Instrumentation and Detectors
Physics at the Edge: Benchmarking Quantisation Techniques and the Edge TPU for Neutrino Interaction Recognition
Stefano Vergani, Hilary Utaegbulam, Michael Wang et al. (+3 more)
This work presents a
benchmark of quantisation techniques for convolutional neural networks applied to
neutrino interaction recognition, motivated by the need for low-power inference close to the detector in future
liquid argon time-projection chamber (LArTPC) experiments. Using simulation of a generic LArTPC, four Keras models are trained to classify neutral-current,
muon-
neutrino charged-current and electron-
neutrino charged-current interactions, quantised using post-training integer quantisation and quantisation-aware training, and deployed on the Google Coral Edge TPU. Latency and energy per event are compared with those of an Intel Core i7-13650HX CPU, a consumer NVIDIA RTX 4060 GPU and a data-centre NVIDIA A100 GPU, using measured energy at different batch sizes and thread counts; the energy of the Edge TPU is estimated from its nominal power. The accuracy degradation is strongly model-dependent: InceptionV3 shows no significant loss along either pipeline, whereas the other models are substantially degraded. At batch size 1, the Edge TPU is comparable to or faster than the CPU and 1.3-6.5 times slower than the A100, while requiring 5–70 times less energy per event than the other devices; with batching, the GPUs reduce this gap to a factor of 2.6-7.2. The Edge TPU is also approximately four times cheaper than the consumer GPU and more than two orders of magnitude cheaper than the A100. Its low power per device eases deployment where power and cooling are constrained, with an additional benefit in terms of environmental impact. This paper explores possible future integrations of edge AI technologies with
neutrino physics.
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All authors Stefano Vergani, Hilary Utaegbulam, Michael Wang, Leigh H. Whitehead, Arden S. H. Tsang, Lorenzo Uboldi
Instrumentation and Detectors
Offline Commissioning of the St. Benedict Gas Catcher
F. Rivero, D. Guillet, M. Brodeur et al. (+11 more)
Precision measurements of $\beta$ decay transitions offer a promising channel through which the Standard Model (SM) can be probed. There is currently an ongoing effort to increase the precision on measurements of $\mathcal{F}t$-values for superallowed $\beta$ decay transitions between mirror nuclides. These allow for a determination of $V_{ud}$ which is complementary to that obtained from pure
Fermi $0^+ \rightarrow 0^+$ transitions. The Superallowed Transition BEta-
NEutrino Decay Ion Coincidence Trap (St. Benedict), under construction at the
Nuclear Science Laboratory (NSL) at the University of Notre Dame, seeks to measure the
Fermi-to-Gamow-Teller mixing ratio for transitions between mirror
nuclei in order to expand the list of nuclides from which $V_{ud}$ can be extracted. Production and selection of the species of interest will be done in-flight, using the TwinSol
magnetic separator system. The first element of St. Benedict will be a large volume gas catcher which will thermalize radioactive ion beams for low energy delivery to the rest of the system. Offline commissioning of this gas catcher has been completed using an internal potassium source, and the device demonstrated a transport efficiency upwards of 95% for pressures of 66 mbar and lower.
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All authors F. Rivero, D. Guillet, M. Brodeur, J.A. Clark, A.M. Houff, J.J. Kolata, B. Liu, J. McRae, P.D. O'Malley, W.S. Porter, C. Quick, G. Savard, A.A. Valverde, R. Zite
History and Philosophy of Physics
Ceci n'est pas un gluon
India Bhalla-Ladd, Eleanor March and James Owen Weatherall
We discuss and then resolve a tension between how physicists treat gauge
bosons and the celebrated "Wu-Yang dictionary", which identifies particle physics terminology with that of principal bundles and principal connections. We show how this tension leads to an interpretative choice that is not widely discussed in the physics literature. We then show how the same considerations present a dilemma for a recent "particle-first" approach to Yang-Mills theory due to Henrique Gomes. Either the particle-first approach has surplus structure as compared to principal-bundle-based approaches, or gauge
bosons are not sections of vector bundles.
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Accelerator Physics
AI-Ready Control System for the Fermilab Accelerator Complex
Tia Miceli, Erik Gottschalk, Donovan Tooke et al. (+15 more)
Reliable, high-intensity operation of the Fermilab Accelerator Complex is critical to the success of the Long-Baseline
Neutrino Facility and Deep Underground
Neutrino Experiment. We describe the requirements and infrastructure necessary to support routine use of artificial intelligence and machine learning (AI/ML) in the accelerator control system. Three capabilities are identified: a machine learning operations (MLOps) framework standardizing the lifecycle of AI/ML automation from data management through deployment and monitoring; a data quality framework defining and enforcing standards required to build trustworthy AI/ML applications; and workflow integration with large
language models to assist physicists, engineers, and operators with information
retrieval, code development, and routine analysis. Use cases spanning beam diagnostics, beam control, and support system automation illustrate the technical requirements across the complex.
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All authors Tia Miceli, Erik Gottschalk, Donovan Tooke, Evan Milton, Robert Santucci, Hayden Hoschouer, Michael Balcewicz, Jennifer Case, Abhishek Deshpande, Kit Fieldhouse, Sudeshna Ganguly, Beau Harrison, Aisha Ibrahim, Thomas Kobilarcik, Michael Olander, Abhishek Pathak, Jason St. John, Aaron Sauers
Chemical Physics
A Lanczos-based algorithm for sum-over-states calculations of NMR spin–spin coupling constants at the RPA level of theory: The Fermi-contact term
Sarah L. V. Zahn, Luna Zamok, Sonia Coriani et al. (+1 more)
The analysis of
nuclear magnetic resonance parameters, such as the indirect
nuclear spin-
spin coupling constants, in terms of contributions from localised molecular orbitals is a commonly used approach for gaining a deeper understanding of experimentally observed trends in these parameters. In the vast majority of these studies, contributions from pairs of one occupied and one virtual orbital are calculated and analyzed. Analyses in terms of two pairs of an occupied and a virtual orbital, that would allow for the study of coupling pathways, are much more seldom, as they require calculating the coupling constants as a sum over all excited states. Previous studies have shown that, for the often dominating
Fermi-contact contribution to the coupling constants, more or less all excited states have to be calculated when employing a Davidson
algorithm, because the most high-lying excited states can also make a significant contribution to the
Fermi-contact term. In this study we investigated therefore, whether by employing a Lanczos
algorithm one can obtain converged values of the
Fermi-contact contribution to the indirect
nuclear spin-
spin coupling constants already with a significantly smaller percentage of the total number of excited states included in the sum-over-states expression. To this purpose we have extended the recent implementation of a Lanczos
algorithm for the RPA/TDHF or TDDFT
eigenvalue problem in the Dalton program (L. Zamok et al. J. Chem. Phys. 156, 014102 (2022)). The new procedure was tested on 17 molecules containing first, second and third row atoms. We find that, for most coupling constants, less than 50% of the excited pseudo states are necessary for converging the
Fermi-contact term with an error of less than 0.5 Hz. For the few exceptions, typically for molecules with third-row atoms, around 60% were necessary.
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All authors Sarah L. V. Zahn, Luna Zamok, Sonia Coriani, Stephan P. A. Sauer
Atmospheric and Oceanic Physics
Machine Learning-Based Prediction of Heat Index in Selected U.S. Cities
Yushan Han and Calen Randall
Heat stress has harmful effects that impact communities across the Unitedt States, particularly when high temperatures are accompanied by high humidity. The combined impact of temperature and humidity can be summarized by the heat index (HI). Current state-of-the-art numerical weather prediction models are often biased when
forecasting temperature and humidity even within a 24-hour forecast lead time. This study explores the ability of machine learning (ML) models to accurately predict the next-day heat index using Random Forest and single-layer Gated Recurrent Unit (GRU) models in four locations across the United States. We find that Random Forest and GRU models perform reasonably well at all four selected locations. Mean absolute HI error ranges from 4.5 to 6.6 {\deg}F. All model versions have an accuracy rate exceeding 80% in three of the four locations in terms of successfully
forecasting an extreme heat day, as indicated by a high afternoon HI. The GRU model achieves over 95% accuracy in these three locations. Model performance details vary by location. In Minneapolis and Portland, which have relatively few days with high HI values, models' accuracy is high, but the recall and precision are generally very low. In contrast, Dallas, a location with many high HI days, shows moderately high accuracy, as well as extremely high recall and precision. These differences are likely due to distinct causes of heatwaves in different climatological regions of the United States, as reflected in the feature importance scores output by Random Forest models. The ML models designed in this study can be used to assist with local heat index
forecasting and extreme heat warning issuance at minimal computational cost.
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Computational Physics · Cross-listed from cond-mat.mes-hall
Energy renormalizations of resident carriers and excitons in transition metal dichalcogenide monolayers
Dinh Van Tuan, Junghwan Kim and Hanan Dery
Energy renormalizations of resident carriers and
excitons are studied theoretically, and compared with recent experiments of electrostatically-doped WSe$_2$ monolayers. The calculated energy renormalization of resident carriers, subjected to strong out-of-plane
magnetic field, reveals the importance of dynamical screening in transition metal dichalcogenides. The energy renormalization of tightly bound
excitons is analyzed through the exchange interaction between the electron (or hole) component of the
exciton and resident carriers that share the same
spin and valley
quantum numbers. Our theory explains the weak energy shift of excitonic resonances despite the strong energy renormalization of resident carriers. We identify the dependence of the energy renormalization on the envelope function of a tightly-bound
exciton, showing that unlike free electron-hole pairs, this energy renormalization is not the added renormalizations of a resident electron and resident hole.
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Computational Physics · Cross-listed from gr-qc
Observational imprints and quasi-Periodic oscillations of magnetically charged anti-de Sitter black holes
Faizuddin Ahmed, Mohsen Fathi and Ahmad Al-Badawi
In this work, we investigate observable signatures of a magnetically charged Anti-de Sitter black hole in string-inspired Euler-Heisenberg theory. We analyze
photon trajectories, the
photon sphere, and the resulting black hole shadow. We derive the
photon sphere and shadow radii and show that both deviate from the Schwarzschild and Schwarzschild-AdS cases. In particular, the radii decrease monotonically as the
magnetic charge parameter $Q_m$ increases, indicating that
magnetic charge modifies light propagation near the black hole. We also study neutral and charged particle motion and compute the corresponding epicyclic frequencies. Using the effective potential method, we obtain the specific energy and angular momentum for stable circular orbits and determine the innermost stable circular orbit (ISCO). The presence of $Q_m$ shifts the ISCO radius and alters the orbital structure. The radial, vertical, and orbital frequencies show clear deviations from the Schwarzschild case. Finally, we confront the model with twin-peak quasi-periodic oscillation (QPO) data from
stellar-mass, intermediate-mass, and supermassive black hole candidates. A two-dimensional Delta chi-square analysis in the ($r$, $Q_m$) space shows that the best fit corresponds to $Q_m=0$, although finite values remain allowed within confidence levels. At the 1 sigma level, we obtain an upper bound $Q_m/M$ less than about 0.2. These results indicate that while
magnetic charge produces measurable theoretical deviations, current QPO data place only moderate constraints on its magnitude.
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Fluid Dynamics
Coherent Structure Transport in Turbulent Axisymmetric Pipe Expansions
Jibu Tom Jose, Gal Friedmann and Omri Ram
Turbulent separated flows in axisymmetric expansions can sustain fundamentally different transport organization despite nearly identical mean
topology. Using stereo-PIV and time-resolved planar PIV, we compare abrupt $90^\circ$ (step) and gradual $45^\circ$ (wedge) axisymmetric expansions at step height Reynolds numbers of 25000 and 35000. Despite similar reattachment lengths, near-separation
turbulence differs, with the wedge exhibiting higher turbulent kinetic energy over a broader shear layer, while the step confines production to a thinner region near the corner, where a secondary
vortex weakens momentum and fluctuations. The spatial spectra reveal a pronounced spectral hump in the out-of-plane velocity fluctuations near separation. This feature is consistently observed across all cases and reflects the expansion effects on the redistribution of fluctuation energy associated with the interaction between the separating shear layer and the recirculating flow. Temporal spectra show no geometry-specific dominant frequencies, and space-time correlations indicate similar normalized convection velocities across all cases. The primary effect of geometry, therefore, does not lie in the characteristic scales or transport speeds, but in the spatial organization and persistence of coherence. The step cases exhibit stronger spectral concentration, longer local integral time scales, and a broader distribution of space-time correlations in convection velocities associated with momentum-depleted return flow. Finite-time Lyapunov exponent (FTLE) fields confirm that these differences extend to material transport, as the wedge produces larger and less fragmented deformation regions, while the step yields a more segmented pattern that persists downstream of reattachment.
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Chemical Physics
In situ Learning-Based Spin Engineering of Pulsed Dynamic Nuclear Polarization
Filip V. Jensen, José P. Carvalho, Nino Wili et al. (+6 more)
Pulsed Dynamic
Nuclear Polarization (DNP) is currently receiving substantial interest as a means to enhance the sensitivity of
nuclear magnetic resonance (NMR) and
magnetic resonance imaging (MRI) by orders of magnitude. It has also received much
attention as a central ingredient in many modalities of electron
spin-involved
quantum sensing. Relative to
spin engineering associated with NMR, the design of efficient pulsed DNP experiments with a broad experimental scope are challenged by large electron-
nuclear spin systems, large electron
spin-involved interactions, and instrumental non-idealities and limitations. All of this may challenge traditional NMR-like theoretical and numerical pulse sequence engineering. Exploiting state-of-the-art instrumentation and taking advantage of the high sensitivity of DNP relative to NMR, we here demonstrate the use of combinations of
Bayesian machine learning methods and constrained random walk procedures to design pulse sequences in situ, by experiments, directly on the
spin systems responding to spectrometer instructions. For trityl and nitroxide samples, it is demonstrated that efficient broadband DNP pulse sequences can be designed in situ with experimental protocols benchmarked against in silico analogs.
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All authors Filip V. Jensen, José P. Carvalho, Nino Wili, Asbjorn Holk Thomsen, David L. Goodwin, Lukas Trottner, Claudia Strauch, Anders Bodholt Nielsen, Niels Chr. Nielsen
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Auxetic Response in Two-Dimensional MXenes with Atomically Defined Perforations
Hossein Darban
Recent advances in nanoscale fabrication enable atomic-scale manipulation of two-dimensional (2D) materials by introducing engineered pores and perforations. This provides new opportunities to tailor functional properties of 2D materials for applications such as selective ion transport, desalination membranes, and molecular filtration. Despite this progress, the auxetic mechanical behavior of perforated 2D materials has received little
attention. In this work, large-scale reactive molecular dynamics (MD) simulations, validated against experimental measurements and first-principles calculations, are employed to investigate the mechanical response of perforated monolayer titanium-based MXene metamaterials. Architectures containing rectangular perforations with straight ligaments and sinusoidally curved ligaments are systematically examined under uniaxial tension and compression over a range of
geometric parameters and temperatures, from the onset of deformation to fracture. The results demonstrate that MXene metamaterials exhibit a tunable negative Poisson's ratio (NPR), which can be controlled through the perforation geometry and surface termination. Atomistic stress analysis reveals alternating in-plane shear stresses at the junctions that induce rotational deformation of the ligaments. This rotating-junction mechanism is coupled with out-of-plane deflections arising from the low bending
rigidity of atomically thin materials, producing complex three-dimensional deformations. Comparison with
graphene metamaterials indicates that the perforation geometry governs qualitative auxetic trends, whereas intrinsic material properties determine quantitative responses. These findings identify MXenes as a versatile candidate for the design of tunable 2D mechanical metamaterials and provide atomistic insight into the interplay between geometry, bending
rigidity, and auxetic deformation mechanisms.
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Optics
Large-amplitude diamond optomechanics by traversing a nonlinear attractor
Peyman Parsa, Waleed El-Sayed, Parisa Behjat et al. (+2 more)
Nonlinear dynamics clamp the amplitude of mechanical resonators driven into self-oscillation by optomechanical backaction. Here we overcome the conventional limits of self-oscillation amplitude by navigating the nonlinear dynamical landscape of a diamond optomechanical cavity supporting coherent optomechanics at room temperature. By exploiting the bistable phase space of the system, we increase the oscillation amplitude by nearly an order of magnitude. This enhancement arises from deterministic access to a high-energy state in the system's nonlinear attractor, and is accompanied by the generation of an optical frequency comb produced by cascaded
phonon scattering that underlies the nonlinear dynamics. Our results establish nonlinear attractor engineering as a route to large amplitude coherent
phonon generation and provide a platform for optomechanical frequency combs,
spin mechanical interfaces in diamond, and precision sensing in ambient conditions.
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All authors Peyman Parsa, Waleed El-Sayed, Parisa Behjat, Shabir Barzanjeh, Paul E. Barclay
Applied Physics
Single-Crystal AlN Wafer-Based Bulk Acoustic Resonators for Piezoelectric Power Conversion
Ziqian Yao, Clarissa Daniel, Kaicheng Pan et al. (+5 more)
In this work, we demonstrate the first single-
crystal aluminum nitride (AlN) wafer-based thickness-extensional (TE) mode bulk acoustic resonator for piezoelectric power conversion. The device exhibits a high series resonance 3-dB quality factor ($Q$) of 1677 and an electromechanical coupling coefficient ($k^2$) of 6.1%, highlighting the strong potential of AlN resonators for efficient power conversion. To suppress in-band spurious modes, a grounded ring structure is proposed and experimentally validated. The measured frequency-domain impedance response shows a spurious suppression of the spectrum above the resonance at 13.52 MHz. A comparative analysis with prior PZT, LN, and LT-based resonators indicates that AlN achieves a competitive figure of merit and $f \cdot Q$ product, while its material thermal conductivity is orders of magnitude higher than that of the incumbent piezoelectric power-converter resonators. The power-handling capability is expected to be superior in AlN single-
crystal wafers and will be demonstrated in ongoing experiments. These results suggest that AlN offers a promising platform for compact, robust piezoelectric power converters and next-generation power electronic systems.
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All authors Ziqian Yao, Clarissa Daniel, Kaicheng Pan, Tzu-Hsuan Hsu, Heather Chang, Mark S Goorsky, Juan Rivas-Davila, Ruochen Lu
Medical Physics
Beyond the Tumor: Recurrence-Prone Radiomics for Prognostication in Negative PSMA PET/CT scans of Prostate Cancer
Fereshteh Yousefirizi, Sara Harsini, Mobin Mohebi et al. (+14 more)
In patients with biochemical recurrence of prostate cancer and negative PSMA PET/CT, radiomics features extracted from recurrence-prone organs can predict clinical progression and progression-free survival. In a cohort of 132 patients, combining PET/CT radiomics with clinical variables significantly improved prognostic performance (C-index 0.74 vs. 0.65). Model performance was influenced by reader diagnostic certainty and remained robust on external validation. These findings suggest that radiomics from visually negative scans capture subclinical disease and provide added value for risk stratification.
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All authors Fereshteh Yousefirizi, Sara Harsini, Mobin Mohebi, Ian Alberts, Tahir Yusufaly, Monica Luo, Hamid Abdollahi, Elmira Yazdani, Soheila Mirabedin, Maziar Sabouri, Parham Geramifar, Peyman Sheikhzadeh, Patrick Martineau, Don Wilson, Francois Benard, Carlos Uribe, Arman Rahmim
Applied Physics · Cross-listed from cond-mat.soft
Deciphering Molecular Charge Anisotropy: the Case of Antibody Solutions
Fabrizio Camerin, Susana Marin-Aguilar, Anna Stradner et al. (+2 more)
Electrostatic interactions fundamentally govern the structure, stability, and dynamics of charged (bio)matter, yet the impact of heterogeneous and anisotropic charge distributions on the behavior of
protein solutions remains elusive. Here, we introduce a versatile multiscale framework that directly connects molecular-level electrostatics to collective properties via a colloid-inspired coarse-grained modeling combined with neural network-assisted optimization. Using monoclonal antibodies as model system, our inverse design approach identifies charge patterns capable of reliably reproducing experimental structure factors, osmotic compressibility and collective
diffusion coefficients in a wide region of
protein concentrations. Close inspection of our data further uncovers how specific physical features and spatial arrangements of localized charge patches significantly influence the solution structure. This transferable strategy provides a predictive pathway to decode and control charge-driven interactions in complex biomolecules and, more generally, in heterogeneously-charged soft matter systems, with immediate relevance to
protein formulation and biomaterials engineering.
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All authors Fabrizio Camerin, Susana Marin-Aguilar, Anna Stradner, Peter Schurtenberger, Emanuela Zaccarelli
Space Physics
New Constraints on the Jovian Narrowband Radio Components from Juno/Waves Observations and 3D Geometrical Simulations
Boudouma Adam, Zarka Philippe, Louis Corentin et al. (+2 more)
Measurements of Waves instrument onboard the Juno spacecraft suggest that narrowband kilometric radiation (nKOM; 20-141 kHz) and narrowband low-frequency radiation (nLF; 5-70 kHz) are generated within the
plasma near the Io
plasma torus (IPT) in low-latitude regions. While these emissions are thought to result from the conversion of the natural modes of the
plasma into escaping
radio waves, at either the fundamental or the first harmonic of the
plasma frequency, there is no consensus on the specific mechanism involved. Using the electron density and the
magnetic field data from the Jovian Auroral Distribution Experiment (JADE) and the FluxGate Magnetometer (FGM), we determine the range of frequencies accessible to different wave modes during Juno's crossing of the
plasma disk environment. We classify the observed nKOM and nLF according to their propagation modes: trapped (Z-mode or Whistler), escaping (X-mode or O-mode), and undetermined (either trapped or escaping). We apply the 3D numerical modeling method that was developed in Boudouma et al. (2024) to the escaping and undetermined nKOM and nLF observations, deriving macroscopic constraints on the generation mechanisms, wave modes, characteristic frequencies, beaming and source locations. Our results support the interpretation in which high-latitude nKOM is consistent with O-mode, while low-latitude is rather X-mode. Both nKOM and nLF appear to be generated near the fundamental of the
plasma frequency, but only nLF shows compatibility with emission near the first harmonic, suggesting the possible coexistence of both linear and nonlinear generation mechanisms.
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All authors Boudouma Adam, Zarka Philippe, Louis Corentin, Imai Masafumi, Briand Carine
Fluid Dynamics
Investigation of Differential Diffusion and Strain Coupling in Large Eddy Simulations of Hydrogen-Air Flames
Antonio Masucci, Gioele Ferrante, Tiziano Ghisu et al. (+2 more)
Large Eddy Simulations with flamelet-based thermochemistry are used to investigate the behaviour of a premixed hydrogen-air flame stabilised by a bluff-body. Validation against experimental data is carried out first to demonstrate the model's ability to predict both velocity field and flame structure. The capability of the model in predicting differential
diffusion effects is then assessed, in particular regarding the coupling between differential
diffusion, tangential strain and
curvature, and their effect on mixture fraction redistribution and reaction rate variation. Results indicate that unstretched flamelet thermochemistry is capable of capturing the increase in mixture fraction caused by positive resolved strain, as well as negative variations of mixture fraction due to negative
curvature. Furthermore, the model is observed to mimic the effects of negative Markstein length to a certain extent, so that positive tangential strain causes reaction rate increase. The interplay between resolved stretch and preferential
diffusion is also shown to lead to a shorter flame length which is in better agreement with experimental observations as compared to simulations under unity Lewis number assumption. These findings highlight that the macroscopic effects of differential
diffusion and stretch on the premixed hydrogen flame, characterised by significant strain levels, can be predicted using a flamelet-based approach and without recurring to strained flamelets database, which implies important simplifications in the combustion modelling of turbulent hydrogen-premixed flames and offers valuable insights for the design of novel combustors.
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All authors Antonio Masucci, Gioele Ferrante, Tiziano Ghisu, Andrea Giusti, Ivan Langella
Fluid Dynamics
Power spectra via the van der Waals effect in the two-dimensional Poiseuille and Couette flow
Rafail V. Abramov
We numerically simulate the two-dimensional inertial flow with the van der Waals effect in a straight periodic channel around the Poiseuille and Couette stationary states. Even though the flow remains laminar macroscopically, we observe complex dynamics and power decay of the
Fourier spectra of small fluctuations of the density, velocity divergence, vorticity and kinetic energy of the flow near their respective stationary background states. Remarkably, pinning the vorticity to its background state, and leaving only the density and velocity divergence as the variables, results in the dynamics and power decay of the
Fourier spectra qualitatively similar to those of the full system. This strongly indicates that the underlying physics of the power spectra reside primarily in the density and velocity divergence variables, and are not directly related to the vorticity of the flow.
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Fluid Dynamics
Reduction of Triadic Interactions Suppresses Intermittency and Anomalous Dissipation in Turbulence
Anikat Kankaria, Ritwik Mukherjee, Sugan Durai Murugan et al. (+2 more)
We investigate how the defining statistical features of three-dimensional
turbulence respond to systematic reductions of the
Fourier-space triadic interaction network. Using direct numerical simulations of both fractally and homogeneously decimated Navier-Stokes dynamics, we show that progressive thinning of the set of active modes leads to a systematic suppression of intermittency and, most strikingly, to the vanishing of the mean dissipation rate in the large-Reynolds-number limit. Structure-function exponents collapse onto their dimensional values, the multifractal singularity spectrum contracts, and the analyticity width extracted from the exponential spectral tail increases monotonically with decimation-each indicating a substantial regularization of the velocity field. Together, these results provide direct evidence that anomalous dissipation in incompressible
turbulence is not a generic property of the Navier-Stokes equations, but instead requires the full combinatorial richness of their triadic nonlinear interactions.
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All authors Anikat Kankaria, Ritwik Mukherjee, Sugan Durai Murugan, Marco Edoardo Rosti, Samriddhi Sankar Ray
Applied Physics · Cross-listed from eess.SP
Channel Estimation via Tensor Decomposition for Dynamic Metasurface Antennas with Known Mutual Coupling: Algorithms and Experiments
Jean Tapie, Bruno Sokal, André L. F. de Almeida et al. (+1 more)
Dynamic metasurface
antennas (DMAs) are an emerging hybrid-
MIMO technology distinguished by an ultrathin form factor, low cost, and low power consumption. In real-world DMA prototypes, mutual coupling (MC) between meta-elements is generally non-negligible; some architectures even deliberately exploit strong MC to enhance wave-domain flexibility. In this paper, we address channel estimation (CE) for DMAs with known MC by formulating it as a tensor-decomposition problem. We develop a generalized block Tucker alternating least squares (BTALS)
algorithm, together with specialized variants for cases with known direct and/or feed channel. We also develop a reciprocity-aware bilinear factorization method for the case with known direct channel. We experimentally validate our
algorithms using an 18 GHz DMA prototype whose 7 feeds and 96 meta-elements are strongly coupled via a chaotic cavity. Our general BTALS
algorithm reaches an accuracy of 43.1 dB, only 0.3 dB below the upper bound imposed by experimental noise. All proposed
algorithms generally outperform the prior-art reference scheme thanks to the superior noise rejection enabled by the tensor-based framework. We further study the minimum number of required measurements as a function of the number of feeds and demonstrate the importance of MC awareness by comparison with an MC-unaware
benchmark. Finally, we apply BTALS to a second setup enabling the prediction of the DMA's full dual-polarization 3D radiation diagram. We also measure the latter for DMA configurations optimized for channel-gain enhancement based on the estimated channels. Altogether, our work establishes the practical relevance of MC-aware tensor methods; beyond DMAs, it applies to all wireless systems with wave-domain programmability enabled by tunable lumped elements.
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All authors Jean Tapie, Bruno Sokal, André L. F. de Almeida, Philipp del Hougne
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Photoferroelectric Coupling and Polarization-Controlled Interfacial Band Modulation in van der Waal Compound CuInP2S6
Subhashree Chatterjee, Rabindra Basnet, Rajeev Nepal et al. (+1 more)
Understanding how optical excitation couples with polarization and interfacial electrostatics in van der Waals (vdW) ferroelectrics (FEs) is essential for the development of light-programmable nanoelectronic and optoelectronic devices. Here, we present direct nanoscale evidence of photoferroionic coupling in the vdW FE
semiconductor CuInP2S6 (CIPS), where optical excitation jointly modulates electronic band bending, FE switching, and Cu+ ionic relaxation. The use of correlated Kelvin probe force microscopy, piezoresponse force microscopy, and conductive atomic force microscopy under above-bandgap illumination reveals illumination-induced enhancement of surface work function, persistent surface photovoltage, reduced coercive field, and positive imprint shifts. These effects arise from synergistic photocarrier redistribution and slow Cu+ migration that reshape interfacial depletion widths and internal electric fields. Illumination-assisted barrier lowering further enhances carrier injection and produces sweep-rate-dependent ferroionic transport hysteresis. Our results establish photoferroionic coupling as the governing mechanism for light-controlled band modulation and polarization stability in CIPS, providing a nanoscale framework for designing light-addressable FE
memories, optoelectronic switches, and neuromorphic devices based on layered ferroionic materials.
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All authors Subhashree Chatterjee, Rabindra Basnet, Rajeev Nepal, Ramesh C. Budhani
Instrumentation and Detectors · Cross-listed from astro-ph.IM
High efficiency superconducting filterbank with impedance-defined resolution for millimeter-wave spectroscopy
Oliver Jeong, Michel Piat and Aritoki Suzuki
We present a high efficiency, moderate resolution on-chip superconducting filterbank spectrometer designed for line intensity mapping and broadband wave-like dark matter searches. Existing implementations used by the millimeter-wave community rely on resistive feedline termination for standing wave mitigation which caps the per-channel efficiency $\eta_\mathrm{ch}$ at 50% and utilize microstrip resonators which highly couple the resolving power $\mathcal{R}=\nu/\delta\nu$ and $\eta_\mathrm{ch}$ to thin-film dielectric loss. The architecture presented in this paper addresses these limitations by eliminating the termination resistor and employing niobium coplanar waveguide resonators patterned directly on single-
crystal silicon, which fixes the resonator's internal quality factor by the silicon substrate property rather than by the loss tangent of a deposited film. The resolving power is set by the impedance ratio between the resonator and feedline. Electromagnetic and
circuit simulations of a ten-channel filterbank near 90~GHz at unity oversampling show $\mathcal{R}=1170$ and $\eta_\mathrm{ch}> 78\%$, with no significant trend in efficiency across channels. A ten-channel prototype, designed for $\mathcal{R}=92\pm5$ and $\eta_\mathrm{ch}=(81\pm3)\%$ over 90–106~GHz with a 560~nm interlayer based on simulations, was fabricated and optically characterized, yielding $\mathcal{R}=208\pm74$ and $\eta_\mathrm{ch}=(77\pm6)\%$. Measured $\eta_\mathrm{ch}$ well above the 50% termination limit, together with demonstrated impedance tuning of $\mathcal{R}$, validate the design principles of this filterbank spectrometer and establishes a route to high-efficiency, high-resolution on-chip spectrometer arrays.
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Fluid Dynamics
Is it true that no mathematical relation exists between the Navier-Stokes equations and the multifractal model?
John D. Gibbon and Dario Vincenzi
Contrary to accepted
turbulence folklore, which holds that no mathematical relation exists between the Navier-Stokes equations (NSEs) and the multifractal model (MFM) of Parisi and Frisch, we develop a theory that reconciles the MFM with Leray's weak solutions of Navier-Stokes analysis. From a combination of Euler invariant scaling and the NSEs set in a three-dimensional box of size $L$, we also derive the Paladin-Vulpiani inverse scale $\eta_{h,pav}$, which is related to the Reynolds number $\mathit{Re}$ by $L\eta_{h,pav}^{-1} = \mathit{Re}^{1/(1+h)}$, and which acts as a mediator between the two theories. This is achieved by considering $L^{2m}$-norms of the velocity gradient to find a correspondence between $m$ and the local scaling exponent $h$ in the multifractal model. The parameter $m$ acts as if it were the sliding focus control on a
telescope which allows us to zoom in and out on different structures. The range $1 \leqslant m \leqslant \infty$ is equivalent to $-2/3 \leqslant h_{min} \leqslant 1/3$, which lies precisely in the region where Bandak et al. (2022, 2024) have suggested that thermal noise makes the NSEs inadequate and generates spontaneous stochasticity. The implications of this are discussed.
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Fluid Dynamics
A Spherical Multipole Expansion of Acoustic Analogy for Propeller Noise
Felice Fruncillo, Paolo Luchini and Flavio Giannetti
This work develops a spherical-multipole expansion of the surface terms of an acoustic-analogy formulation, for the prediction of tonal noise from rotating propellers. The acoustic field is expressed through spherical multipoles, which separate source integrals from the observer dependence. This decoupling leads to computational efficiency: once the multipole coefficients are computed from blade geometry and aerodynamics, the sound field at any observer location is obtained by a simple evaluation of spherical harmonics and radial propagation factors, avoiding repeated integrations for each observer point. Moreover, this enables a straightforward radiated power calculation, without resorting to far-field pressure integrals. For hovering subsonic propellers, the results show a rapid convergence of the expansion. For each harmonic, the dominant radiation is accurately captured by the first two non-zero multipoles, corresponding to the leading symmetric and antisymmetric contributions with respect to the plane of rotation. To interpret the physical content of these leading terms, two simplified descriptions of the source integral are developed. The first is a lifting-surface formulation, suited to blades at small incidence, in which the thin-airfoil approximation allows to separate thrust-like loading, torque-like loading, and thickness contributions. The second is a lifting-line formulation, suited to high-aspect-ratio blades, in which the surface integral is reduced to spanwise integrals of compact sectional moments. The validity of the two formulations is assessed through comparisons of directivity, power distribution over harmonics and time-domain waveforms. Finally, both models are validated against experimental
datasets taken from the literature, showing excellent agreement for tonal directivity and blade-passing harmonics.
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Computational Physics · Cross-listed from math.NA
A stable and fast method for solving multibody scattering problems via the method of fundamental solutions
Yunhui Cai, Joar Bagge and Per-Gunnar Martinsson
The paper describes a numerical method for solving acoustic multibody scattering problems in two and three dimensions. The idea is to compute a highly accurate approximation to the scattering operator for each body through a local computation, and then use these scattering
matrices to form a global linear system. The resulting coefficient
matrix is relatively well-conditioned, even for problems involving a very large number of scatterers. The linear system is amenable to iterative solvers, and can readily be accelerated via fast
algorithms for the
matrix-vector multiplication such as the fast multipole method. The key point of the work is that the local scattering
matrices can be constructed using potentially ill-conditioned techniques such as the method of fundamental solutions (MFS), while still maintaining scalability and numerical stability of the global solver. The resulting
algorithm is simple, as the MFS is far simpler to implement than alternative techniques based on discretizing boundary integral equations using Nyström or Galerkin.
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Chemical Physics
Derivative Discontinuity in Many-Body Perturbation Theory and Chemical Potentials in Random Phase Approximation
Jiachen Li and Weitao Yang
We derive analytical expressions for chemical potentials within the random phase approximation (RPA), equivalently the $GW$ energy functional evaluated using non interacting Green's functions ($G_s$). The chemical potential is obtained using two formally equivalent approaches: a direct derivative of the total energy with respect to particle number, and a functional derivative via the chain rule through $G_s$, both validated with finite difference
benchmarks. We show that the functional derivative of the $GW$ correlation energy$\unicode{x2013}$i.e., the $GW$ correlation self energy$\unicode{x2013}$exhibits a discontinuity at integer particle numbers with finite jumps. This resolves the apparent inconsistency between accurate $GW$ quasiparticle energies and the large delocalization errors observed in RPA total energies, as standard $GW$ self energies neglect this nonanalytic behavior. Our results suggest that derivative discontinuities are a fundamental feature of correlation energy functionals, analogous to the known discontinuity in the exact exchange correlation energy.
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Atomic Physics · Cross-listed from cond-mat.quant-gas
Probing Coherent Many-Body Spin Dynamics in a Molecular Tweezer Array Quantum Simulator
Yukai Lu, Connor M. Holland, Callum L. Welsh et al. (+2 more)
Models of interacting
quantum spins are used in many areas of physics ranging from the study of magnetism and strongly correlated materials to
quantum sensing. In this work, we study coherent many-body dynamics of interacting
spin models realized using polar molecules trapped in rearrangeable optical tweezer arrays. Specifically, we encode
quantum spins in long-lived rotational states and use the electric dipolar interaction between molecules, together with Floquet
Hamiltonian engineering, to realize $1/r^3$ XXZ and XYZ models. We microscopically probe several types of coherent dynamics in these models, including
quantum walks of single
spin excitations, the emergence of
magnon bound states, and coherent creation and annihilation of
magnon pairs. Our results establish molecular tweezer arrays as a new
quantum simulation platform for interacting
quantum spin models.
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All authors Yukai Lu, Connor M. Holland, Callum L. Welsh, Xing-Yan Chen, Lawrence W. Cheuk
Chemical Physics · Cross-listed from quant-ph
Utility-scale quantum computational chemistry
Davide Castaldo and Markus Reiher
Chemistry and materials science are widely regarded as potential killer application fields for
quantum hardware. While the dream of unlocking unprecedented simulation capabilities remains compelling,
quantum algorithm development must adapt to the evolving constraints of the emerging
quantum hardware in order to accomplish any advantage for the computational chemistry practice. At the same time, the continuous advancement of classical wavefunction-theory methods narrows the window for a broad
quantum advantage. Here, we explore potential benefits of
quantum computation from the broader perspective of utility-scale applications. We argue that
quantum algorithms need not only enable accurate calculations for a few challenging, that is strongly correlated, molecular structures, that might be hard to describe with traditional methods. Instead, they must also support the practical integration of
quantum-accelerated computations into high-throughput pipelines for routine calculations on arbitrary molecules, ultimately delivering a tangible value to society.
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Fluid Dynamics · Cross-listed from math.DS
Parametric Spectral Submanifolds across Hopf Bifurcations with Applications to Fluid Dynamics
James King, Bálint Kaszás, Gergely Buza et al. (+2 more)
We investigate the persistence and regularity of spectral submanifolds (SSMs) in high-dimensional parametric dynamical systems undergoing a
Hopf bifurcation. By analyzing how resonances in the linearized spectrum near bifurcation points limit the existence and smoothness of SSMs, a phenomenon that has been mostly overlooked, we show that low-order Taylor coefficients of the SSM expansion and the associated reduced dynamics persist smoothly through the bifurcation. This analysis generalizes to any local bifurcation and provides a clear estimate of the parameter ranges over which a parametric SSM model can be justified, thus illustrating how globally the model can be extended despite the presence of resonances near criticality. We demonstrate these findings on multiple examples, including a data-driven SSM approach to the lid-driven cavity flow. For that problem, we construct a parametric SSM-reduced model that accurately captures the full transition to periodic dynamics and the critical Reynolds number. These results provide a mathematical foundation for robust data- and equation-driven model reduction of fluid flows across bifurcations, enabling an accurate prediction of nonlinear dynamics across critical parameter regimes.
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All authors James King, Bálint Kaszás, Gergely Buza, William Jussiau, George Haller
Plasma Physics
A finite-difference model for intense light interactions with dielectrics in the ultrafast ionization regime
Julia Apportin, Christian Peltz, Pavel Polynkin et al. (+3 more)
We present a computationally efficient model that describes the interaction of intense, ultrashort infrared
laser pulses with transparent materials in the strong ionization regime. The model is augmented with a detailed self-consistent description of the local response due to ionization and collisional
plasma dynamics. It incorporates the direct solution of Maxwell's equations without approximations and rigorous boundary conditions for the input pulse, allowing us to study the ultrafast formation of over-critical nanoscaled
plasmas in dielectric materials under the influence of intense tightly focused
laser pulses. We perform a scan of the parameter space, find unexpected optima regimes for different experientially relevant parameters, and explain these maxima based on spatiotemporal dynamics.
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All authors Julia Apportin, Christian Peltz, Pavel Polynkin, Misha Ivanov, Thomas Fennel, Anton Husakou