Physics and Society
Nonmonotonic percolation threshold in correlated networks and hypergraphs
L. D. Valdez and C. E. La Rocca
We study the effect of assortative and disassortative mixing on the robustness of networks under random node failures. For ordinary (dyadic) networks, by using the generating function technique and
stochastic simulations, we show that the relationship between the Pearson assortativity coefficient $r$ and the percolation threshold $p_c$ is not always monotonic. More specifically, in certain regions of the parameter space of our model, moderately disassortative networks can be more fragile than either strongly disassortative or uncorrelated networks. We observe this nonmonotonic behavior for trimodal networks as well as for networks with Poisson and power-law degree distributions. We then extend our analysis to hypergraphs with correlations between node hyperdegree and hyperedge cardinality. For this case, we find that positively correlated hypergraphs tend to be more fragile than negatively correlated ones. Additionally, as in the dyadic case, the relationship between $r$ and $p_c$ is nonmonotonic, and the most fragile configuration does not correspond to the most assortative hypergraph.
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Instrumentation and Detectors
Observation of light production by charged particles in WLS fibers
I. Alekseev, A. Chvirova, M. Danilov et al. (+14 more)
Wavelength shifting (WLS) fibers are widely used in particle physics for light collection from scintillators. Light production by charged particles directly in WLS fibers is traditionally ignored. In this study, light produced by charged particles in WLS fibers is clearly observed. The light yield of different batches of Y11(200) 1 mm diameter WLS fibers expressed in the number of detected photo electrons is as large as $23\pm2~\%$ with respect to the light yield of the Bicron BCF-12 1 mm diameter scintillating fiber. This corresponds to about 1200
photons per MeV light production after taking into account different fiber light trapping efficiencies and emission spectra. In clear fibers of the same diameter, no scintillation light is produced, while Cherenkov light is clearly seen at the 45-degree crossing angle. The observed amount of light produced by charged particles in the WLS fibers is not small and should be taken into account in advanced detector simulations.
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All authors I. Alekseev, A. Chvirova, M. Danilov, S. Fedotov, A. Khotjantsev, M. Kolupanova, N. Kozlenko, A. Krapiva, Y. Kudenko, A. Mefodiev, O. Mineev, D. Novinsky, V. Rusinov, E. Samigullin, N. Skrobova, D. Svirida, E. Tarkovsky
Physics and Society · Cross-listed from cs.DL
Demanding peer review is associated with higher impact in published science
Huihuang Jiang, Heyang Li, Zifan Wang et al. (+2 more)
Peer review shapes which scientific claims enter the published record, but its internal dynamics are hard to measure at scale because reviewer criticism and author revision are usually embedded in long, unstructured correspondence. Here we use a fixed-
prompt large
language model pipeline to convert the review correspondence of Nature Communications papers published from 2017 to 2024 into structured reviewer–author interactions. We find that review pressure is concentrated in the first round and focused disproportionately on core claims rather than peripheral presentation. Higher average opinion strength is also associated with more reviewer disagreement, while review patterns vary little with broad team attributes, consistent with relatively impartial evaluation. Contrary to the intuition that stronger papers should pass review more smoothly, with greater reviewer–author agreement and less extensive revision, we find that stronger criticism, higher-quality comments, and greater revision burden are associated with higher later citation impact within accepted papers. We finally show that fields differ more in review style than in review length, pointing to disciplinary variation in how criticism is negotiated and resolved. These findings position open peer review not just as a gatekeeping mechanism but as a measurable record of how influential scientific claims are challenged, defended, and revised before entering the published record.
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All authors Huihuang Jiang, Heyang Li, Zifan Wang, Ying Fan, An Zeng
Atomic Physics
Parity-mixing interference in laser-assisted photoionization
N. Ouahioune, D. Hoff, P.K. Maroju et al. (+5 more)
Photoionization of atoms by high-order harmonics in the presence of a
laser may lead to
quantum interference from which information about the photoionization dynamics or the light fields can be extracted. Traditionally, this interference arises from two-
photon transitions involving the absorption of consecutive harmonics combined with the absorption and stimulated emission of a
laser photon. In this process, parity is conserved. Here, we investigate interference between one- and two-
photon transitions in helium using high-order harmonics generated by a few-cycle
laser and three-dimensional electron detection. In this case, parity is not conserved. We identify four parity-mixing interference pathways, involving two different harmonic fields or a single harmonic, together with absorption or emission of a probe
photon.
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All authors N. Ouahioune, D. Hoff, P.K. Maroju, C.L. Arnold, D. Busto, A. L'Huillier, M. Gisselbrecht, S. Carlström
Atmospheric and Oceanic Physics
The impact of two-dimensional filtering on SWOT observations with white noise
Ryan Shìjié Dù, Momme Hell, Luc Lenain et al. (+2 more)
The Surface Water and Ocean Topography (SWOT) mission provides two-dimensional observations of sea surface height (SSH) at unprecedented spatial resolution, enabling exploration of ocean variability down to scales of $O(10~\mathrm{ km})$. At these scales, however, interpreting SSH variability is challenging because ocean dynamical signals overlap with measurement noise, and their respective spectral signatures are not yet fully understood. Recent analyses of SWOT 2-km posting observations have shown that along-track spectra transition to flatter but still red spectra at scales around 30 km. These flatter portions of the spectra have a power-law-like behavior and spectral slopes of approximately $-1$ or steeper, and their magnitudes and slopes are correlated with SWOT measurement noise magnitude. Here, we investigate the hypothesis that these flatter but still red along-track small-scale spectra can arise from two-dimensional filtering and aliasing of spatially uncorrelated (white) noise. Using synthetic experiments, we show that the resulting one-dimensional along-track spectra exhibit a similar transition to red, power-law-like behavior at scales of 15–50 km, qualitatively similar to spectral behavior reported in SWOT observations. The transition scale and apparent spectral slopes depend on the noise level, its cross-track variability, and the background ocean signal. This finding highlights the importance of carefully accounting for measurement noise and processing effects when interpreting SWOT spectra, and suggests that a white noise model should serve as a baseline null hypothesis for small-scale spectral analyses.
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All authors Ryan Shìjié Dù, Momme Hell, Luc Lenain, Fabrice Ardhuin, A. B. Villas Bôas
Optics
Mirror Surface Evaluation for the Einstein Telescope Using Virtual Mirror Maps
A. Bianchi, A. C. Green, J. Degallaix et al. (+3 more)
The performance of mirrors in optical interferometers is critically influenced by their surface quality. Accurate metrology enables mirror surfaces to be characterized through phase maps describing their three-dimensional structure after coating. In this work, we combine Zernike
polynomial decomposition and spatial frequency (PSD) analysis with numerical optical simulations to quantify the impact of surface distortions on the reflected optical field. The method is validated using metrology data from mirrors currently installed in the Advanced Virgo gravitational-wave detector. Building on this validation, we introduce a framework for generating realistic virtual mirror maps that reproduce both low order aberrations and high spatial frequency content of measured surfaces. These virtual maps are used in optical simulations to systematically explore and compare candidate surface quality specifications for future detectors, with particular focus on the Einstein
Telescope. Our results show that metrology-informed virtual mirrors provide a practical design tool to assess the impact of different surface specifications on optical performance, and to relate future requirements to the performance of existing interferometers.
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All authors A. Bianchi, A. C. Green, J. Degallaix, F. A. Feldmann, A.Soflau, A. Freise
Fluid Dynamics
Flow Characterization of the Delft Multiphase Flow Tunnel
Lina Nikolaidou, Angeliki Laskari, Tom van Terwisga et al. (+1 more)
At the end of 2020, a new cavitation tunnel was commissioned at the Ship Hydrodynamics laboratory of TU Delft, replacing its 1960s predecessor. Since this was a new facility, a flow characterization campaign was performed to investigate the flow quality in the test section. To that end, velocity measurements were performed in the test section using
Laser Doppler Anemometry. Velocities in the range of 2.13 m/s to 9 m/s were measured and a linear relation was found between the freestream velocity and the rotational frequency of the thruster. Long term measurements at the center of the test section, did not reveal any large scale fluctuations of the mean velocity. The freestream
turbulence intensity was found to lie between 0.5% - 0.6% throughout the test section, after removing the measurement noise. Local measurements in various planes in the test section confirmed that the flow is uniform ($u_{local}< U_{\infty} \times 1\%$), with few outliers near the side walls, due to the turbulent boundary layer. Finally, preliminary measurements of the turbulent boundary layer (TBL) indicated that the TBL originates upstream of the test section and its growth is not strictly canonical. Smaller TBL thickness was found in the side wall compared to the top wall.
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All authors Lina Nikolaidou, Angeliki Laskari, Tom van Terwisga, Christian Poelma
Optics
Redefining the limits of real-time noise cancellation in optical fiber links
Charles A. McLemore, Marco Pomponio, Takuma Nakamura et al. (+4 more)
A broad and growing array of applications rely on the faithful transmission of ultrastable optical signals over noisy paths, requiring cancellation of environmentally induced noise. A generally accepted limit constrains how well the path length noise can be suppressed in real time. Here, we show that this standard limit is not fundamental and can be improved upon. By considering the temporal correlations between the round-trip and one-way signals, we develop a new framework for optimizing the noise cancellation feedback signal for any spatial distribution of noise along the signal path. We use this framework to surpass the standard limit in two sets of experiments. First, we demonstrate noise cancellation in a deployed urban optical fiber, where we achieve noise suppression approximately 6 dB beyond the standard limit. Then, in a reconfigurable lab-based fiber-optic testbed, we show that, for certain spatial distributions of noise, suppression of well over 10 dB beyond the standard limit is readily achievable. With the use of digital signal processing to generate the correction signal, our new technique requires no new electro-optic hardware relative to the field-standard noise cancellation scheme. This will allow for widespread adoption of these improved limits in existing systems, with applications in optical clock distribution, optical clock comparisons for fundamental physics and geodesy, and
quantum networking.
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All authors Charles A. McLemore, Marco Pomponio, Takuma Nakamura, Yifan Liu, Nazanin Hoghooghi, Antonio Mecozzi, Franklyn Quinlan
Biological Physics · Cross-listed from q-bio.PE
A generative model for bipartite gene-sharing networks
Jaime Iranzo, Pedro Jódar, Eugene V. Koonin et al. (+2 more)
Gene-sharing networks provide a powerful framework to study the
evolution of viruses and mobile genetic elements. These bipartite networks, which link genes to the genomes that contain them, exhibit characteristic degree distributions: a scale-free distribution for genes and an exponential-like decay for genomes. Here, we propose a mechanistic model that explains these patterns through fundamental evolutionary processes including horizontal gene transfer, capture of new genes, emergence of new genomes, and gene loss. Using a mean-field approximation, we derive analytical expressions for the asymptotic gene and genome degree distributions, recapitulating a power-law distribution for genes and an exponential distribution for genomes. Numerical simulations validate these predictions and yield parameter values that closely fit empirical data from dsDNA viruses, RNA viruses, and prokaryotic pangenomes. This simple model with only two parameters provides a generative framework for bipartite gene-sharing networks, offering qualitative and quantitative insights into the main evolutionary forces driving genome plasticity. Setting the gene loss rate to zero, the gene and genome degree distributions of the model closely fit the empirically observed distributions. Thus,
evolution of viruses appears to be dominated by gene gain, in agreement with the results of independent reconstructions of viral
evolution.
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All authors Jaime Iranzo, Pedro Jódar, Eugene V. Koonin, Susanna Manrubia, José A. Cuesta
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Symmetry-protected coexistence of a nodal surface and multiple types of Weyl fermions in $P6_3$-$\text{B}_{30}$
Xiao-Jing Gao, Yanfeng Ge and Yan Gao
The coexistence of topological states with different dimensionalities in a single crystalline system offers a unique platform to study the interplay of distinct fermionic excitations. Here, integrating first-principles calculations with
symmetry analysis, we propose the three-dimensional boron allotrope $P6_3$-$\text{B}_{30}$ as an ideal, structurally stable candidate for exploring multidimensional topological physics. Benefiting from the practically negligible
spin-orbit coupling of the light-element framework, $P6_3$-$\text{B}_{30}$ operates as a pristine spinless topological semimetal. We show that the combined time-reversal and twofold screw
symmetry ($\mathcal{T}S_{2z}$) enforces a robust two-dimensional nodal surface on the $k_z = \pi$ plane via a Kramers-like degeneracy. Concurrently, the system hosts a diverse set of zero-dimensional Weyl
fermions – including an unconventional double-Weyl point ($\mathcal{C} = -2$), conventional Type-I WPs ($\mathcal{C} = -1$), and completely tilted Type-II WPs ($\mathcal{C} = +1$) – emerging at the high-
symmetry points $\Gamma$ and K, as well as along the H-K path, protected by $C_6$ and $C_3$ crystalline rotational
symmetries. Crucially, the substantial momentum-space separation between the nodal surface and Weyl points allows for their unambiguous independent resolution. Calculations of the (100) surface states reveal distinct, nontrivial
Fermi arcs connecting Weyl nodes of opposite chirality. This work establishes $P6_3$-$\text{B}_{30}$ as a compelling material platform for investigating the physics of multidimensional hybrid topological
fermions and their interplay.
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Optics
Three-dimensional photon transport in spinodal photocatalytic aerogels: how bicontinuous morphology controls kinetic rate constants
Renaud A.L. Vallée
Anatase TiO2 dispersed in a silica aerogel
matrix forms porous monolithic photocatalysts promising for indoor air purification and VOC photo-degradation. Their bicontinuous spinodal architecture provides high surface area, structural integrity, and intense UV multiple scattering. Extracting kinetic descriptors from apparent rate constants requires an optical model for the
photon fluence, and current practice replaces the 3D pore network by a homogeneous 1D slab with effective optical coefficients – an approximation never quantified for spinodal geometries. We combine realistic 3D spinodal pore masks from Cahn-Hilliard spectral integration with 3D GPU-accelerated Monte Carlo (MC)
photon-migration simulations, introducing the solid-phase-weighted
estimator $\Phi_{3D}$ and comparing it with the conventional volume average $\Phi_{1D}$ and the
diffusion-approximation (DA) prediction $\Phi_{DA}$. The ratio $\Phi_{3D}/\Phi_{1D}$ equals 1.515 at porosity $\phi=0.70$ and 1.774 at $\phi=0.90$: the solid phase is preferentially illuminated, traced to optical phase contrast. Since pores neither absorb nor scatter,
photons cross quasi-ballistically, and the void phase sustains only $r=0.514$ of the solid-phase fluence, diluting the volume average with dark voxels. This ratio is porosity-independent, so the concentration ratio obeys the exact relation $1/[\phi r+(1-\phi)]$, reproducing both simulated values. The kinetic descriptor $k_{surf}\cdot K_{ads}$ is underestimated by 20% via the DA route and overestimated by 51.5% via the volume-averaged route. Homogeneous-slab MC simulations at matched optical thickness show that 84% of the fluence-weighted RMS discrepancy between MC and DA is intrinsic to the bicontinuous architecture and beyond any effective-medium DA. These results give a quantitative correction for kinetic extraction and design rules linking porosity, pore size and
photon utilisation.
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Optics
High-power-handling ultra-compact acousto-optic modulators using one-dimensional topological interface states on thin-film lithium tantalate
Yuqi Chen, Wenfeng Zhou, Min Sun et al. (+6 more)
Recent advances in integrated photonics have enabled on-chip signal modulation and processing through localized
photon-
phonon interactions. For acousto-optic devices, compact footprint and high efficiency are essential for dense integration, while strong power handling is critical for stable operation in demanding applications. However, it remains challenging to achieve these features simultaneously on existing integrated platforms. Here, we propose and experimentally demonstrate, for the first time on a thin-film lithium tantalate platform, an ultra-compact acousto-optic modulator based on topological interface states. Benefiting from the strong optical confinement of the topological boundary state, the device achieves a footprint of 0.13 by 0.12 mm2 and a half-wave voltage-length product of 0.491 Vcm. We further demonstrate stable acousto-optic modulation at an on-chip optical power of up to 28 dBm (630.9 mW), highlighting the strong power-handling capability of the thin-film lithium tantalate topological structure. This work provides a compact and high-power solution for microwave-to-photonic transduction and shows the potential of the thin-film lithium tantalate for robust integrated photonic systems.
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All authors Yuqi Chen, Wenfeng Zhou, Min Sun, Xun Zhang, Xin Wang, Qingqing Han, Minni Qu, Yikai Su, Yong Zhang
Atomic Physics · Cross-listed from quant-ph
Quantum information spreading in inhomogeneous spin ensembles
Rahul Gupta, Florian Mintert and Himadri Shekhar Dhar
We present a Krylov space based theoretical framework for modeling inhomogeneous
spin ensembles with arbitrary distributions of
spin frequencies and couplings. The framework is then used to asymptotically large
spin ensemble. In the single-excitation subspace, the Krylov construction allows for to derive exact expressions for the Lieb-Robinson velocity and
quantum speed limit, and figure of merit such as Krylov complexity. Our work reveals a strong dependence of the speed of information flow on the statistical distribution of resonance frequencies in the
spin ensemble with immediate implications for the design of components for
quantum technologies, realized for example with nitrogen vacancy centers,
nuclear spins or ultracold atoms.
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Fluid Dynamics
Nested Fourier-enhanced neural operator for efficient modeling of radiation transfer in fires
Anran Jiao, Wengyao Jiang, Xiaoyi Lu et al. (+2 more)
Computational fluid dynamics (CFD) has become an essential tool for predicting fire behavior, yet maintaining both efficiency and accuracy remains challenging. A major source of computational cost in fire simulations is the modeling of radiation transfer, which is usually the dominant heat transfer mechanism in fires. Solving the high-dimensional radiative transfer equation (RTE) with traditional numerical methods can be a performance bottleneck. Here, we present a machine learning framework based on
Fourier-enhanced multiple-input neural operators (
Fourier-MIONet) as an efficient alternative to direct numerical integration of the RTE. We first investigate the performance of neural operator architectures for a small-scale 2D pool fire and find that
Fourier-MIONet provides the most accurate radiative solution predictions. The approach is then extended to 3D CFD fire simulations, where the computational mesh is locally refined across multiple levels. In these high-resolution settings, monolithic surrogate models for direct field-to-field mapping become difficult to train and computationally inefficient. To address this issue, a nested
Fourier-MIONet is proposed to predict radiation solutions across multiple mesh-refinement levels. We validate the approach on 3D McCaffrey pool fires simulated with FireFOAM, including fixed fire sizes and a unified model trained over a continuous range of heat release rates (HRRs). The proposed method achieves global relative errors of 2-4% for 3D varying-HRR scenarios while providing faster inference than the estimated cost of one finite-volume radiation solve in FireFOAM for the 16-solid-angle case. With fast and accurate inference, the surrogate makes higher-fidelity radiation treatments practical and enables the incorporation of more spectrally resolved radiation models into CFD fire simulations for engineering applications.
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All authors Anran Jiao, Wengyao Jiang, Xiaoyi Lu, Yi Wang, Lu Lu
Optics
Twistoptics in Planar Heterostructures with an Arbitrary Number of Rotated 3D Thin Layers and 2D Conductive Sheets
Christian Lanza, José Álvarez-Cuervo, Kirill V. Voronin et al. (+5 more)
Twistoptics has recently emerged as a branch of nano-optics that explores light propagation in stacks of thin anisotropic layers rotated relative to one another. The concept is particularly relevant for polaritons – hybrid light-matter quasiparticles – in van der Waals (vdW) materials, where strong in-plane anisotropy and deep subwavelength confinement make the polaritonic dispersion highly sensitive to interlayer twist angles. This sensitivity enables exotic phenomena such as canalization, i.e., diffraction-free propagation, with potential applications ranging from thermal management to super-resolution imaging. Despite rapid progress, a general analytical framework to describe polariton propagation in twisted planar
heterostructures has been missing. Here we present an analytical model for planar stacks comprising an arbitrary number of finite-thickness anisotropic (biaxial) layers and infinitesimally thin anisotropic conductive sheets. The formalism and its high-momentum and thin-film approximations predict key polaritonic observables, such as wavelength, propagation length, and electromagnetic field distributions. We also provide open-access numerical scripts implementing the model to support their practical use. Together, these results provide a general theoretical foundation for twistoptics and should facilitate the discovery and accelerate the implementation of twist-engineered polaritonic phenomena across the electromagnetic spectrum.
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All authors Christian Lanza, José Álvarez-Cuervo, Kirill V. Voronin, Gonzalo Álvarez-Pérez, Aitana Tarazaga Martín-Luengo, Javier Martín-Sánchez, Alexey Y. Nikitin, Pablo Alonso-González
Atomic Physics · Cross-listed from quant-ph
Optimally Controlled Storage of a Qubit in an Inhomogeneous Spin Ensemble
Rahul Gupta, Florian Mintert and Himadri Shekhar Dhar
The storage of
quantum information in
spin-ensembles is limited by practically unavoidable inhomogeneous broadening, and the macroscopic number of
spins in such an ensemble makes the design of control solutions to increase the coherence time a challenging task. Together with a concurrently developed Krylov theory that allows us to treat the control problem efficiently, we design optimal cavity modulation for such
spin ensembles that achieve an order of magnitude enhancement in
qubit lifetime compared to the losses due to inhomogeneity and cavity decay.
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Optics
Contrasting ultrafast light-driven electron-hole interaction dynamics in monolayer MoS$_2$ and metallic NbSe$_2$
Aday Cárdenas, Rui E.F. Silva and Álvaro Jiménez-Galán
We study strong-field driven ultrafast dynamics and high-harmonic generation (HHG) in monolayer 2H-NbSe$_2$ and compare them with those of monolayer 2H-MoS$_2$ by solving the multiband reduced-density-
matrix equations including time-dependent electron-electron interaction effects within the time-dependent Hartree + screened exchange (TD-HSEX). In MoS$_2$, these interactions strongly enhance the harmonic yield and modify the harmonic phases and angular emission patterns, wheras in NbSe$_2$ the yield enhancement is weaker but clear phase and angular changes remain. We trace these differences to the distinct optical resonances and to the different bands involved in the emission in each material. Finally, we show that carrier injection into empty bands of NbSe$_2$ differs qualitatively from interband excitation in MoS$_2$, and is well captured at a qualitative level by a Keldysh tunneling rate with a time-dependent band separation, allowing to control the timing and the region of injection of carriers to empty bands of the metal with the field parameters. Our work provides a framework to interpret ultrafast electron-hole interaction effects in experimental high harmonic generation spectra across semiconducting and metallic systems.
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Atomic Physics · Cross-listed from quant-ph
Dynamic rephasing in a telecom warm vapor quantum memory
Ilse Maillette de Buy Wenniger, Paul Burdekin, Shicheng Zhang et al. (+6 more)
The Off-Resonant Cascaded Absorption (ORCA) protocol in warm atomic vapors offers a scalable platform for high-bandwidth, low noise
quantum memories, but its coherence time is fundamentally limited by Doppler-induced dephasing. We introduce and experimentally demonstrate a dynamic rephasing protocol that counteracts Doppler dephasing in a telecom-band ORCA
quantum memory. By transferring the stored excitation to an auxiliary shelving state, we effectively reverse the accumulated Doppler phase and extend the storage time by a factor of 50 while preserving the
memory's GHz bandwidth and low noise. Using this protocol, we then demonstrate on-demand storage and
retrieval of four independent time-bin modes within a single warm vapor
memory – showing that Doppler dephasing can alternatively be harnessed for high-dimensional temporal mode processing. Our results establish rephasing in warm atomic vapors as a viable route toward high-bandwidth, temporally multiplexed
quantum memories operating at room temperature.
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All authors Ilse Maillette de Buy Wenniger, Paul Burdekin, Shicheng Zhang, Mikhael J. Rasiah, Anindya Rastogi, Otto T. P. Schmidt, Patrick M. Ledingham, Ian A. Walmsley, S. E. Thomas
Computational Physics · Cross-listed from cs.LG
MolCryst-MLIPs: A Machine-Learned Interatomic Potentials Database for Molecular Crystals
Adam Lahouari, Shen Ai, Jihye Han et al. (+16 more)
We present an open Molecular
Crystal (MC) database of Machine-Learned Interatomic Potentials (MLIP) called MolCryst-MLIPs. The first release comprises fine-tuned MACE models for nine molecular
crystal systems—Benzamide, Benzoic acid, Coumarin, Durene, Isonicotinamide, Nicotinic acid , Niacinamide, Pyrazinamide, and Resorcinol—developed using the Automated Machine Learning Pipeline (AMLP), which streamlines the entire MLIP development workflow, from reference data generation to model training and validation, into a reproducible and user-friendly pipeline. Models are fine-tuned from the MACE-MH-1 foundation model omol head), yielding a mean energy MAE of 0.141 kJ/mol/atom and a mean force MAE of 0.648 kJ/mol/Angstrom across all systems. Benchmarked against three state-of-the-art foundation models on the DFT-labelled polymorph set, only the fine-tuned models resolve the polymorphic energy landscape. Dynamical stability and structural integrity, as assessed through energy conservation, P2 orientational order parameters, and radial distribution functions, are evaluated using molecular dynamics simulations. The released models and
datasets constitute a growing open database of validated MLIPs, ready for production MD simulations of molecular
crystal polymorphism across the polymorphic landscape of each target compound under different thermodynamic conditions.
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All authors Adam Lahouari, Shen Ai, Jihye Han, Jillian Hoffstadt, Philipp Hoellmer, Charlotte Infante, Pulkita Jain, Sangram Kadam, Maya M. Martirossyan, Amara McCune, Hypatia Newton, Shlok J. Paul, Willmor Pena, Jonathan Raghoonanan, Sumon Sahu, Oliver Tan, Andrea Vergara, Jutta Rogal, Mark E. Tuckerman
Applied Physics · Cross-listed from cond-mat.mes-hall
Giant Room-Temperature Third-Order Electrical Transport in a Thin-Film Altermagnet Candidate
Hongyu Chen, Peixin Qin, Ziang Meng et al. (+14 more)
Quantum geometry, a
quantum mechanical quantity comprised of Berry
curvature and
quantum metric, describes the
geometric structure of the electronic bands in solids. The correlation between nontrivial
quantum geometry and
quantum materials leads to new findings in condensed matter systems. Here we demonstrate that altermagnets, with spontaneously broken time-reversal (T)- half-
lattice-translation and parity-time
symmetry, host both T-odd and T-even
quantum geometric quantities that simultaneously manifest themselves despite the vanishing net magnetization. Consequently,
giant room-temperature third-order electrical transport responses with sizable
quantum geometric contributions are observed in (101)-oriented RuO2 thin films, an altermagnetic candidate; in particular, the third-order
Hall effect is intimately correlated with altermagnetic order and can serve as a promising tool for detecting the Neel vector. Our work not only supports the existence of altermagnetism in 8-nm-thick RuO2 thin films, but also shows altermagnets as a versatile platform for exploring
quantum geometry and constructing
quantum electronic and spintronic devices.
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All authors Hongyu Chen, Peixin Qin, Ziang Meng, Guojian Zhao, Kai Chen, Chuanying Xi, Xiaoning Wang, Li Liu, Zhiyuan Duan, Sixu Jiang, Jingyu Li, Xiaoyang Tan, Jinghua Liu, Jianfeng Wang, Huiying Liu, Chengbao Jiang, Zhiqi Liu
Optics
Time-resolved SNOM via phase-domain sampling
Philipp Schwendke, Julia Stähler and Samuel Palato
Time-resolved scanning near-field optical microscopy (tr-SNOM) enables the measurement of the dynamic optical response of functional surfaces beyond the diffraction limit. Experimental challenges are imposed both by the use of a pulsed light source, and by the need for interferometric signal modulation to isolate the near-field contribution. We present a novel experimental approach to retrieve the tr-SNOM signal using a 200 kHz
laser system and pseudo-heterodyne modulation. We circumvent the Nyquist limit for spectral demodulation by sampling modulation phases, pump intensity and SNOM signal for every
laser shot. A general time-resolved SNOM signal is derived, independent of detection scheme or physical assumptions about the near-field enhancement, and is successfully measured and isolated on WS$_2$ monolayer and multilayer regions. We confirm localization by signal-distance curves, spatial confinement at material boundaries, and by identifying signal contributions at individual modulation harmonics. Disentangling the dynamic contributions enables us to extract the dynamic dielectric function of the sample. Showing the capability of phase-domain sampling paves the way to integration of more diverse and specialized light sources, growing the potential of optical ultrafast near-field measurements.
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Physics and Society
Sandpile Economics: Theory, Identification, and Evidence
Diego Vallarino
Why do capitalist economies recurrently generate crises whose severity is disproportionate to the size of the triggering shock? This paper proposes a structural answer grounded in the evolutionary geometry of production networks. As economies evolve through specialization, integration, and competitive selection, their inter-sectoral linkages drift toward configurations of increasing
geometric fragility, eventually crossing a threshold beyond which small disturbances generate disproportionately large cascades. We introduce Sandpile Economics, a formal framework that interprets macroeconomic instability as an emergent property of disequilibrium production networks. The key state variable is the Forman–
Ricci curvature of the input–output graph, capturing local substitution possibilities when supply chains are disrupted. We show that when
curvature falls below an endogenous threshold, the distribution of cascade sizes follows a power law with tail index $\alpha \in (1,2)$, implying a regime of unbounded amplification. The underlying mechanism is evolutionary: specialization reduces input substitutability, pushing the economy toward criticality, while crisis episodes induce endogenous network reconfiguration and path dependence. These dynamics are inherently non-ergodic and cannot be captured by representative-
agent frameworks. Empirically, using global input–output data, we document that production networks operate in persistently negative
curvature regimes and that
curvature robustly predicts medium-run output dynamics. A one-standard-deviation increase in
curvature is associated with higher cumulative growth over three-year horizons, and
curvature systematically outperforms standard network metrics in explaining cross-country differences in resilience.
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Physics and Society · Cross-listed from cond-mat.stat-mech
Role of volatility mixing in wealth condensation transition
Jaeseok Hur, Meesoon Ha and Hawoong Jeong
We study the role of heterogeneous
volatility in a networked wealth dynamics model and its impact on the wealth condensation transition. Extending the Bouchaud-Mézard framework, we introduce binary
volatility in networks and investigate how its configuration affects the effective power-law tail exponent of the wealth distribution. Using a
stochastic block model, we control the mixing between
volatility groups and show that the effective exponent is governed not only by the global parameter $\Lambda=2J/\beta^2$ but also by the
volatility configuration in the network. We find that local interactions between nodes with different
volatility induce the neutralization of group-wise exponents, which lowers the aggregate tail exponent and yields a condensation transition across $\gamma_{\rm c}=2$. Our results identify
volatility mixing as another control mechanism for wealth condensation and highlight the importance of noise heterogeneity in nonequilibrium systems on networks.
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Atomic Physics · Cross-listed from quant-ph
Experimental realisation of topological spin textures in a Penning trap
Julian Y. Z. Jee, Nihar Makadia, Joseph H. Pham et al. (+4 more)
Quantum simulation with controllable many-body platforms offers a powerful route to exploring complex phases and dynamics that are difficult to access in natural materials. Among these, topological
spin textures such as skyrmions are central to modern condensed-matter physics and play a key role in
chiral quantum many-body systems. Their controlled realisation in large, programmable
quantum platforms, however, remains an outstanding challenge. Here, we report deterministic generation and site-resolved reconstruction of topological
spin textures in a two-dimensional
crystal of more than 150 trapped ions. Using globally applied
spin-dependent forces, we generate skyrmion configurations and reconstruct the full vector
spin field with single-ion resolution, obtaining a winding number of 0.99$\pm$0.02 and a mean local fidelity of 0.87$\pm$0.04. In addition, we implement single-ion-resolved control to deterministically prepare domain-wall states, extending our approach to a broader class of non-uniform
spin textures. These results establish trapped-ion
crystals as a platform for engineering complex
spin textures and open the door to exploring
topology-dependent nonequilibrium dynamics in long-range interacting
quantum systems.
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All authors Julian Y. Z. Jee, Nihar Makadia, Joseph H. Pham, Gustavo Café de Miranda, Michael J. Biercuk, Athreya Shankar, Robert N. Wolf
Optics
Breakdown of spallation in multi-pulse ultrafast laser ablation
David Redka, Julian Vollmann, Nicolas Thomae et al. (+2 more)
Ultrashort-pulse
laser ablation of metals near damage threshold is governed by homogeneous spallation, in which tensile unloading releases a nanometre-thin
liquid film whose optical signatures are temporally evolving concentric Newton rings in pump–probe experiments. This well-established picture rests almost exclusively on single-pulse results obtained on ideally flat surfaces, yet application-oriented processing invariably operates in a multi-pulse regime in which each pulse irradiates a surface progressively modified by preceding pulses. Whether homogeneous spallation persists under these conditions has remained an open question. Here we resolve this question using time-resolved pump-probe interferometry applied pulse by pulse to austenitic stainless steel. We show that homogeneous spallation dominates the first pulse, while its contribution is strongly reduced for the second pulse. By the third pulse, Newton rings vanish and sustained surface bulging collapses, with the optical transients fully saturating into a phase-explosion-like signature by the fourth pulse.
Fourier-domain coherence analysis rules out roughness-induced decoherence as an optical artefact. Four independent observables, spanning time-resolved and final-state measurements, converge on the same transition after three to four pulses. Spallation-layer formation, widely invoked to explain ultrashort-pulse ablation of metals, is thus a single-pulse phenomenon rather than a multi-pulse ablation mechanism.
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All authors David Redka, Julian Vollmann, Nicolas Thomae, Maximilian Spellauge, Heinz P. Huber
Computational Physics
NEPMaker: Active learning of neuroevolution machine learning potential for large cells
Junjie Wang, Shuning Pan, Haoting Zhang et al. (+4 more)
Machine learning potentials (MLPs) achieve near first-principles accuracy but often fail for atomic environments outside the training distribution. Active learning can mitigate this limitation; however, its application to large-scale simulations is hindered by the prohibitive cost of labeling entire configurations. Here, we develop a D-optimality-driven active learning framework for the neuroevolution potential (NEP) implemented within the GPUMD package, named NEPMaker. Extrapolative atomic environments are identified on-the-fly and embedded into locally periodic structures, where boundary atoms are optimized to remain close to the training distribution. This strategy enables large-scale simulations to directly contribute to
dataset construction, significantly reducing extrapolation errors while improving model robustness and transferability. The proposed framework provides a scalable route for constructing reliable machine learning potentials in complex materials systems, including those involving defects, interfaces, and phase transitions.
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All authors Junjie Wang, Shuning Pan, Haoting Zhang, Qiuhan Jia, Chi Ding, Zheyong Fan, Jian Sun
Biological Physics · Cross-listed from cond-mat.soft
Beads, springs and fields: particle-based vs continuum models in cell biophysics
Valerio Sorichetti, Juraj Májek, Ivan Palaia et al. (+4 more)
Quantitative modeling has become an essential tool in modern biophysics, driven by advances in both experimental techniques and theoretical frameworks. Powerful high-resolution techniques now provide detailed
datasets spanning molecular to tissue scales, allowing to visualize cellular structures with unprecedented detail. In parallel, developments in soft and active matter physics have established a robust theoretical basis for describing biological systems. In this context, two main modeling paradigms have emerged: particle-based models, which explicitly represent discrete components and their interactions, and continuum models, which describe systems through spatially varying fields. We compare these approaches across biological scales, highlighting their respective strengths, limitations, and domains of applicability. To keep our discussion biologically relevant, we focus on five systems of fundamental importance: the cytoskeleton, membranes, chromatin, biomolecular condensates and tissues. With this Review, we thus aim to provide a framework for both theorists and experimentalists to select appropriate modeling strategies, and highlight future directions in biophysical modeling.
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All authors Valerio Sorichetti, Juraj Májek, Ivan Palaia, Fernanda Pérez-Verdugo, Christian Vanhille-Campos, Edouard Hannezo, An{\dj}ela Šarić
Optics · Cross-listed from cond-mat.other
Phonon drag as a mechanism of delayed terahertz response of metals
Ivan Oladyshkin
We show that electron drag by nonequilibrium
phonons describes the actual waveform and spectrum of terahertz pulses generated during femtosecond
laser irradiation of metals. In contrast to previous models, there is a picosecond delay in the drag force development due to the relatively slow
lattice heating and finite
phonon lifetime. We also predict that, at high pump fluences, a macroscopic deformation wave enhances nonlinearly the drag force and terahertz response. Our results establish the terahertz pulse waveform as a direct probe of ultrafast
lattice dynamics in metals.
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Optics
Non-Hermitian reshaping of high-order Landau modes
Zhihao Wang, Jie Jiang, Yanji Zheng et al. (+6 more)
When charged particles are subjected to strong
magnetic fields, they form discrete energy levels known as Landau levels. The Landau levels consist of a series of degenerate states of Landau modes, making them a promising platform for large-capacity information processing. However, to date, exploiting the high-order Landau modes and control their spatial distributions has remained elusive. Here, we propose to construct
magnetic fields, electric fields, and imaginary momentum simultaneously to reshape high-order Landau modes in non-Hermitian systems. By building a non-Hermitian electric
circuit platform, we experimentally realize pseudomagnetic fields via inhomogeneous coupling and pseudoelectric fields via a gradient on-site potential, while simultaneously introducing an imaginary momentum via non-reciprocal coupling. We directly observe multi-frequency single-peak localization of high-order Landau modes. Our work provides a universal method for manipulating high-order Landau modes and exploring applications in nonHermitian systems, such as frequency multiplexing and wave packet reshaping.
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All authors Zhihao Wang, Jie Jiang, Yanji Zheng, Wen Zhao, Chenyang Wang, Zhiwei Guo, Yong-Chun Liu, Shuang Zhang, Cuicui Lu
Optics
Tuning light-matter interaction of near-infrared nanoplasmonic scintillators
Michał Makowski, Dominik Kowal and Muhammad Danang Birowosuto
Nanoplasmonic modification of scintillation has so far been explored mainly in the weak-coupling regime, where changes in the local density of optical states enhance radiative recombination via Purcell-type rate engineering. By contrast, strong light-matter coupling generates hybrid states that modify emission dynamics beyond simple decay-rate acceleration, but its implications for scintillator nanocrystals (NCs) under ionizing radiation remain poorly understood. All of these effects are beneficial for near-infrared scintillators, which are typically slow and have low brightness. Here, we present a
quantum-optical framework to investigate how near-infrared scintillator NCs coupled to nanoplasmonic
antennas evolve from weak coupling toward strong light-matter coupling. We compare broad- and narrow-
antenna platforms with single and periodic Au nanorods and
benchmark them against conductive plasmonic
antennas based on indium tin
oxide and
graphene. As representative emitters, we consider wide-band PbS NCs and narrow-band cubic Lu2O3:Er3+ scintillators. The calculations show that the onset of strong-coupling signatures is jointly governed by emitter dephasing and the
antenna linewidth, with narrow-band emitters coupled to spectrally narrow
antennas providing the most favorable conditions. Among the platforms considered,
graphene gives the lowest threshold (g = 4 meV) for observable coherent exchange owing to its ultranarrow
antenna linewidth (ąppa} = 3.5 meV). These results identify near-infrared conductive nanoantennas, particularly
graphene-based ones, as promising platforms for accessing hybrid scintillation regimes relevant to radiation detection.
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