Nuclear Theory
Systematic Study of Proton, Two-Proton, Alpha, and Cluster Radioactivity Half-Lives based on the Deformed Gamow-like Model and Tabular Prior-data Fitted Network ($\mathrm{TabPFN}$)
Anqi Yang, Panpan Qi, Qingning Yuan et al. (+4 more)
A hybrid framework combining the deformed Gamow-like model ($\mathrm{DGLM}$) with the Tabular Prior-data Fitted Network ($\mathrm{TabPFN}$) is developed to improve half-life predictions for two-
proton emission,
proton emission, $\alpha$ decay, and cluster radioactivity. A total of 583 radioactive
nuclei are investigated, including 17 two-
proton emitters, 42
proton emitters, 498 $\alpha$ emitters, and 26 cluster emitters. Among the four considered models, $\mathrm{DGLM}^{b}+\mathrm{TabPFN}$ achieves the best overall performance, with $\sigma_{\mathrm{RMS}}=0.423$, corresponding to an improvement of approximately $82.2\%$ over $\mathrm{DGLM}^{b}$. The model parameters are optimized for each decay mode using the least-squares method. After introducing $\mathrm{TabPFN}$, the prediction errors for
proton emission and $\alpha$ decay are reduced by approximately $80.6\%$ and $87.6\%$, respectively. For $\alpha$ decay, the training, test, and overall RMSEs are 0.208, 0.305, and 0.240, indicating good generalization capability without evident overfitting. The model also reproduces the systematic
evolution of $\alpha$-decay half-lives and the shell-closure effect around $N=126$. These results demonstrate that combining $\mathrm{DGLM}$ with $\mathrm{TabPFN}$ significantly improves the accuracy and robustness of radioactive-decay half-life predictions while retaining the physical interpretability of the original model.
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All authors Anqi Yang, Panpan Qi, Qingning Yuan, Gongming Yu, Haitao Yang, Zhangyan Li, Yanbing Cai
Quantum Physics
Time rescaling for second-order feedback-based quantum optimization
Leticia Bertuzzi, João P. Engster, Evandro C. R. da Rosa et al. (+1 more)
Feedback-based
quantum algorithms recently gained
attention by demonstrating how
quantum computers can be used to solve optimization problems without resorting to hybrid
quantum-classical architectures. Recent progress made with Feedback-based
Algorithm for
Quantum Optimization (FALQON) variants significantly reduced the depth of the required
circuits. In this work, we merge the time-rescaled and second-order FALQON variants into a unified framework. The results show an important improvement over past modifications, reducing
circuit depth and allowing a more flexible choice of time-steps, while maintaining stable solutions. This FALQON variant makes it suitable for the NISQ era.
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All authors Leticia Bertuzzi, João P. Engster, Evandro C. R. da Rosa, Eduardo I. Duzzioni
Applied Physics
Liquid-Nitrogen Micropillar-Wick Cooling for Cryogenic Electronics: A Numerical Study of Thermal Performance and Capillary Dry-Out Limits
Felix Mende, Marcus Wislicenus, Dianping Jiang et al. (+2 more)
Cryogenic computing technologies are maturing rapidly, but heat removal remains a key challenge when increasing the device density and operating power. Two-phase evaporative cooling is a promising approach to solve this issue, because it can dissipate high heat fluxes while maintaining small temperature rises. Here, we numerically investigate
liquid-$\mathrm{N_2}$-filled silicon micropillar wicks as a capillary-fed thin-film evaporation concept for cryogenic electronics. The model combines Young-Laplace meniscus calculations, Hertz-Knudsen-Schrage evaporation, unit-
cell heat-transfer and
liquid-flow simulations, and an array-level thermal and capillary-flow model. For a representative geometry with a pillar diameter of $10\,\mu\mathrm{m}$, pitch of $24\,\mu\mathrm{m}$, and pillar height of $75\,\mu\mathrm{m}$ at an applied heat flux of $20\,\mathrm{W\,cm^{-2}}$, the predicted chip-temperature rise is approximately $2.7\,\mathrm{K}$. This is substantially below the estimated temperature rises for representative conduction cooling through an indium-interlayered copper heat sink and direct
liquid-$\mathrm{N_2}$ immersion. The corresponding predicted single-fed dry-out length is approximately $2.7\,\mathrm{mm}$, equivalent to an ideal double-fed coolable width of approximately $5.3\,\mathrm{mm}$. The results indicate that local thermal performance is favorable, whereas lateral scalability is primarily constrained by capillary dry-out. An approximate capillary-viscous scaling relation provides a compact framework for comparing dry-out limits across working fluids and related wick geometries and for identifying strategies to extend capillary-fed transport.
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All authors Felix Mende, Marcus Wislicenus, Dianping Jiang, Munehiro Tada, Lukas M. Eng
Physics and Society
Detectability limits of scaling laws
Alec Kirkley
Power law scaling relations between size and output are central to quantitative theories of cities, organisms, and other complex systems. Competing theories predict scaling exponents that differ by small fractions, but there is no existing theory for verifying whether a given
dataset can even distinguish exponents at the required resolution to address such discrepancies. Here we derive a resolution limit for scaling exponents, giving the smallest exponent difference that any method of analysis can detect. We find that the Hurst exponents governing the
evolution of systems' sizes and deviations from the scaling law determine how long a record of growing systems must be before it can separate competing scaling theories. Empirical results suggest that many available data panels are insufficient for reliable scaling model selection.
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High Energy Astrophysical Phenomena
A method for enhanced gamma-proton discrimination with imaging atmospheric Cherenkov telescopes
Jianling Liu and Hu Liu
Purpose: Very-high-energy gamma-ray astronomy is an important window to study the extreme astrophysical processes in the universe, and how to effectively distinguish between gamma
photons and background signals (mainly
protons) is a key technical challenge to realize very-high-energy gamma-ray detection. Spaceborne calorimeters record secondary particle spatial distributions, achieving a background rejection power of 10000-100000 near 1 TeV. Ground-based imaging Cherenkov
telescopes measure Cherenkov
photon angular distributions, yet they only reach a rejection factor of about 10 in this energy range, leaving substantial room for optimization. Methods: We use CORSIKA and sim_telarray to simulate H.E.S.S. detector responses.
Photon emission positions are reconstructed from Cherenkov shower images. Inspired by analysis techniques for space-borne calorimeter, we propose new observables derived from the transverse distribution of Cherenkov
photon emission positions to separate gamma-ray signals from
proton backgrounds. We employ a likelihood-ratio method to combine single-
telescope variables across multiple
telescopes and compare its performance with conventional Hillas-based analysis. Results: The results show that observables built from the transverse distribution of Cherenkov
photon emission positions are less sensitive to Cherenkov image size and outperform the Hillas width parameter for single-
telescope gamma-
proton discrimination. Furthermore, the likelihood ratio combining width yields substantially better performance than the conventional mean reduced scaled width: the improvement reaches roughly one order of magnitude near 1 TeV, and this enhancement remains above 50% for energies above 10 TeV.
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Accelerator Physics
Approximate solution of an adapted Bethe transport equation for electron scattering in foils
J.M. Corstens
A new semi-analytical model for electron scattering in foils is presented valid for thin foils and electron-beam kinetic energies up to roughly $100$ keV and from 20 keV at a dimensionless foil thickness of $20$, and higher energies for thinner foils. To perform calculations, an approximate solution is constructed by Hankel transforms of an adapted Bethe transport equation for electron scattering. The Wentzel differential cross section is used in the Bethe transport Eq. and resulting integrals are solved analytically or approximated. These approximate solutions of the transport Eq.'s were compared to the Goudsmit-Saunderson solutions in gold, for thin samples with dimensionless thicknesses $\lambda=5,10,20$. We also compare to the Kawrakow \cite{Kawr} model, which uses the small angle approximation. We show that in the regime of $20$ to $100$ keV beam energies, our model performs better than Kawrakow's model and this is opposite above about 100 keV. Exactly, some angularly distributed beams and the influence of energy loss of the beam can be simulated with our model.
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Strongly Correlated Electrons
Reformulating Pfaffian Quantum Monte Carlo with the Hybrid Monte Carlo formalism
Thomas Hauschild, Lin Wang, Finn L. Temmen et al. (+1 more)
Pfaffian
quantum Monte Carlo extends auxiliary field methods to anomalous fermionic
Hamiltonians, opening access to pairing systems and Hubbard–Stratonovich decompositions that are unavailable in determinant formulations. We show that this flexibility can be combined with the global updates of Hybrid Monte Carlo (HMC), leading to an
algorithm scaling as $\mathcal{O}(N_\tau L^3)$, similar to its determinant
quantum Monte Carlo (DQMC) counterpart without pseudofermions. The central observation is that the molecular dynamics force depends only on the magnitude of the Pfaffian weight, which admits a determinant representation and leads to a simplified force expression. This construction also yields unequal-time Majorana correlators at essentially no additional cost. We demonstrate the method for the interacting Kitaev chain using the imaginary and symmetric Majorana hopping channel. The resulting noncommuting auxiliary-field bond operators are treated through an even-odd decomposition. Their block structure permits an analytic reduction to a sparse effective interaction
matrix of bandwidth two and allows explicit force expressions. Results agree with exact diagonalization and resolve low-energy modes localized at opposite boundaries, together with their increasing overlap near the topological transition of the non-interacting system. These findings establish HMC as an efficient sampling framework for Pfaffian auxiliary-field simulations.
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All authors Thomas Hauschild, Lin Wang, Finn L. Temmen, Thomas Luu
Mesoscale and Nanoscale Physics
Spatially resolved quantum magnetometry and stray-field reconstruction of permalloy microdisks using boron-vacancy centers in hexagonal boron nitride
Peiting Wen, Shuyu Wen, Jiang Qu et al. (+13 more)
Transferable hexagonal boron nitride (hBN) hosting negatively charged boron-vacancy (VB$^{-}$)
spin defects offers a versatile platform for integrated
quantum magnetometry, yet quantitative imaging of
magnetic microstructures remains challenging. Here, we integrate a transferred hBN flake with a 4 $\mu$m-diameter permalloy (Py = Ni${81}$Fe${19}$) microdisk and perform spatially resolved optically detected
magnetic resonance measurements at room temperature. An applied in-plane
magnetic field distorts the
vortex-state magnetization, generating edge-localized
magnetic surface charges and pronounced stray-field signatures at opposite disk edges. By referencing each pixel to its local zero-field splitting and correcting for a residual out-of-plane bias field, we quantitatively reconstruct the out-of-plane stray-field distribution, revealing peak fields of approximately 11.2 mT. An edge-charge model reproduces the spatial distribution and amplitude of the reconstructed field, linking the ODMR response to the field-driven
evolution of the
vortex state. These results establish transferred hBN VB$^{-}$ sensors for quantitative magnetometry of
magnetic microstructures.
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All authors Peiting Wen, Shuyu Wen, Jiang Qu, Zeling Xiong, Katrin Schultheiss, Slawomir Prucnal, Artur Erbe, Kenji Watanabe, Takashi Taniguchi, Jürgen Lindner, Jürgen Fassbender, Manfred Helm, Shengqiang Zhou, Ruslan Salikhov, Helmut Schultheiss, Yonder Berencén
Quantum Physics
Discrete semiclassical theory of quantum-thermal escape
Luca Salasnich and Cesare Vianello
The dissipationless
quantum-thermal escape rate from a metastable well is often written as a Boltzmann average of the Hill-Wheeler flux over a continuum of energies. This continuum treatment diverges exponentially at low temperature, because it pairs the
quantum partition function of the well with a classical flux integral. Retaining the discrete nature of the quasibound spectrum removes the divergence exactly, and the resulting rate is obtained in closed form on both sides of the crossover temperature $T_0$. Evaluating a uniform Kemble transmission probability on Bohr-Sommerfeld levels further removes the
parabolic-barrier error and recovers the WKB decay rate of the lowest resonance at zero temperature. Benchmarked against the resonances of cubic and quintic potentials, obtained by complex scaling, this uniform semiclassical rate stays within $9\%$ of the exact one over eleven orders of magnitude. Below $T_0$, the rate rises above its zero-temperature plateau with the level spacing as activation energy, and the plateau ends at a temperature $T_1$ noticeably below $T_0$. In an isolated well, whose levels are not replenished, the thermal rate is only the initial slope of a decay which ceases to be single exponential at $T_1$, while at $T_0$ the initial escape moves from tunneling inside the well to the barrier top. We discuss implications for Josephson junctions, single-electron pumps, and
nuclear burning in dense
stellar matter.
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Strongly Correlated Electrons
Resonant spin mode from retarded relaxation
J. Beater and G.S. Uhrig
In ultrafast
spin dynamics additional modes in the THz range appear which cannot be captured by conventional Landau-Lifshitz equations. Extending these equations by further time derivatives (inertial Landau-Lifshitz-Gilbert equation) solves the issue only partly. Here we suggest to explain these modes by retarded Lindbladian relaxation. In spite of the simplicity of this phenomenological approach the agreement with the experimental data is promising: physically plausible parameters describe the position and the large width of these resonances. The salient feature of several almost equidistant resonance peaks is in-line with experimental evidence as well.
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Instrumentation and Detectors
A compact fibre-coupled active beamstop for fast time-resolved monitoring of synchrotron X-ray beams
Friedjof Tellkamp, David von Stetten and Martin Kollewe
We have developed a compact fibre-coupled active beamstop for simultaneous interception and time-resolved monitoring of the direct X-ray beam in synchrotron diffraction experiments. The complete beamstop tip has a maximum transverse dimension of 1 mm and incorporates a 700 $\mu$m-wide Ce:YAG scintillator. The scintillator converts the intercepted X-rays into visible light, which is transported through a multimode optical fibre to a silicon photodiode at the bottom of the blade that is connected to a dedicated fast amplifier electronics. Tests with a pulsed
laser yielded a system decay time of 69.4 ns, consistent with reported luminescence decay times for Ce:YAG. Measurements at the P14.EH2 end station of PETRA III demonstrated the detection of individual bunch signals separated by 192 ns in the 40-bunch operating mode. The active beamstop also provided an in-situ timing signal for synchronising an experimental sequence with the approximately 190 $\mu$s transmission window of a mechanical X-ray chopper. The device therefore combines a compact obstruction of the direct beam with fast monitoring of X-ray timing and flux during diffraction data acquisition.
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Physics and Society
Multilayer Analysis of the Global Trade Network
Chenyang Li, Leonardo Brogi, Andrea Civilini et al. (+3 more)
Global trade is more than a single network of aggregate flows. Beneath the observable exchange of products among economies lies a complex multilayer structure, formed by thousands of product-specific trade relationships that differ in their similarity, interdependence, and temporal
evolution. Using the CEPII's BACI database, which records bilateral product-level trade flows between economies, we represent the global trade network from 1995 to 2024 as a temporal multilayer network, with economies as nodes and directed weighted trade flows as edges. To investigate product-level organisation and cross-layer similarity, temporal structural change, and the structural role of individual economies, we introduce a random-walk-based similarity measure that provides a unified framework for comparing weighted and directed trade layers. Our results show that the global trade network remains relatively stable over short periods but undergoes gradual structural change over longer timescales. We also find that similarity-based product communities only partially align with the official product taxonomy, indicating that products assigned to the same official category do not necessarily exhibit similar trade-network structures. Finally, we show that an economy's structural influence is not always determined by its trade volume. These results highlight the value of multilayer network analysis for revealing patterns in global trade that remain hidden at the aggregate level.
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All authors Chenyang Li, Leonardo Brogi, Andrea Civilini, Piero Mazzarisi, Nicola Perra, Vito Latora
Superconductivity
Digital-analog concept for superconducting perceptron-like neural networks
Andrey E. Schegolev, Vsevolod I. Ruzhickiy, Georgy I. Gubochkin et al. (+7 more)
A promising route to superconducting artificial neural networks is a hybrid digital-Analog architecture that combines digital single-flux-
quantum (SFQ) communication with compact Analog nonlinear processing. The study focused on the dynamic conversion of a discrete signal passing through a digital-to-Analog-to-digital (DAD) converter, in which the role of the Analog
cell was performed by a $\Sigma$-
neuron with a nonlinear transfer function – the basic
cell of perceptron-like neural networks. Furthermore, the DAD converter, the elementary functional block of the hybrid architecture, combines a digital-to-analog converter (DAC) and an Analog-to-digital converter (ADC), and re-encodes the Analog $\Sigma$-
neuron waveforms as an SFQ pulse sequence.
Circuit-level simulations demonstrate how input values encoded by SFQ pulse trains are converted into analog signal levels, transformed by the $\Sigma$-
neuron, and mapped back to pulse-based outputs. As a key experimental step, we fabricated and characterised a redesigned $\Sigma$-
neuron and measured a sigmoid-like transfer characteristic suitable for activation-function implementation. The extracted response was incorporated into system-level simulations to assess the influence of realistic device parameters on the conversion process. We delineate the operating-range matching requirements for the DAC,
neuron, and ADC blocks, supporting the feasibility of the proposed interface as a building block for perceptron-like superconducting neural networks with digital inputs and outputs. Finally, we developed two perceptron networks, one using a mathematical sigmoid activation and the other the measured $\Sigma$-
neuron transfer characteristic, which reached classification accuracies of $97.0\%$ and $91.9\%$, respectively, on the MNIST handwritten digit
dataset.
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All authors Andrey E. Schegolev, Vsevolod I. Ruzhickiy, Georgy I. Gubochkin, Alexander S. Ionin, Ivan A. Nazhestkin, Mikhail Y. Fominskii, Lyudmila V. Filippenko, Igor I. Soloviev, Maxim V. Tereshonok, Nikolay V. Klenov
Instrumentation and Methods for Astrophysics
Combining astrometry with pulsar timing: the first joint analysis of very low frequency gravitational waves
Lorenzo Filipello, William Beordo, Volodymyr Akhmetov et al. (+2 more)
The pHz to sub-nHz GW regime remains largely unexplored but is crucial for mapping the early inspiral stage of SMBHBs and probing early-Universe physics. Astrometry and
pulsar timing offer orthogonal and deeply complementary secular observables to investigate this frequency band. We aim to present the first joint data analysis combining real astrometric proper motions with binary
pulsar timing, to search for and constrain continuous gravitational waves (CWs) sourced by SMBHBs in the ultra-low-frequency regime ($10^{-12} \le f_{GW} \le10^{-9} Hz$). We employ a
Bayesian model selection and upper limit estimation framework to combine apparent proper motion displacements of $\sim 1.5 \times 10^6$
quasars from the
Gaia CRF3 catalog with the line-of-sight orbital period derivatives ($\dot{P}_b$) of 11 high-precision binary
pulsars. To prevent spurious detections, we heavily model instrumental and astrophysical systematics: we propagate the
Galactic potential uncertainty for
pulsars via Monte Carlo simulations and perform a Vector Spherical Harmonics (VSH) decomposition up to the octupole order (l=3) for
quasars. We find no statistically significant evidence for a CWs signal in the joint analysis ($\ln B_{joint} = -0.42 \pm 0.03$). In the absence of detection, we set the tightest constraints to date on CW strain in the pHz band, yielding a 95% upper limit of $h_0\le6.4x10^{-11}$ at a reference frequency of $f_{ref} = 4 \times 10^{-10}$ Hz. The combined
dataset achieves full sky coverage and improves single-
dataset upper limits by 20%-30%. Combining orthogonal observables successfully breaks spatial degeneracies intrinsic to isolated searches. Furthermore, forecasts from inj.-rec. indicate that with the extended temporal baseline and reduced uncertainties of the upcoming
Gaia DR4, this joint framework is poised to break the $h_0 < 10^{-11}$ upper limit barrier for sub-nHz CWs.
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All authors Lorenzo Filipello, William Beordo, Volodymyr Akhmetov, Mariateresa Crosta, Mario Gilberto Lattanzi
Astrophysics of Galaxies
ALMA Chemical Evolution (ACE) survey: an overview – extending dust and gas inference to low metallicities at cosmic noon
Irene Shivaei, Gergő Popping, Leindert A. Boogaard et al. (+13 more)
The
baryon cycle governs the exchange of gas, metals, and
dust between
galaxies and their environments, but simultaneous constraints on these constituents remain scarce beyond z~1. The ALMA Chemical
Evolution (ACE) survey is a Cycle 11 ALMA Large Program designed to address this by studying the molecular gas,
dust, and metal content of sub-
solar metallicity at
cosmic noon. ACE consists of CO(3-2) and
dust continuum observations of 25
galaxies at z=2.0-2.5 with robust gas-phase
metallicity measurements spanning ~35% to 83% of
solar metallicity. The survey approximately doubles the number of unlensed main-sequence
galaxies at z>1 with CO,
dust-continuum and
metallicity measurements and extends such studies to almost an order of magnitude lower
stellar masses and
metallicities than previous surveys. The ACE observations yield 17 CO detections and 17 Band 7 continuum (rest-frame ~270um) detections. CO detectability correlates most strongly with
metallicity and
stellar mass, while
dust continuum detectability is more closely linked to
star formation rate (SFR) and infrared luminosity. Using the ACE measurements, we derive a new empirical scaling relation linking CO(3-2) luminosity to
stellar mass, SFR, and
metallicity, providing a practical
benchmark for estimating molecular gas content in low-mass, low-
metallicity galaxies. The survey reveals several particularly intriguing systems, including some of the lowest-
metallicity CO and
dust detections currently known at z>1,
galaxies with extreme gas and
dust fractions, and systems exhibiting offsets between
stellar,
dust, and molecular gas emission. ACE provides the first comprehensive view of the interplay between molecular gas,
dust, metals, and
star formation in sub-
solar metallicity galaxies at
cosmic noon, enabling direct tests of models for
baryon cycling, chemical enrichment, and
dust evolution during the peak epoch of
galaxy assembly.
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All authors Irene Shivaei, Gergő Popping, Leindert A. Boogaard, Alexandra Pope, Ivanna Langan, Roxana Popescu, Nikki N. Geesink, Manuel Solimano, Caitlin M. Casey, Maximilien Franco, Melanie Kaasinen, Bahram Mobasher, Desika Narayanan, Pablo G. Pérez-González, Naveen Reddy, Ryan Sanders
Quantum Physics
Experimental Measurement and Theoretical Analysis of Energy Relaxation Rates of an Interacting Two-Qubit System on a D-Wave Quantum Annealer
Yusei Amano, Sorato Suzuki, Hiroki Kuji et al. (+3 more)
In D-Wave
quantum annealers, various properties of the ground state have been clarified, whereas the correspondence between theory and experiment for energy relaxation rates in multiqubit excited states remains insufficiently understood. Here, we measured the energy relaxation rates of the first excited states in single-
qubit systems and interacting two-
qubit systems using a D-Wave
quantum annealer. We analyzed the measured relaxation rates using a Gorini-Kossakowski-Sudarshan-Lindblad master equation with independent local $\sigma^{\,\,z}$-type noise channels. The calculated relaxation rates reproduced the overall trends observed experimentally, supporting the model at a qualitative level. We then used the relaxation rates measured for the uncoupled single-
qubit systems to calibrate the local relaxation parameters and predict the relaxation rates of the interacting two-
qubit systems. The predicted rates remained within a factor of approximately four of the measured rates. These results show that the relaxation measurements on individual
qubits can provide a practical estimate of relaxation in small interacting
quantum systems and may help clarify relaxation mechanisms in programmable
quantum annealers.
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All authors Yusei Amano, Sorato Suzuki, Hiroki Kuji, Tetsuro Nikuni, Takashi Imoto, Yuichiro Matsuzaki
Astrophysics of Galaxies
Hierarchical Hub Formation in Mon~R2: Evidence for Cloud-to-core Gas Flows
L. K. Dewangan, O. R. Jadhav, A. K. Maity et al. (+2 more)
We present a multi-scale kinematic study of the hub-filament system in Mon R2 using JCMT $^{13}$CO(3–2) and ALMA C$^{18}$O(1–0) observations to investigate how molecular gas converges toward the central hub and connects across cloud-to-core scales. The $^{13}$CO data reveal several velocity-coherent filaments with diverse position angles converging toward the central region hosting massive
stars and
stellar clusters, where distinct velocity components become spatially superposed. Two dominant velocity regimes at $\sim$8.8–10.2 and $\sim$10.4–11.8 km s$^{-1}$ are identified, with their velocity separation decreasing toward the central hub. The position–position–velocity and longitude–velocity maps of the $^{13}$CO emission exhibit a butterfly/X-shaped morphology, consistent with converging motions. A phenomenological rotating-and-infalling envelope model reproduces the longitude-velocity morphology, indicating that rotation and infall may contribute to the observed kinematics, although the model does not uniquely identify the underlying mechanism. At higher resolution, the ALMA C$^{18}$O observations resolve the molecular gas into multiple velocity-coherent filaments spanning $\sim$8–13 km s$^{-1}$, with distinct kinematic domains at $\sim$9–10.5, 10.5–11.5, and 12–13 km s$^{-1}$ converging toward the hub. The ALMA and JCMT position-velocity diagrams show consistent velocity structures across their respective spatial scales, with the ALMA-resolved features embedded within the broader molecular-gas velocity field traced by JCMT, demonstrating a multi-scale kinematic connection. These results support a hierarchical picture in which converging flows and filamentary
accretion contribute to hub growth and ongoing
star formation in Mon R2, while other dynamical processes may also contribute to the observed kinematics.
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All authors L. K. Dewangan, O. R. Jadhav, A. K. Maity, Saurabh Sharma, Ram K. Yadav
Atmospheric and Oceanic Physics
Surface Stokes drift from compact drifting wave buoys
Alexey S. Mironov, Fabrice Collard, Gwenaele Jan et al. (+1 more)
Surface Stokes drift depends strongly on the energy and directions of short waves, which are incompletely resolved by routine wave observations. We derive surface Stokes drift vectors from wave measurements collected by compact drifting buoys during three deployments in the North-East Atlantic and the Alboran Sea. The calculation uses vertical-acceleration spectra and first directional
Fourier moments, which describe the mean wave direction and directional concentration at each frequency; it accounts for the Doppler shift caused by buoy motion relative to the water and adds a calibrated high-frequency tail above an intrinsic frequency of 0.7 Hz. Across 13,139 records, the median estimated speed is 0.081 m/s at a median wind speed of 6.8 m/s. Over the measured band of 0.04-1 Hz, accounting for wave directions reduces the magnitude by a median 39% relative to the unidirectional assumption. The median ratio of the parameterised tail magnitude above 0.7 Hz to the total estimated magnitude is 0.37. Comparisons with WAVEWATCH III and Copernicus Marine MFWAM show strong covariation and similar wind-dependent differences from the buoy-derived estimates. On the station-matched sample from the two Atlantic deployments, WAVEWATCH III directional spectra indicate that these differences within the compared band arise mainly from spectral levels rather than from net directional reduction. The observations provide constraints for model evaluation; the contribution of the unresolved short waves remains sensitive to the assumed spectral tail and its directional spreading.
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All authors Alexey S. Mironov, Fabrice Collard, Gwenaele Jan, Bertrand Chapron
Fluid Dynamics
Periodic Neural Mapping for Unsteady Rotor-Blade Pressure and Aeroelastic Load Prediction
Lionel Salesses, Joachim Dominique, Tariq Benamara et al. (+2 more)
Accurate prediction of unsteady aerodynamic loads remains a major challenge in turbomachinery design. High-fidelity Computational Fluid Dynamics (CFD) simulations are expensive, while aeroelastic Quantities of Interest (QoI) depend sensitively on the temporal
evolution of the pressure field. This work introduces periodic
Fourier Neural Mapping (p-FNM), a neural-operator framework for predicting unsteady pressure distributions on turbine rotor blades simulated using the chorochronic numerical hypothesis. The architecture embeds temporal periodicity into the model and learns a continuous mapping from operating conditions and time to pressure fields. Unlike sequential latent-space approaches, p-FNM predicts pressure fields independently at any time, avoiding error accumulation while preserving temporal continuity. The model is evaluated on a database of unsteady rotor-blade simulations and compared with a reduced-order baseline based on a variational autoencoder and recurrent neural network, refered as the Temporal Prediction Model (TPM). Performance is assessed for pressure fields and Generalized Aerodynamic Forces (GAFs), the primary aeroelastic QoI. Across all training
datasets, p-FNM consistently outperforms TPM. On the largest
dataset, p-FNM achieves a pressure-field mean absolute percentage error of 0.46% and a GAF-magnitude prediction error of 4.42%, corresponding to improvements of 60.7% and 77.6%, respectively. The minimum weighted phase error reaches 0.060 rad, demonstrating accurate preservation of the temporal characteristics of the aerodynamic response. The results show that GAF prediction is more challenging than pressure-field prediction and that temporal coherence is critical for accurately predicting spectral aerodynamic quantities. These findings demonstrate the potential of periodic neural operators for reduced-order modeling and aeroelastic analysis in turbomachinery.
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All authors Lionel Salesses, Joachim Dominique, Tariq Benamara, Théo Flament, Franck Mastrippolito
Mesoscale and Nanoscale Physics
Transport statistics and thermoelectric performance of Hofstadters butterfly
Friedemann Queißer and Gernot Schaller
We investigate electrons subject to a
magnetic field that may tunnel along a square
lattice and additionally to two electronic leads. Using non-
equilibrium Greens functions we evaluate the transmission and from that particle and energy currents and zero-frequency noise of the setup. We identify sweet spots for which the transmission reaches unity over broad frequency windows – carried by topologically protected boundary modes that are quite robust against local fluctuations of on-site energies. These transmission plateaus can be exploited for the implementation robust current standards, clocks and thermoelectric devices.
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Mesoscale and Nanoscale Physics
Floquet-spin-orbit compensation and flat- and quadratic-band contact in the $\alpha$-$T_3$ lattice
Imtiaz Khan, Muzamil Shah, Reza Asgari et al. (+1 more)
We investigate Floquet–
spin-orbit compensation in the three-band $\alpha$-$T_3$ system, which interpolates between
graphene at $\alpha=0$ and the dice
lattice at $\alpha=1$. By tuning the interplay between an off-resonant circularly polarized optical field and intrinsic
spin–orbit coupling, we identify three distinct pairwise band-degeneracy conditions in the quasienergy spectrum: (i) valley–
spin degeneracy, (ii)
spin–band degeneracy, and (iii) flat–dispersive band degeneracy. The flat band is not an artifact of a two-band reduction but rather an exact property of the continuum
Hamiltonian at this compensation point, where the complete three-band
Hamiltonian supports a momentum-independent dark state. A winding-two low-energy
Hamiltonian and a finite-momentum Berry-
curvature maximum, whose radius scales as the square root of the detuning, emerge from detuning this contact. We further show that the intrinsic transverse thermoelectric response encodes these spectrum patterns. The flat- and quadratic-band degeneracy can be predicted for $0<\alpha<1/2$ because the two response scales linked to the linear contacts have a monotonic ratio independent of the common
spin–orbit energy scale. This allows an inverse determination of $\alpha$ and of the common spectral scale. The analytical results are confirmed by full three-band Kubo calculations, which also define the regime in which this inverse characterization is still observable. These results connect an experimentally accessible, Berry-
curvature-sensitive thermoelectric response to tunable Floquet–
spin–orbit band geometry.
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All authors Imtiaz Khan, Muzamil Shah, Reza Asgari, Gao Xianlong
General Relativity and Quantum Cosmology
Exact DeWitt kernels in Lorentzian quantum cosmology
Hiroki Matsui
The DeWitt boundary condition can be implemented in the Lorentzian path integral of minisuperspace
quantum cosmology by summing only over non-singular paths. In this paper, we present a general definition of the resulting DeWitt kernels, along with specific rules for their construction, and evaluate them rigorously. The lapse integral over the positive half-line yields the Dirichlet Green function of the Wheeler–DeWitt operator, whereas the integral over the whole real line yields the Dirichlet group-averaging kernel; both vanish when either endpoint lies at the singularity. Since the minisuperspace actions are at most quadratic, all lapse integrals are performed in closed form without saddle-point approximations. We obtain the kernels for the closed universe without cosmological constant, for the flat de Sitter universe, and, in terms of Airy functions, for the closed and open de Sitter universes. Throughout, the DeWitt condition is imposed as the boundary condition at the singularity, which selects a self-adjoint constraint operator on the half-line and fixes the kernels uniquely, including their normalization.
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Soft Condensed Matter
Tunable parametric vibrations in fluid ferroelectric fibres
Alexander Dieter-Jarosik, Hajnalka Nádasi, Rachel Tuffin et al. (+2 more)
Freely suspended ferroelectric-nematic fibres combine 1D fluidity with macroscopic spontaneous polarisation. Under alternating electric fields, we observe a sequence of dynamical states, from subthreshold pulsations to polarity-dependent axial flow, and sustained transverse oscillations. We show that the oscillatory state arises from a parametric instability of a
liquid string whose effective tension is dominated by the electrical polarisation-field coupling contribution. A Floquet model incorporating finite-time polarisation switching captures the observed resonance tongues, modal selection, and square-wave response. These results establish ferroelectric-nematic fibres as electrically programmable fluid resonators coupling polar order and interfacial flow with nonlinear vibration.
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All authors Alexander Dieter-Jarosik, Hajnalka Nádasi, Rachel Tuffin, Melanie Klasen-Memmer, Alexey Eremin
Quantum Physics
Global Entanglement Quantification via Classical Shadows
João P. Engster and Eduardo I. Duzzioni
Detecting and characterizing
quantum correlations are tasks of great relevance in
quantum information. More specifically, quantifying the amount of multipartite
entanglement is a known difficult task, even for pure states. To this end, several
entanglement measures have been proposed, although there is currently no universal manner to do so. In this work, we propose the classical shadows technique to measure the generalized global
entanglement introduced in Phys. Rev. A 74, 022314. This particular multipartite
entanglement quantifier $E_G^{(n)}$ relies on the linear
entropies of all $n$-
qubit partitions of a state. As the linear
entropy can be written in terms of a complete set of observables of the subsystem, we employ classical shadows to estimate many observables with fewer measurements. We simulate the quantification of $E_G^{(n)}$ for well-known entangled states and for random states, comparing shadow estimations and grouping techniques. Our results show a clear advantage of classical shadows over direct estimation approaches, indicating that it can be a useful tool to quantify
entanglement without the need to reconstruct the density operator of the whole system.
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Cosmology and Nongalactic Astrophysics
A note on oscillons: non-negligible metric fluctuations during preheating
Daniel del-Corral, Paolo Gondolo, K. Sravan Kumar et al. (+1 more)
The dominant
lattice approach to post-inflationary preheating and oscillon formation evolves an inhomogeneous inflaton field on a spatially homogeneous Friedmann-Lemaître-Robertson-Walker background, whose expansion is sourced by a volume-averaged energy density, while metric perturbations are neglected. We examine the consistency of this approximation with General Relativity. Using the linearized Einstein constraints, we show that the suppression of the Bardeen potential, characteristic of slow-roll inflation, disappears during preheating: once the first slow-roll parameter becomes of order unity, the metric and inflaton fluctuations enter at the same perturbative order. We further show that the scalar-field equation evolved in the fixed-FLRW prescription omits leading-order contributions generated by metric fluctuations. We then derive the proper-volume average of the ADM
Hamiltonian constraint and show that it does not reduce to the Friedmann equation used in
lattice simulations: the exact averaged constraint contains additional contributions from the spatial
curvature, the variance of the local expansion, the shear, and metric corrections to the local energy density. Finally, we illustrate numerically, for Starobinsky and $\alpha$-attractor models, that the metric contribution becomes comparable to the scalar-field contribution during the amplification stage. These results directly affect the standard
lattice description of oscillon formation and motivate numerical relativity as a consistent framework for the nonlinear preheating problem.
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All authors Daniel del-Corral, Paolo Gondolo, K. Sravan Kumar, João Marto
Optics
Programmable Intrinsic Circularly Polarized Emission
Yujie Jiao, Zhenqin Li, Yide Chang et al. (+11 more)
Circularly polarized luminescence (CPL) is central to
chiral photonics, yet programming circularly polarized emission at the nanoscale remains challenging. Here, we program intrinsic CPL at its microscopic origin in
laser-written all-inorganic perovskite nanocrystals embedded in glass. High-resolution transmission electron microscopy reveals a core-shell-like variation in interplanar spacing associated with intrinsic CPL, consistent with torsional
lattice distortion. The torsional
lattice distortion breaks inversion
symmetry, while density functional theory calculations show that it lifts the
spin degeneracy of the band-edge electronic states. Power-dependent measurements further reveal a transition from birefringence-mediated circular polarization to intrinsic CPL, accompanied by the emergence of a distinct core-shell-like
lattice distortion in the nanocrystals. By tuning the incident linear polarization angle and focal depth, we deterministically control both the handedness and magnitude of the intrinsic CPL, with |glum| of approximately 4 ^ 10^-3. These results show that programmable intrinsic CPL originates from the structural and electronic properties of the emitting nanocrystals, enabling circularly polarized emission to be controlled at its microscopic origin and spatially encoded within a monolithic material.
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All authors Yujie Jiao, Zhenqin Li, Yide Chang, Yongsen He, Xiaoyu Sun, Wei Lyu, Jiayu Ding, Zhaolin Zhong, Puxin Yang, Chi Chen, Bangjie Song, Min Qiu, Yanming Wang, Siying Peng
Optics
Frequency-swept Brillouin spectroscopy
Lin Kang, Shahrin Jahan Jaima and Jitao Zhang
Spontaneous Brillouin microscopy provides non-contact access to the viscoelastic properties of materials. Standard measurements typically utilize a single-wavelength continuous-wave
laser to illuminate a specimen and excites a spontaneous Brillouin scattering signal, which is then recorded by a spectrometer. Existing Brillouin spectrometers are mostly built around either a scanning Fabry-Pérot etalon or a virtually imaged phased array (VIPA) etalon. While performing well, these setups are bulky and demand significant optical expertise to construct and maintain. Here, we propose a new approach to conducting Brillouin spectroscopy. In this approach, a frequency-swept
laser excites a series of Brillouin spectra with incrementally shifted central frequencies, while a frequency picker, consisting of a narrow bandpass filter and a highly sensitive single-
photon detector, sequentially records each spectral component to reconstruct the full spectrum. We demonstrate that the frequency-swept Brillouin spectroscopy can run under shot-noise limited condition using standard samples. Compared with conventional spectrometers, our system features a much more compact design for portable applications and holds potential for rapid mechanical imaging through multiplexing.
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Quantum Physics
Weighted Quantum Signal Processing: Low-Depth Polynomial Approximation with Applications to Kolmogorov-Arnold Networks
Rohit Sarma Sarkar, Rupayan Bhattacharjee, Elias F. Combarro et al. (+5 more)
Quantum Signal Processing is a powerful
quantum framework for generating and approximating univariate
polynomials. However, QSP is often limited by
circuit-depth bottlenecks and parity constraints on the class of realizable
polynomials. In this work, we introduce Weighted
Quantum Signal Processing, an extension of QSP in which a weight function is assigned to the central rotation operator. This formulation provides a deeper understanding of QSP, which emerges as the special case of WQSP with unit weights. The choice of weights determines the structure and expressive capabilities of WQSP
circuits. When the weights are natural numbers greater than one, WQSP reduces to a pruned version of QSP, revealing parameter redundancies in the standard framework. Through appropriate selection of integer weights, WQSP achieves linear-to-exponential reductions in the number of parameters required to realize arbitrary bounded univariate
polynomials while preserving approximation quality. For generic weights, we establish corresponding approximation error bounds and show that, in many cases, the approximation is exact. We analyze WQSP from both a deterministic perspective, where
polynomial generation is formulated as the solution of a linear system, and a
quantum machine learning perspective, where WQSP serves as a structured and expressive
quantum learning model. We further employ this learning framework to parameterize learnable activation functions in Kolmogorov–Arnold Networks for multivariate function approximation. Our results show that WQSP provides a compact, flexible, and theoretically grounded framework for realizing arbitrary univariate
polynomials while requiring significantly fewer trainable parameters than conventional QSP. This yields expressive and parameter-efficient neural architectures, highlighting the potential of WQSP as a scalable primitive for
quantum-enhanced machine learning.
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All authors Rohit Sarma Sarkar, Rupayan Bhattacharjee, Elias F. Combarro, Michele Grossi, Lirandë Pira, Carmen G. Almudéver, Sergi Abadal, Eduard Alarcon
Quantum Physics
Giant-Atom-Induced High-Order Output Zeros in a Coupled-Cavity Array
Mengxue Li, H. Z. Shen, H. D. Liu et al. (+1 more)
Coherent perfect absorption, zero transmission and zero reflection are several scattering phenomena governed by interference engineering in Hermitian and non-Hermitian systems. Higher-order coherent perfect absorption can significantly broaden the absorption bandwidth, while existing implementations rely on scattering zero degeneracy induced by exceptional points or additional momentum-dependent phase delays introduced in incident waves. We propose a scheme where a
giant atom couples to a one-dimensional coupled-cavity array at two spatially separated sites. The spatially separated coupling configuration of the
giant atom generates tunable nonlocal interference phases that dominate the scattering interference process. We further investigate the zero-reflection and zero-transmission behaviors under single-sided incidence. Remarkably, we find that for certain parameter choices, zero transmission can persist over the entire propagating band, rather than being restricted to a single momentum. Our results reveal that the
giant-atom interference mechanism enables bandwidth-enhanced coherent perfect absorption and bandwidth-enhanced zero transmission in the absence of exceptional points and incident momentum-dependent phase delays. Our work provides a physical route for coherent wave manipulation in coupled-cavity
quantum networks.
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All authors Mengxue Li, H. Z. Shen, H. D. Liu, Gangcheng Wang
Materials Science
Validation of an Ab Initio-Informed Electronic Stopping Model for Large-Scale Atomistic Simulations
Glen P. Kiely, Rafael Nuñez-Palacio and Andrea E. Sand
Accurately modeling nonadiabatic electronic energy dissipation in atomistic simulations of radiation damage remains a key challenge. Existing models often rely on arbitrary thresholds and neglect trajectory-dependent, band-structure, and nonlinear effects. A model developed by Tamm et al. (\href{https://doi.org/10.1103/PhysRevLett.120.185501}{doi:10.1103/PhysRevLett.120.185501}) offers a nonempirical description of electronic dissipation for atomistic simulations, but has not been directly benchmarked in the electronic stopping regime. We present the first such
benchmark via the comparison of atomistic simulations with experimental ion transmission experiments. The model accurately captures the magnitude and trajectory-dependence of the predicted energy losses. These results support the reliability of the model for predictive large-scale atomistic simulations of radiation cascades.
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