Zhe Zhuang, Yuxiang Ren
General Physics
Effective de Sitter-Schwarzschild Metrics
Moorad Alexanian
An earlier work that replaced the de Sitter-Schwarzschild metric for a cosmological constant Lambda <=0 by an effective anti-de Sitter black hole analytic at Lambda = 0 is here extended to the horizon structure through its three possible roots. We replace the de Sitter-Schwarzschild metric for all possible values of Lambda and the Schwarzschild radius R for the three possible available roots by either a Schwarzschild black hole whose radius depends on both R and Lambda or a de Sitter space whose cosmological constant depends on both R and Lambda.
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Instrumentation and Detectors
Tunable Light Scattering in Cast Organic Scintillators via BaSO$_4$ Nanoparticle Doping: A Short Summary
H. G. Zaunick, R. Bergert, K. T. Brinkmann et al. (+9 more)
We summarize the fabrication and optical characterization of small-format (2 x 2 x 2 cm$^3$) cast organic scintillators based on Eljen EJ-290 resin, doped with barium sulfate (BaSO$_4$) powder at mass fractions from 0 % to 5 %. The goal is to tune the scattering length of the scintillator largely independently of its absorption and light output, so that scintillation light is localized on a controllable spatial scale matched to the fiber pitch of wavelength-shifting (WLS) fiber read-out. The scattering length is found to decrease from 6.05(8) cm at 1 % to 0.83(1) cm at 5 %, while the absolute light yield falls by only about 15 %. These results are a first proof of concept that the
photon-transport scale in cast scintillators can be engineered on purpose, enabling position-sensitive scintillator tiles for fiber-readout sampling calorimeters and large-area
muon trackers. Full details are given in the accompanying paper.
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All authors H. G. Zaunick, R. Bergert, K. T. Brinkmann, V. Dormenev, K. Eichhorn, J. M. Friedrich, S. Glennemeier-Marke, D. Kazlou, H. Lacker, M. J. Losekamm, C. Scharf, I. M. Wöstheinrich
Atomic Physics · Cross-listed from quant-ph
Bright-state source cancellation in dissipative shortcut Raman atom optics
Asad Ali, Saif Al-Kuwari, M. I. Hussain et al. (+3 more)
Spontaneous Raman scattering limits shortcut-assisted atom optics, but its microscopic origin is obscured once the lossy excited state is adiabatically eliminated. We organize the problem around a single quantity: in the instantaneous dark-bright basis the lower-
manifold optical source is carried entirely by the bright-state amplitude, $S=\Omega b$, so that primary spontaneous scattering reduces to the compact functional. This recovers the known dissipative-STIRAP loss in transparent form and makes the action of a shortcut explicit: ideal counterdiabatic STIRSAP cancels the bright-state source, not the optical decay coefficient. We show this cancellation is exact in the full three-level model at the counterdiabatic point, for arbitrary one-
photon detuning, Rabi frequency, and pulse duration. The residual source splits into orthogonal quadratures – shortcut mismatch (real) and two-
photon Doppler detuning (imaginary) – which invites a velocity-selective protocol that nulls the Doppler quadrature for a chosen momentum class with a second, phase-shifted lower-state field. Our central result is that this source nulling is never superior to simply chirping the two-
photon detuning: the two coincide only when the selected class $\delta_c$ is small compared with the bright-state gap, and the nulling degrades and then fails as $\delta_c\to|\mu|$ – precisely the regime of launched or warm clouds and high-order large-momentum-transfer (LMT) optics that motivates velocity selection. The controlling quantity is the magnitude of the residual
Hamiltonian perturbation a scheme leaves behind, not the residual source it cancels. As a complement to existing multi-pulse decay budgets, we cast a single-pulse mode-error budget for LMT interferometry entirely in terms of the bright-state source, and delineate when shortcut-assisted Raman control reduces the total scattering cost.
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All authors Asad Ali, Saif Al-Kuwari, M. I. Hussain, H. Kuniyil, M. T. Rahim, Saeed Haddadi
Fluid Dynamics
Effects of mean flow skew on turbulent shear layers. Part I. Numerical investigation
Vedant Kumar, Dipendra Gupta, Gregory Paul Bewley et al. (+1 more)
Skewed turbulent shear layers, formed by the interaction between two non-aligned turbulent boundary layers, are investigated using high-fidelity large eddy simulations in a temporally evolving framework. It is argued that a skewed shear layer of this form should be viewed, in the long-time limit, in a rotated reference frame as the superposition of a standard planar shear layer and an orthogonal jet-like component that decays in time. The skewed shear layer is found to have reduced vertical integral length scale, and the coherent pressure rollers characteristic of shear layers undergo transient realignment towards the direction orthogonal to mean shear, consistent with the long-time limiting planar shear layer. Numerical experiments using fictitious test cases indicate that these effects are primarily driven through misalignment in the mean flow, and that the two orthogonal flow components in the mean shear frame are only weakly coupled.
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All authors Vedant Kumar, Dipendra Gupta, Gregory Paul Bewley, Johan Larsson
Optics · Cross-listed from quant-ph
Picosecond Schrödinger cat states for ultrafast optical quantum processing
Mamoru Endo, Kan Takase, Takefumi Nomura et al. (+12 more)
Non-Gaussian states are essential resources for universal, fault-tolerant optical
quantum computing, but their generation rate remains limited by low heralding probabilities and operation in nanosecond temporal modes. Here, we demonstrate multi-
photon generalized
photon subtraction in picosecond optical wave packets, establishing the state-generation capability required for high-rate operation by addressing the temporal-mode bottleneck that has constrained the achievable rate. Two interfering ultrashort squeezed
vacua are heralded by
photon-number-resolving detection with a high-speed transition-edge sensor and characterized by pulsed homodyne detection matched to 10-ps temporal modes at a 5-MHz pump repetition rate. We reconstruct Wigner functions without loss correction that exhibit up to four distinct negative regions for four-
photon heralding, together with an effective cat-state amplitude of $\alpha_{\mathrm{eff}} = 1.69$. This amplitude approaches the range of practical relevance for fault-tolerant cat-code architectures and for adaptive breeding toward logical-
qubit generation, while the picosecond temporal mode establishes a platform compatible with high-rate, scalable time-multiplexed photonic architectures.
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All authors Mamoru Endo, Kan Takase, Takefumi Nomura, Tatsuki Sonoyama, Kazuma Takahashi, Sachiko Takasu, Daiji Fukuda, Takahiro Kashiwazaki, Asuka Inoue, Takeshi Umeki, Peter van Loock, Petr Marek, Radim Filip, Warit Asavanant, Akira Furusawa
Optics
Attenuation scaling and error analysis of 2f and 4f architectures for free-space optical matrix-vector multiplication
Dawson Lyles and Spencer LaVere Smith
Free-space optical computing has been suggested as a scalable, high speed, and energy efficient platform for performing
matrix-vector multiplication (MVM). We present two free-space optical approaches for MVM, called the 2f and 4f architectures, and model them using wave optics simulations. After constraining the optical modulator in our models to have a maximum gain limit, we use our simulations to compare 2f and 4f MVM performance in terms of computational error and optical signal attenuation per MVM. We examine how 2f and 4f signal attenuation per MVM scales with increasing MVM problem size for different statistical distributions of
matrix elements and compare to the expected attenuation from a universal multiport interferometer (UMI), commonly used in integrated photonics for MVM. We find that the 2f and 4f architectures scale more favorably to large problem sizes, experiencing many orders of magnitude less attenuation than UMIs for
matrix dimension above a thousand elements. We furthermore examine how varying modulator space-bandwidth product and output slit aperture affect 2f and 4f attenuation and computational error across different distributions of
matrix elements. We conclude that the preference of 2f or 4f MVM depends on the statistics of the
matrix used, but that 4f may provide more flexibility than 2f.
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Biological Physics · Cross-listed from math.NA
Diagonal Frog: High-order positivity-preserving FD schemes for anisotropic Fokker-Planck equations
Andrey Itkin
The Fokker-Planck equation is fundamental to statistical mechanics, yet in settings with multiple state variables, anisotropic (cross-)
diffusion, and jumps, conventional discretizations frequently produce non-physical negative probability densities. Building on the operator approach of "A. Itkin, Pricing derivatives under Levy models. Modern finite difference and pseudo-differential operators approach, Springer, 2017, ISBN 978-1-4939-6792-6", we introduce a family of "Diagonal Frog" discretizations whose spatial operators are eventually M-
matrices (EM-
matrices). Although these operators lack a local M-
matrix structure, positivity of the directional sub-operators emerges in the spirit of Zeno's paradox: the
matrix exponential, assembled as the limit of infinitely many ever-smaller substeps, is provably nonnegative after a short transient even though no single substep is. For the mixed-derivative block, whose generator is not eventually nonnegative, positivity instead rests on a factorized resolvent solver and holds conditionally, on an explicit step-size window; discrete mass is conserved exactly by the splitting for every step size. The resulting schemes are second-order accurate in time and space and require O(m 2 N + m 3) operations per time step, where m is the dimension of the Krylov subspace used to apply the exponential. As stress tests, we solve a two-dimensional anisotropic Fokker-Planck equation in the strong cross-
diffusion regime against an exact Gaussian reference, a Kramers escape problem in a double-well potential, and an advection-dominated problem, and observe that the schemes remain stable, nonnegative, and mass-conservative for a wide range of Pécklet numbers (so, don't need any flux limiter). Finally, we extend the construction to multidimensional processes and to the backward Kolmogorov equation with jumps.
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Plasma Physics
The science of compressional heating on the LM26 magnetized target fusion experiment
S. J. Howard, D. P. Brennan, K. Epp et al. (+61 more)
The Lawson Machine 26 (LM26) at General Fusion has demonstrated compressional heating of a spherical tokamak deuterium
plasma as it was compressed by an imploding solid lithium liner. Results from the first 11 compression shots on LM26 are presented, the highest-performing of which show more than a 3x increase in $T_e$, a 10x increase in $n_e$, and a 10x increase in $B_{pol}$ within the
plasma driven by 3x radial compression. The experimental device and instrumentation are reviewed in detail, followed by observations about the liner trajectory and
evolution of
plasma properties, including increases in emission of
neutrons, X-rays, and visible radiation. Observations from fast-camera images during compression provide context for interpreting the spatial structure of
plasma-wall interaction. Overviews of relevant models and analysis are presented. Diagnostic data are used to reconstruct the experimental
equilibrium state in computational framework as a function of time. The results build confidence in the stability and transport analyses that support the primary conclusions. Trends across the full set of 11 compression shots are presented, and detailed examinations of the high-performance shots are given individually. The central conclusions of the integrated physics model specifically indicate that compressional heating was achieved in this set of experiments, as evidenced by the balance of heating power from compression, Ohmic heating from
plasma current, and losses to the boundary needed to match the experimental data. A majority of the temperature rise is attributable to compressional heating. An increase in
neutron flux is also observed during compression. The results provide a basis for planned improvements to the LM26 facility that will enable the compression of magnetized
plasma to increasingly higher densities and temperatures.
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All authors S. J. Howard, D. P. Brennan, K. Epp, P. Forysinski, D. Plant, M. Reynolds, A. Froese, N. Sirmas, D. Krotez, V. Suponitsky, R. Zindler, E. Love, C. Macdonald, N. Kumar, Z. Seifollahi Moghadam, K. Conquergood, A. Wong, W. Zawalski, B. Rablah, W. Kozicki, P. Carle, A. Rohollahi, C. Preston, A. M. D. Lee, J. Hobbis, L. Santos, X. Feng, M. Schellenberg-Beaver, R. Tingley, R. Underwood, J. Sanchez Rojo, J. Gorenstein, D. Froese, E. Cessford, J. Pratt, J. Crofts, J. Sardari, G. Faust, D. Ross, J. Wilkie, S. Bernard, S. Edwards, R. Oosterom, M. Yurkiv, J. Y. J. Cheng, C. Connor, S. Bolanos, C. Gutjahr, E. Chan, M. Greenwood, E. Ng, A. Massey, K. Chen, R. Svihra, A. Gromer, S. Lee, X. Zhu, L. Marshall, C. Eyrich, A. Mahoney, M. Davidson, H. Feng, A. Rudy, M. Laberge
Instrumentation and Detectors · Cross-listed from nucl-ex
Measurements of Bremsstrahlung-Averaged Cross Sections for Reactions on Natural Nickel Targets at Eendpoint = 40MeV
O. Nusair, N. Solomon, M. Toro-Gonzalez et al. (+1 more)
Bremsstrahlung activation measurements were performed to study the production of $^{57}\mathrm{Ni}$, $^{56}\mathrm{Ni}$, $^{58}\mathrm{Co}$, $^{57}\mathrm{Co}$, $^{56}\mathrm{Co}$, and $^{55}\mathrm{Co}$ from natural nickel targets irradiated with
photons generated by \SI{40}{MeV} electrons incident on a tantalum converter. Bremsstrahlung spectra were modeled using MCNP6.3\texttrademark{} and experimentally validated through activation of natural tin. Bremsstrahlung-averaged cross sections were extracted from end-of-irradiation activities, yielding $\langle\sigma\rangle = 8.983~\pm~0.028$~mb for $^{58}\mathrm{Ni}(\gamma,n)^{57}\mathrm{Ni}$, $0.248~\pm~0.025$~mb for $^{58}\mathrm{Ni}(\gamma,2n)^{56}\mathrm{Ni}$, $0.704~\pm~0.218$~mb for $^{nat}\mathrm{Ni}(\gamma,pxn)^{58}\mathrm{Co}$, $9.192~\pm~0.386$~mb for $^{58}\mathrm{Ni}(\gamma,p)^{57}\mathrm{Co}$, and $2.239~\pm~0.355$~mb for $^{58}\mathrm{Ni}(\gamma,pn)^{56}\mathrm{Co}$. A $90\%$ confidence-level upper limit of $\langle\sigma\rangle < 0.021$~mb is established for the $^{58}\mathrm{Ni}(\gamma,p2n)^{55}\mathrm{Co}$ channel. Comparison with JENDL-5 evaluations and prior studies indicates channel-dependent agreement, with residual discrepancies observed for selected charged-particle emission reactions. In particular, the measured $^{58}\mathrm{Ni}(\gamma,p)^{57}\mathrm{Co}$ cross section exceeds the JENDL-5 prediction by approximately a factor of two, whereas TALYS-2.2 calculations reproduce the experimental value, suggesting an underestimation of the $(\gamma,p)$ channel strength in JENDL-5 under bremsstrahlung conditions. For the $^{58}\mathrm{Ni}(\gamma,pn)^{56}\mathrm{Co}$ channel, both TALYS-2.2 and JENDL-5 predictions are in reasonable agreement, while the present measurement is higher by approximately a factor of two, though with larger associated uncertainty.
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All authors O. Nusair, N. Solomon, M. Toro-Gonzalez, D. DeVries
Optics
Single-Shot Realization of 10000-Mode Octave-Spanning Artificial Gauge Fields
Lida Xu, Apurva Padhye, Supratik Sarkar et al. (+6 more)
Artificial gauge fields (AGFs) enable
photons and other
bosons to emulate fermionic phenomena such as
chiral edge transport and
quantum Hall phases; however, existing theories and realizations remain confined to narrow bandwidths under single-mode approximation. We introduce a general theoretical framework for ultra-broadband, multi-modal dispersion-corrected AGFs in both linear and nonlinear regimes. Using integrated photonics, we realize over 100 distinct AGFs hosting more than 10,000 modes across nearly an optical octave – the first frequency-comb realization of the integer
quantum Hall model for
photons. Leveraging Kerr nonlinearity, we achieve single-shot AGF control beyond waveguide dispersion, robust to wafer-scale fabrication variations. Our results establish a new regime of ultra-broadband
multimodal AGFs, opening pathways to exotic dispersion-corrected AGF dynamics and simulations, as well as volume-manufacturable device functionalities such as waveguide-dispersion-resilient photonic
circuits, and AGF-enabled programmable nonlinear and
quantum optics and optoelectrics.
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All authors Lida Xu, Apurva Padhye, Supratik Sarkar, Alireza Parhizkar, Christopher J. Flower, Gregory Moille, Kartik Srinivasan, Mohammad Hafezi, Mahmoud Jalali Mehrabad
Atomic Physics
Dual-isotope narrow-line MOT of dysprosium by phase modulation
M. Dürbeck, L. Reihs, J. Seifert et al. (+6 more)
We report on the characterization of a narrow-line magneto-optical trap (MOT), where two different isotopes of the dysprosium (Dy) atom can be simultaneously loaded and trapped. We rely on phase modulation via high-power, free-space electro-optic modulators (EOMs) to generate optical sidebands at the correct detuning for two different isotopes. This technique is applied on the slowing transition at 421 nm and the MOT transition at 626 nm. Using modular resonant electronic
circuits, we match the sideband separation to the isotope shift among the two target isotopes, realizing mixtures of the bosonic isotopes 164Dy -162Dy and 162Dy -160Dy. We exploit the interplay between radiation forces and
gravity in the narrow-line MOT to control the spatial position of the two isotopes with the EOM drive frequency. We demonstrate full control of the isotopic mixture with the EOM drive, offering new and cost-effective capabilities for controlling mixtures of atomic species that can be trapped in a narrow-line MOT.
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All authors M. Dürbeck, L. Reihs, J. Seifert, B. Choudhari, J.P. Marulanda-Serna, N. Werum, M. De Pas, G. Meijer, G. Valtolina
Plasma Physics
Atmospheric carbon-14 production from neutron leakage in fusion energy systems
Brian James Albright and James Alastair Mercer-Smith
Neutron-producing fusion systems can generate atmospheric carbon-14 when
neutrons leak into nitrogen-containing gas. We use MCNP6.2
neutron-transport calculations to estimate the probability that leaked
neutrons produce $^{14}$C through $^{14}$N$(n,p)^{14}$C under representative near-ground conditions. For 14.1 MeV deuterium-tritium source
neutrons, the conversion probability is 0.25-0.50 across the geometries studied; softer leakage spectra can give larger yields. Scaling this response to a 1 GWe fusion plant shows that percent-level
neutron leakage into air would produce an atmospheric $^{14}$C source within a factor of a few of natural global production. At a 2500 GWe fleet scale, limiting fusion-derived radiocarbon to 10% of the natural source implies a mean atmospheric leakage fraction of order $10^{-6}$. These results provide a screening-level source-term estimate for atmospheric $^{14}$C production from terminal
neutron leakage in
neutron-producing fusion systems, with particular relevance to architectures containing open ports, beamlines, ducts, or other streaming paths.
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Plasma Physics
Design of a Doppler backscattering diagnostic for the Wisconsin HTS Axisymmetric Mirror (WHAM)
E. Wikarta, U. Kumar, V.H. Hall-Chen et al. (+5 more)
The Wisconsin HTS Axisymmetric Mirror (WHAM) is a compact high-field
magnetic mirror. In such
magnetic mirrors, cross-field transport is dominated by the flute instability (Endrizzi et al., 2023). To investigate density fluctuations associated with the flute instability, we designed a Doppler backscattering (DBS) diagnostic for WHAM, to be installed at the midplane port window. The diagnostic uses a two-channel tunable Ka-band (26.5–40 GHz) source and X-mode polarization. The azimuthal launch angle is set mechanically by rotating the external quasioptical assembly. As such, the system is reconfigurable during dedicated setup periods. Using the Scotty beam-tracing code (
Hall-Chen et al., 2022), we show that the proposed DBS system can measure density fluctuations with perpendicular wavenumbers $1 \leq k_\perp \leq 3~\mathrm{cm}^{-1}$ over radial locations $0.7 \leq \rho \leq 0.9$, where $\rho$ is the normalized radial coordinate. This is achieved with probe frequencies between 28 and 38.5 GHz, an elevation launch angle of $0^\circ$, and azimuthal launch angles in the range $1^\circ$–$3^\circ$. The selected configurations have low mismatch angle at cutoff, $|\theta_{m,c}|<1^\circ$. The quasioptical system uses a Ka-band horn and a biconvex ultra-high molecular weight polyethylene lens, and satisfies the port-access constraints in WHAM. The planned microwave system has a monostatic, homodyne architecture based on two phase-coupled Ka-band microwave channels. These two channels will be for the transmitted signal and coherent local oscillator (LO) for IQ downconversion, respectively. As the two phase-coupled channels can be independently tuned or swept with a controlled frequency offset, the same microwave chain can also support profile-reflectometry measurements using cutoff-delay information.
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All authors E. Wikarta, U. Kumar, V.H. Hall-Chen, D. Endrizzi, S.J. Frank, C.M. Jacobson, X. Li, D.A. Sutherland
Fluid Dynamics
Prediction of Viscoelastic Droplet Impact Dynamics Using a Vision Transformer-Based Approach
Diego A. de Aguiar and Cassio M. Oishi
Droplet impact on solid surfaces is a complex fluid dynamics problem with applications in spray cooling, inkjet printing, and pharmaceutical processing. Although numerical simulations are widely used to investigate these dynamics, their computational cost becomes significant when multiple parametric variations are considered. In this work, we investigate the use of a
Video Vision Transformer (ViViT) architecture to predict the temporal
evolution of viscoelastic droplets impacting solid surfaces using volume fraction fields obtained from the Volume of Fluid (VOF) method. In Newtonian fluids, impact dynamics are mainly characterized by the Reynolds number $Re$, representing the ratio of inertial to viscous forces, and the Weber number $We$, representing the ratio of inertial to surface tension forces. For viscoelastic fluids, additional parameters are required to account for elastic effects, namely the solvent viscosity ratio $\beta$ and the Weissenberg number $Wi$, increasing simulation complexity and cost. Instead of simulating the entire droplet dynamics, the proposed approach uses only the initial 10% to 20% of the simulation to predict the remaining
evolution. Depending on the prediction configuration, this strategy reduces computational cost by approximately 80% to 90% compared to full numerical simulations. The ViViT produces physically consistent predictions across different parameters and prediction horizons, successfully capturing both spreading and bouncing regimes while preserving
geometric features and structural similarity. Since volume fraction fields can also be extracted from experimental
videos, the proposed framework could be extended to incorporate experimental data during training, potentially improving the physical fidelity of the predicted dynamics.
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Computational Physics · Cross-listed from quant-ph
Augmenting Imaginary-Time Evolution with Local Geometric Information
Carlos L. Benavides-Riveros, Prachi Sharma, Pietropaolo Frisoni et al. (+1 more)
Imaginary-time
evolution (ITE) underpins a broad family of
algorithms for ground-state preparation in
quantum simulation and
quantum many-body physics. In these methods, convergence is governed by the energy variance of the instantaneous state, causing the flow to approach the ground state only asymptotically. We introduce an augmented imaginary-time
evolution (AITE) framework that replaces the standard gradient flow on the energy landscape with a geometrically informed descent along locally optimal directions, which are identified by exploiting the higher-order statistical structure of the instantaneous energy distribution. The resulting flow strictly outperforms standard ITE throughout the entire
evolution and exhibits two qualitatively distinct regimes: a superlinear convergence regime, followed by an extinction regime in which the energy error vanishes exactly at a finite value of the imaginary-time flow parameter, in contrast to the asymptotic exponential decay of ITE. Standard ITE is recovered in the zero-skewness limit of AITE, implying that the acceleration extends naturally across the broader ITE algorithmic family.
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All authors Carlos L. Benavides-Riveros, Prachi Sharma, Pietropaolo Frisoni, Fedor Šimkovic IV
Optics
Scalable reflective communication for microscopic electronics
Matthew F. Campbell, Kyle Skelil, Chaitanya Karimanasseri et al. (+6 more)
Untethered microscopic electronic
circuits hold the potential for extraordinary advances in many fields such as neural transmitting and distributed sensing. However, establishing uplink communications from the microscale back to the macroscopic world remains challenging; existing micro-transmitters are difficult to integrate with
semiconductor processing. Here we surmount this obstacle, introducing a strategy for modulating backscattered
photons based on the electrochromic
polymer PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) that is scalable to micron-order sizes and manufacturable using standard parallelizable methods. Our devices, which we call SPOTs (submillimeter
polymer optical transmitters), actuate at low voltages (< +/-1 V), switch in as fast as 10 {\mu}s, can run for millions of cycles, and operate seamlessly in electrolytes. We achieve this design by emphasizing architectural simplicity and mass-manufacturability rather than traditional metrics such as data rates or energy costs. As a demonstration, we develop SPOT-equipped temperature-sensitive photovoltaic-powered foundry-fabricated microchips and use them to wirelessly measure and transmit local temperatures. These results represent an important step toward fully-integrable, micron-scale bidirectional communication.
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All authors Matthew F. Campbell, Kyle Skelil, Chaitanya Karimanasseri, David Gonzalez-Medrano, Li Xu, Jungho Lee, David T. Blaauw, Igor Bargatin, and Marc Z. Miskin
Atomic Physics
Analysis of the frequency shift in coherent population trapping resonance's dynamic continuous-wave spectroscopy at the phase-jump modulation and its comparison with the conventional approach
E. D. Chivilis and E. A. Tsygankov
We present the research of dynamic continuous-wave spectroscopy of the coherent population trapping resonance at the phase-jump modulation. {\Lambda} system of levels supplemented by a nonabsorbing state and bichromatic optical field, whose spectral components have different intensities, are considered. We demonstrate that the asymmetry leads to an additional nonlinear shift of the error-signal frequency under unisotropic relaxation of the ground-state density-
matrix elements. We also investigate the conventional approach where the frequency difference of the optical field components is harmonically modulated to obtain the error signal. Comparison demonstrates that in the high-frequency modulation regime the corresponding frequency shift is more linear than at the phase-jump modulation for nonshort integration times.
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Fluid Dynamics
On initiation of detonation in large fuel-air clouds
Leonid Kagan, Peter V. Gordon and Gregory Sivashinsky
The proposed study is motivated by experimental evidence, dating back to 1985, demonstrating the possibility of deflagration-to-detonation transition (DDT) in a fuel-air cloud. The detonation is initiated by a flame jet developed in a thin open-ended tube inserted into the cloud. Despite the experimental data, a first-principle understanding of the mechanism controlling the transition is still missing. The current research is aimed at resolution of this issue through a simple 2D formulation involving minimum physical ingredients.
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Chemical Physics
Charge transfer from ammonia neutralizes propylene oxide cations: Implications for the astrochemistry of chiral molecules
Sanjana Maheshwari, Darya Kisuryna and Leah G. Dodson
To date only one
chiral species, propylene
oxide, has been observed in the interstellar medium but little is known about the chemistry that leads to a detectable abundance of this molecule in Sagittarius B2. We used a glow-discharge ion source and a room-temperature ion trap to study the neutralization reactions necessary to convert propylene
oxide cation (PO$^+$) – the assumed precursor for propylene
oxide in space – into the observed astrochemical. We found that the charge-transfer reaction between PO$^+$ and ammonia (NH$_3$) proceeds with a pressure-independent rate coefficient of $(1.39\pm0.03)\times10^{-12}$ cm$^{3}$ s$^{-1}$ to neutralize PO$^+$ and form the radical cation NH$_3$. Although this measured rate coefficient is much slower than that predicted by capture theories, the high abundance of NH$_3$ in Sagittarius B2 motivates the inclusion of this reaction in astrochemical models. We hypothesize that the low ionization energies of many
chiral molecules important to origin-of-life theories means these species may exist as cations in the interstellar medium.
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Data Analysis and Statistics · Cross-listed from astro-ph.IM
Astrobiology in the Time of Artificial Intelligence
Caleb Scharf
The Viking missions showcased multiple spaceflight technologies representing state-of-the-art capabilities: from digital line-scan imaging to the operation of complex onboard laboratories and software-controlled process autonomy. Since Viking, there have been extraordinary, and still accelerating, advancements in computing technology impacting science, society, and exploration. These developments have occurred in both hardware and software, resulting in increasingly capable devices, advanced programming tools, and algorithmic innovations. The subset of artificial intelligence known as machine learning has emerged as one of the most transformative of these developments, with major implications for space exploration and for improvements to the search for evidence of life beyond the Earth. Those improvements include the integration of data across different scales and increased sensitivity to complex features in data, as well as the generation of adaptive strategies for sampling environments. In this paper, the present and future nature of space exploration and astrobiological research is examined through the contextual lens of Viking, and through the history and possible future of artificial intelligence.
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Atomic Physics
Non-adiabatic Effects Induced by Strong Light-Matter Coupling in Cavity QED
T. Zalialiutdinov, D. Solovyev, J. J. Lopez-Rodriguez et al. (+2 more)
We present a systematic study of the diagonal Born-Oppenheimer correction (DBOC) for atoms and molecules embedded in optical cavities and interacting with a quantized electromagnetic field. By explicitly evaluating the
nuclear kinetic energy operator, we analyze cavity-induced modifications of DBOC within a
quantum electrodynamics configuration-interaction (QED-CI) framework built on
quantum electrodynamics Hartree-Fock (QED-HF) and strong-coupling
quantum electrodynamics Hartree-Fock (SC-QED-HF) reference states. The analysis covers a diverse set of atomic and molecular systems, including He, H-, Be, H2, LiH, HF, ammonia (NH3), and formaldehyde (CH2O). We show that the presence of the cavity leads to shifts in molecular dissociation energies on the order of a few inverse centimeters. For several atomic systems, the inclusion of the DBOC yields a pronounced effect, with the correction magnitude reaching the experimental resolution. These findings reveal finite
nuclear mass effects as an essential component of
nuclear dynamics in cavity QED and suggest their relevance for precision analysis in strongly coupled light-matter systems.
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All authors T. Zalialiutdinov, D. Solovyev, J. J. Lopez-Rodriguez, A. Anikin, A. Kotov
Computational Physics · Cross-listed from cs.LG
The Degeneracy Distillery
T. Lucas Makinen, Deaglan J. Bartlett, Niall Jeffrey et al. (+1 more)
When two or more parameters or labels produce similar data, they are degenerate, or hard to distinguish. Degeneracies render both label prediction and inverse problems difficult, since both machine learning
algorithms and probabilistic samplers rely on the distinguishability of data and its gradients with respect to parameters. However, identifying degeneracies in physical models or real-world
datasets can be elucidating about the choice of model or the underlying process that produces the data. We present the degeneracy distillery, a method that (1) detects and (2) resolves degenerate parameter combinations (a) automatically and (b) symbolically, from parameter-data (or parameter-simulation) pairs alone, through estimation and flattening of the Fisher information
matrix. By exploring the information geometry of the likelihood, we characterize degeneracies as an intrinsic property of the physical model, requiring no realised data observation. We demonstrate our approach on a range of synthetic and real-world problems, discovering symbolic coordinate transformations that identify the combinations of parameters of a model which yield independent effects on the data. The resulting coordinates flatten the Fisher information in expectation globally, in contrast to posterior-based methods that flatten only at a single point, and substantially reduce the simulation budget required for downstream neural posterior estimation. In test cases we require up to $10\times$ fewer simulations for posterior estimation at matched validation calibration whilst simultaneously gaining physical insight on the system.
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All authors T. Lucas Makinen, Deaglan J. Bartlett, Niall Jeffrey, Benjamin D. Wandelt
Optics · Cross-listed from quant-ph
Mode-selective nonlinear interference for high-brightness and high-purity fiber-coupled SPDC sources
Carlos Sevilla-Gutiérrez, Purujit Singh Chauhan, Varun Raj Kaipalath et al. (+1 more)
Single-mode-fiber-coupled spontaneous parametric down-conversion (SPDC) sources are a key resource for photonic
quantum technologies, but in single-
crystal geometries brightness, heralding efficiency, and spectral purity remain constrained by intrinsic trade-offs. Here, we show how nonlinear interference in a cascaded two-
crystal type-II SPDC source can be used to engineer the modal structure of SPDC emission, improving the brightness–heralding-efficiency trade-off by more than one order of magnitude beyond the single-
crystal limit. We further demonstrate two routes to near-unity spectral purity while retaining high brightness and/or heralding efficiency, even with standard periodically poled
crystals, and study the additional advantages of aperiodic poling with Gaussian phase matching. Using a spectrally resolved Laguerre–Gauss modal decomposition, we show that these improvements arise from mode-selective interference of spatial-spectral SPDC modes within the nonlinear interferometer. We experimentally validate the model through sum-frequency-generation measurements of the spatial-spectral state.
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All authors Carlos Sevilla-Gutiérrez, Purujit Singh Chauhan, Varun Raj Kaipalath, Fabian Steinlechner
Atmospheric and Oceanic Physics
From stable online coupling to decade-long climate simulations: A machine learning parameterization for cloud microphysics in ICON
Ellen Sarauer, Mierk Schwabe, Philipp Weiss et al. (+3 more)
The representation of cloud microphysics and its nonlinear character and scale-dependence is a remaining source of uncertainty in Earth system models (ESMs). Here, we develop and couple online a machine learning (ML)-based cloud microphysics parameterization with the Icosahedral non-hydrostatic modeling framework (ICON). The primary challenge is achieving numerically stable, long-term online coupling when transitioning from training with km-scale data to application in coarse-scale simulations, where the coupled system encounters atmospheric states and feedbacks not seen during training. The training data is obtained from a global convection-permitting ICON simulation at 5 km resolution. The ML microphysics scheme uses a two-stage design: a classifier to identify active grid
cells and a regressor to predict cloud microphysical tendencies. Physical constraints such as enforcing mass positivity and overshoot prevention prove essential for numerical stability in the coupled system. We demonstrate that achieving stable online coupling requires enforcing physical constraints and careful
dataset curation, and that strong offline performance alone is insufficient. The coupled model maintains numerical stability over decade-long simulations with a performance in reproducing the observed
climate comparable to the classical graupel scheme. The ML-based scheme eliminates two microphysics-specific tuning parameters of the classical graupel scheme, though systematic improvements in long-term mean-state biases are not yet realized. This study demonstrates that stable, decade-long
climate simulations with an ML-based cloud microphysics scheme trained on convection-permitting data are feasible, providing a foundation for future hybrid ESMs.
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All authors Ellen Sarauer, Mierk Schwabe, Philipp Weiss, Axel Lauer, Philip Stier, Veronika Eyring
Physics and Society · Cross-listed from eess.SY
Rethinking the green power grid for stability, not just for climate
Yiming Wang, Arthur N. Montanari and Adilson E. Motter
The 2025 Iberian blackout has renewed concerns about the resilience of power grids with high shares of renewable generation. This commentary argues that renewable generation can not only advance decarbonization but also strengthen grid stability through synthetic inertia, advanced inverter-based control, and coordinated transmission planning. Rapid advances in energy storage and power electronics make this transition increasingly viable.
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Data Analysis and Statistics · Cross-listed from quant-ph
Sebastian Murk, Ian Tan, Fabian Müller et al. (+1 more)
Quantum tomography and
quantum retrodiction are traditionally viewed as separate inference tasks. We show that the two are manifestations of the same underlying principle. We prove that the Petz recovery map of a measurement channel is a gradient of the log-likelihood used in maximum-likelihood
tomography, and we derive its extension to arbitrary
quantum channels. Consequently, for measurement channels, repeated applications of the Petz map monotonically increase the likelihood, naturally yielding a method for
quantum tomography.
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All authors Sebastian Murk, Ian Tan, Fabian Müller, Dominik Šafránek
General Physics
Unified Entropic Dynamics Framework for Classical, and Quantum Wave Equations
Shahid Nawaz, Muhammad Saleem, Muhammad S. Anwar et al. (+1 more)
Entropic Dynamics (ED) provides a statistical-inferential foundation for physical laws, deriving motion and field equations from principles of
entropy maximization rather than quantization postulates. ED reconstructs
quantum mechanics by treating the
evolution of probability distributions on configuration space as driven by information constraints, yielding the Schrodinger equation as a non-dissipative
diffusion process. Building on this foundation, the present work extends the ED framework into a Unified Entropic Dynamics (UED) formulation that encompasses classical,
quantum, relativistic, thermodynamic, and gravitational phenomena within a single information
geometric principle. By maximizing
entropy subject to constraints on
diffusion, drift, and gauge covariance over a
manifold endowed with a supermetric H_ab, we derive a universal field equation that merges the Fokker-Planck and Hamilton-Jacobi structures into one covariant form. When specialized to different dynamical variables, this equation reproduces the harmonic oscillator, Schrodinger, Maxwell, Klein-Gordon, and gravitational wave equations, thereby revealing a deep equivalence between probabilistic inference and dynamical law. The UED framework demonstrates that spacetime geometry,
quantum coherence and thermodynamic
diffusion emerge as complementary expressions of the same entropic process, establishing a unified inferential foundation for both microscopic and macroscopic physics. In this formulation, energy, probability, and
entropy are intertwined aspects of information geometry, providing a consistent inferential foundation for understanding classical,
quantum, and gravitational dynamics as complementary expressions of a single entropic law.
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All authors Shahid Nawaz, Muhammad Saleem, Muhammad S. Anwar, Dalaver H. Anjum
Biological Physics · Cross-listed from cond-mat.stat-mech
Effective hyperuniformity in time-integrated stochastic Turing patterns
Anirban Mukherjee and Hong-Yan Shih
Demographic noise generates
stochastic Turing patterns even when reaction-
diffusion systems are deterministically stable. We show analytically and verify numerically in the Levin-Segel model that temporal integration of configurations reveals emergent large-scale organization. The intensive number variance in a window of size $R \gg 1$ approaches a finite reaction-kinetic floor as $1/R$, over a spatial range growing by orders of magnitude near the Turing instability. This yields an effectively hyperuniform, fine-tuning-free regime previously unidentified in non-conserved multispecies
stochastic systems.
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Atmospheric and Oceanic Physics
The Dataset Friction Framework: measuring user-facing friction as a complement to FAIR
Emma Pidduck and Umberto Modigliani
Open research data services have matured to the point where the cost of sustaining them at scale has become a primary design constraint, driving providers to make deliberate choices that may reduce user convenience to keep the service viable. The FAIR (Findable, Accessible, Interoperable, Reuseable) principles describe whether a
dataset is well stewarded, and FAIR compliance is often treated as a proxy for usability. FAIR does not capture the cost to a user of finding, accessing, interpreting, and applying a
dataset. We introduce the
Dataset Friction Framework (DFF) as a complement to FAIR, directly addressing usability. DFF measures user-facing friction across six dimensions, distinguishing engineered friction (deliberate data provider design choices that sustain a service) from accidental friction (defects that require remediation). The framework is validated against 18,556 support tickets from the European Centre for Medium-Range Weather Forecasts (January 2024 to May 2026), which serves 280,000 registered users. Restricting the analysis to tickets raised by external reporters reduces the corpus by 12.3%, but every dimension's internal-staff share falls below this baseline – confirming that the reported friction signals are genuinely user-facing. We then assess three real
datasets across three providers and show that FAIR compliance and DFF friction can disagree in both directions: a 92% FAIR-compliant
dataset can still carry substantial friction, and a 42% FAIR score can be an artefact of anti-scraping policy rather than poor stewardship. The two measures are non-redundant and jointly informative: FAIR compliance does not predict DFF friction in either direction. This constitutes the first large-scale empirical application of the framework; cross-institutional validation is identified as the immediate next step.
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