id
stringlengths 64
64
| published
stringlengths 19
25
| title
stringlengths 7
262
| description
stringlengths 6
54.4k
| link
stringlengths 31
227
| category
stringclasses 6
values | image
stringlengths 3
247
|
|---|---|---|---|---|---|---|
0c0bc9a9b698d51b33f5719cde08aba9d842b97ef6a6f55f8cdb14dc9da7a786
|
2026-01-16T00:00:00-05:00
|
Calibrating Generative Models to Distributional Constraints
|
arXiv:2510.10020v2 Announce Type: replace-cross Abstract: Generative models frequently suffer miscalibration, wherein statistics of the sampling distribution such as class probabilities deviate from desired values. We frame calibration as a constrained optimization problem and seek the closest model in Kullback-Leibler divergence satisfying calibration constraints. To address the intractability of imposing these constraints exactly, we introduce two surrogate objectives for fine-tuning: (1) the relax loss, which replaces the constraint with a miscalibration penalty, and (2) the reward loss, which converts calibration into a reward fine-tuning problem. We demonstrate that these approaches substantially reduce calibration error across hundreds of simultaneous constraints and models with up to one billion parameters, spanning applications in protein design, image generation, and language modeling.
|
https://arxiv.org/abs/2510.10020
|
Academic Papers
|
svg
|
4e52cc08086c5f0e6f634a687b2c49361365b55640d81f8346e47356f6b9ca05
|
2026-01-16T00:00:00-05:00
|
Pulse Shaping Filter Design for Integrated Sensing & Communication with Zak-OTFS
|
arXiv:2510.15195v2 Announce Type: replace-cross Abstract: Zak-OTFS provides a framework for integrated sensing & communication (ISAC) in high delay and Doppler spread environments. Pulse shaping filter design enables joint optimization of sensing and communication performance. For sensing, a localized pulse shaping filter enables input-output (I/O) relation estimates close to the physical scattering channel. For communication, orthogonality of the pulse shape on the information lattice prevents inter-symbol interference, and no time and bandwidth expansion enables full spectral efficiency. A filter simultaneously meeting all three objectives is ideal for ISAC. Existing filter designs achieve two, but not all three objectives. In this work, we design pulse shaping filters meeting all three objectives via the Isotropic Orthogonal Transform Algorithm. The proposed filters have improved spectral efficiency, data detection and sensing performance over existing filter choices.
|
https://arxiv.org/abs/2510.15195
|
Academic Papers
|
svg
|
62a807a4789298af147e39b5bbfa7baebbda8e9c196b5c660eb9826ab1fb5a2f
|
2026-01-16T00:00:00-05:00
|
Cross-Modal Fine-Tuning of 3D Convolutional Foundation Models for ADHD Classification with Low-Rank Adaptation
|
arXiv:2511.06163v2 Announce Type: replace-cross Abstract: Early diagnosis of attention-deficit/hyperactivity disorder (ADHD) in children plays a crucial role in improving outcomes in education and mental health. Diagnosing ADHD using neuroimaging data, however, remains challenging due to heterogeneous presentations and overlapping symptoms with other conditions. To address this, we propose a novel parameter-efficient transfer learning approach that adapts a large-scale 3D convolutional foundation model, pre-trained on CT images, to an MRI-based ADHD classification task. Our method introduces Low-Rank Adaptation (LoRA) in 3D by factorizing 3D convolutional kernels into 2D low-rank updates, dramatically reducing trainable parameters while achieving superior performance. In a five-fold cross-validated evaluation on a public diffusion MRI database, our 3D LoRA fine-tuning strategy achieved state-of-the-art results, with one model variant reaching 71.9% accuracy and another attaining an AUC of 0.716. Both variants use only 1.64 million trainable parameters (over 113x fewer than a fully fine-tuned foundation model). Our results represent one of the first successful cross-modal (CT-to-MRI) adaptations of a foundation model in neuroimaging, establishing a new benchmark for ADHD classification while greatly improving efficiency.
|
https://arxiv.org/abs/2511.06163
|
Academic Papers
|
svg
|
cbb71fe4c5729dc29ba133295ac0d3a5ac8bfc82a4fec64b55747c273f3b3267
|
2026-01-16T00:00:00-05:00
|
The free bifibration on a functor
|
arXiv:2511.07314v3 Announce Type: replace-cross Abstract: We consider the problem of constructing the free bifibration generated by a functor of categories $p : D \to C$. This problem was previously considered by Lamarche, and is closely related to the problem, considered by Dawson, Par\'e, and Pronk, of ``freely adjoining adjoints'' to a category. We develop a proof-theoretic approach to the problem, beginning with a construction of the free bifibration $\Lambda_p : Bifib(p)\to C$ in which objects of $Bifib(p)$ are formulas of a primitive ``bifibrational logic'', and arrows are derivations in a cut-free sequent calculus modulo a notion of permutation equivalence. We show that instantiating the construction to the identity functor generates a _zigzag double category_ $\mathbb{Z}(C)$, which is also the free double category with companions and conjoints (or fibrant double category) on $C$. The approach adapts smoothly to the more general task of building $(P,N)$-fibrations, where one only asks for pushforwards along arrows in $P$ and pullbacks along arrows in $N$ for some subsets of arrows; this encompasses Kock and Joyal's notion of _ambifibration_ when $(P,N)$ form a factorization system. We establish a series of progressively stronger normal forms, guided by ideas of _focusing_ from proof theory, and obtain a canonicity result under assumption that the base category is factorization preordered relative to $P$ and $N$. This canonicity result allows us to decide the word problem and to enumerate relative homsets without duplicates. Finally, we describe several examples of a combinatorial nature, including a category of plane trees generated as a free bifibration over $\omega$, and a category of increasing forests generated as a free ambifibration over $\Delta$, which contains the lattices of noncrossing partitions as quotients of its fibers by the Beck-Chevalley condition for bicartesian squares.
|
https://arxiv.org/abs/2511.07314
|
Academic Papers
|
svg
|
0b8c3f62426ae1f63a41185bf7337004fa680ae106af73d8932eb77619838faa
|
2026-01-16T00:00:00-05:00
|
OBLR-PO: A Theoretical Framework for Stable Reinforcement Learning
|
arXiv:2511.23310v2 Announce Type: replace-cross Abstract: Existing reinforcement learning (RL)-based post-training methods for large language models have advanced rapidly, yet their design has largely been guided by heuristics rather than systematic theoretical principles. This gap limits our understanding of the properties of the gradient estimators and the associated optimization algorithms, thereby constraining opportunities to improve training stability and overall performance. In this work, we provide a unified theoretical framework that characterizes the statistical properties of commonly used policy-gradient estimators under mild assumptions. Our analysis establishes unbiasedness, derives exact variance expressions, and yields an optimization-loss upper bound that enables principled reasoning about learning dynamics. Building on these results, we prove convergence guarantees and derive an adaptive learning-rate schedule governed by the signal-to-noise ratio (SNR) of gradients. We further show that the variance-optimal baseline is a gradient-weighted estimator, offering a new principle for variance reduction and naturally enhancing stability beyond existing methods. These insights motivate Optimal Baseline and Learning-Rate Policy Optimization (OBLR-PO), an algorithm that jointly adapts learning rates and baselines in a theoretically grounded manner. Experiments on Qwen3-4B-Base and Qwen3-8B-Base demonstrate consistent gains over existing policy optimization methods, validating that our theoretical contributions translate into practical improvements in large-scale post-training.
|
https://arxiv.org/abs/2511.23310
|
Academic Papers
|
svg
|
31612467231689dbb3d0ac973ed5b3189be2c500d68ded9f3b64a5a6f246df74
|
2026-01-16T00:00:00-05:00
|
TPV: Parameter Perturbations Through the Lens of Test Prediction Variance
|
arXiv:2512.11089v2 Announce Type: replace-cross Abstract: We identify test prediction variance (TPV) -- the first-order sensitivity of model outputs to parameter perturbations around a trained solution -- as a unifying quantity that links several classical observations about generalization in deep networks. TPV is a fully label-free object whose trace form separates the geometry of the trained model from the specific perturbation mechanism, allowing a broad family of parameter perturbations like SGD noise, label noise, finite-precision noise, and other post-training perturbations to be analyzed under a single framework. Theoretically, we show that TPV estimated on the training set converges to its test-set value in the overparameterized limit, providing the first result that prediction variance under local parameter perturbations can be inferred from training inputs alone. Empirically, TPV exhibits a striking stability across datasets and architectures -- including extremely narrow networks -- and correlates well with clean test loss. Finally, we demonstrate that modeling pruning as a TPV perturbation yields a simple label-free importance measure that performs competitively with state-of-the-art pruning methods, illustrating the practical utility of TPV. Code available at github.com/devansharpit/TPV.
|
https://arxiv.org/abs/2512.11089
|
Academic Papers
|
svg
|
f136d7e5feb0d5116a3754810be9408d6cc8611fd49bfc052433ee19ef97a5fd
|
2026-01-16T00:00:00-05:00
|
Information Theoretic Optimal Surveillance for Epidemic Prevalence in Networks
|
arXiv:2601.04267v2 Announce Type: replace-cross Abstract: Estimating the true prevalence of an epidemic outbreak is a key public health problem. This is challenging because surveillance is usually resource intensive and biased. In the network setting, prior work on cost sensitive disease surveillance has focused on choosing a subset of individuals (or nodes) to minimize objectives such as probability of outbreak detection. Such methods do not give insights into the outbreak size distribution which, despite being complex and multi-modal, is very useful in public health planning. We introduce TESTPREV, a problem of choosing a subset of nodes which maximizes the mutual information with disease prevalence, which directly provides information about the outbreak size distribution. We show that, under the independent cascade (IC) model, solutions computed by all prior disease surveillance approaches are highly sub-optimal for TESTPREV in general. We also show that TESTPREV is hard to even approximate. While this mutual information objective is computationally challenging for general networks, we show that it can be computed efficiently for various network classes. We present a greedy strategy, called GREEDYMI, that uses estimates of mutual information from cascade simulations and thus can be applied on any network and disease model. We find that GREEDYMI does better than natural baselines in terms of maximizing the mutual information as well as reducing the expected variance in outbreak size, under the IC model.
|
https://arxiv.org/abs/2601.04267
|
Academic Papers
|
svg
|
bd04c53f835d440c6b43e2a49323ed9cce030eef2882c58801a38dfbc3643974
|
2026-01-16T00:00:00-05:00
|
Wasserstein-p Central Limit Theorem Rates: From Local Dependence to Markov Chains
|
arXiv:2601.08184v2 Announce Type: replace-cross Abstract: Finite-time central limit theorem (CLT) rates play a central role in modern machine learning. In this paper, we study CLT rates for multivariate dependent data in Wasserstein-$p$ ($W_p$) distance, for general $p \geq 1$. We focus on two fundamental dependence structures that commonly arise in machine learning: locally dependent sequences and geometrically ergodic Markov chains. In both settings, we establish the first optimal $O(n^{-1/2})$ rate in $W_1$, as well as the first $W_p$ ($p\ge 2$) CLT rates under mild moment assumptions, substantially improving the best previously known bounds in these dependent-data regimes. As an application of our optimal $W_1$ rate for locally dependent sequences, we further obtain the first optimal $W_1$-CLT rate for multivariate $U$-statistics. On the technical side, we derive a tractable auxiliary bound for $W_1$ Gaussian approximation errors that is well suited for studying dependent data. For Markov chains, we further prove that the regeneration time of the split chain associated with a geometrically ergodic chain has a geometric tail without assuming strong aperiodicity or other restrictive conditions. These tools may be of independent interests and enable our optimal $W_1$ rates and underpin our $W_p$ ($p\ge 2$) results.
|
https://arxiv.org/abs/2601.08184
|
Academic Papers
|
svg
|
21e0e2b6babb1ff7a7cb977e7d8dac0ba446b04111f0f5a4020112b9c6da283a
|
2026-01-16T00:00:00-05:00
|
Sample Complexity of Composite Quantum Hypothesis Testing
|
arXiv:2601.08588v2 Announce Type: replace-cross Abstract: This paper investigates symmetric composite binary quantum hypothesis testing (QHT), where the goal is to determine which of two uncertainty sets contains an unknown quantum state. While asymptotic error exponents for this problem are well-studied, the finite-sample regime remains poorly understood. We bridge this gap by characterizing the sample complexity -- the minimum number of state copies required to achieve a target error level. Specifically, we derive lower bounds that generalize the sample complexity of simple QHT and introduce new upper bounds for various uncertainty sets, including of both finite and infinite cardinalities. Notably, our upper and lower bounds match up to universal constants, providing a tight characterization of the sample complexity. Finally, we extend our analysis to the differentially private setting, establishing the sample complexity for privacy-preserving composite QHT.
|
https://arxiv.org/abs/2601.08588
|
Academic Papers
|
svg
|
3b272991e91bd8db29a08db3500361472bcd9880c430de566ec496ec15c0618b
|
2026-01-16T00:00:00-05:00
|
Dedifferentiation stabilizes stem cell lineages: From CTMC to diffusion theory and thresholds
|
arXiv:2601.09752v1 Announce Type: new Abstract: We study stem-terminally differentiated (TD) lineages in small niches where demographic noise from discrete division and death events is non-negligible. Starting from a mechanistic five-channel, density-dependent CTMC (symmetric self-renewal, symmetric differentiation, asymmetric division, dedifferentiation, TD death), we derive its mean-field limit and a functional CLT, obtaining a chemical Langevin diffusion whose explicit state-dependent covariance exactly matches the CTMC's aggregated channel-wise infinitesimal covariances. Within this diffusion approximation we remove the dedifferentiation flux and obtain a sharp dichotomy: in subcritical regimes the stem coordinate becomes extinct asymptotically almost surely, whereas in supercritical regimes polynomial moments diverge exponentially. This identifies, at the diffusion level, a structural failure mode of strictly hierarchical lineages under demographic fluctuations and clarifies how a cyclic return flux can rescue homeostasis. For interpretation we also derive an exact totals ODE backbone from a damage-structured transport model and obtain two steady-state constraints (ratio and equalization laws) linking compartment ratios to turnover and balancing dedifferentiation against fate bias. Numerical experiments corroborate the $\Omega^{-1/2}$ fluctuation scaling, illustrate the pathology, and contrast theorem-regime global convergence with threshold (Allee-type) behaviour outside the theorem hypotheses.
|
https://arxiv.org/abs/2601.09752
|
Academic Papers
|
svg
|
55621c494e57b64f2c368834ecac28d1398e495bd78c1547b9a3448bc176731e
|
2026-01-16T00:00:00-05:00
|
Viewpoint: On the Emergence of van der Waals Magnets: A Personal Reflection
|
arXiv:2601.09759v1 Announce Type: new Abstract: The observation of magnetism in atomically thin van der Waals (vdW) antiferromagnets (FePS$_3$, NiPS$_3$, and MnPS$_3$) in 2016 marked an important moment in the development of two-dimensional (2D) physics. In this personal reflection, I describe how a simple question, posed in the early 2010s, motivated experimental efforts that culminated in the demonstration of antiferromagnetic order in monolayer FePS$_3$. Alongside subsequent reports of vdW ferromagnets in 2017, these developments helped establish intrinsic magnetism as a viable degree of freedom in atomically thin materials. I close with personal lessons drawn from this period and a perspective on the opportunities that now shape the field's second decade and beyond.
|
https://arxiv.org/abs/2601.09759
|
Academic Papers
|
svg
|
f1b1b736f381db0c70eb8cee6a56224efb62adc5305e76ee180f1279fe8ee1e7
|
2026-01-16T00:00:00-05:00
|
Remarks on Galilean electromagnetism
|
arXiv:2601.09761v1 Announce Type: new Abstract: It is shown that equations describing the Galilean electromagnetism in the presence of sources hold invariant under the l-conformal Galilei group for an arbitrary (half)integer parameter l. The group contains transformations which link an inertial frame of reference to those moving with constant accelerations of order up to 2l-1, thus pointing at potential dynamical instability.
|
https://arxiv.org/abs/2601.09761
|
Academic Papers
|
svg
|
0ad5a0b6de366bb67da25df635ecdf656728a36da65d25742a07d31ad4e08385
|
2026-01-16T00:00:00-05:00
|
DC response of an interferometer topology with an L-shaped cavity: a tabletop study
|
arXiv:2601.09764v1 Announce Type: new Abstract: A new interferometer topology for kilohertz gravitational-wave detection was recently proposed in [Zhang et al. Phys. Rev. X 13, 021019 (2023)]. The design is based on an L-shaped optical cavity pumped through a Sagnac-like vortex. We report a tabletop experiment that characterizes the interferometer's optical response near DC. When the laser frequency is locked to the resonance of the L-shaped cavity, we observe that the cavity input coupler becomes effectively transparent, yielding a simple Michelson-like response. Moreover, the Sagnac vortex separates into upper and lower paths, which behave as two independent pumping paths driving the cavity. These observations are in agreement with theoretical predictions. Our results provide an intuitive physical picture of this interferometer topology and offer insight into its lock acquisition strategy.
|
https://arxiv.org/abs/2601.09764
|
Academic Papers
|
svg
|
3806c8ad9ca3678172ba7d4cdcde28462438f04334b606db735cb43944a94b59
|
2026-01-16T00:00:00-05:00
|
Free-space Optical Diffraction and the Fisher Information
|
arXiv:2601.09797v1 Announce Type: new Abstract: Using the transport-of-intensity approach for free-space optical propagation in the paraxial regime, we show that diffraction is fundamentally related to the Fisher information associated with models of the transverse intensity distribution. By interpreting intensity as a probability density, we show that a) free-space diffraction will always act to flatten the intensity distribution as the beam propagates, and consequently b) diffraction will monotonically minimize the Fisher Information with respect to any parameterization of the intensity distribution model that depends on propagation distance.
|
https://arxiv.org/abs/2601.09797
|
Academic Papers
|
svg
|
a92ee9a233a8550481677947f461d2c172bbce7fe7455a790544535efc1ac045
|
2026-01-16T00:00:00-05:00
|
Programmable on-chip synthesis and reconstruction of partially coherent two-mode optical fields
|
arXiv:2601.09802v1 Announce Type: new Abstract: Partially coherent light is typically studied in the context of freely propagating continuous fields. Recent developments have indicated the existence of a `coherence advantage' in multimode optical communications, where partially coherent light outperforms coherent light. However, exploiting partial coherence in such applications requires manipulating multimode field coherence in programmable on-chip platforms. We present here the first example of on-chip synthesis and characterization of two-mode optical fields in an integrated on-chip hexagonal mesh of Mach-Zehnder interferometers. Starting with incoherent two-mode light, we adjust the degree of coherence on the chip with non-unitary transformations, construct $2\times2$ unitary transformations to synthesize prescribed coherence matrices, and reconstruct the coherence matrices via measurements of the spatial Stokes parameters. These results indicate the possibility of deploying programmable photonics for producing large-dimensional structured partially coherent light for applications in communications, cryptography, sensing, and spectroscopy.
|
https://arxiv.org/abs/2601.09802
|
Academic Papers
|
svg
|
b44f9c8055024f573c6c6f9acbfd752d16fb730fc4f8d810dc4d0ba93c2c263d
|
2026-01-16T00:00:00-05:00
|
RLC Parameters of a Two-Wire Line with the Finite Element Method
|
arXiv:2601.09829v1 Announce Type: new Abstract: This tutorial paper shows how to compute the DC (or low-frequency) resistance, inductance and capacitance of a pair of parallel wires using the finite element method. A three-dimensional infinite domain (open boundary) modeling of electrostatic and magnetostatic fields is presented, along with the electrokinetic formulation for the current flow inside the wires. The effects of the insulation and of a proposed physical defect in the wires are also considered. The open-source ONELAB software is used to perform the simulations and the code listing is provided. Comparisons using analytical models (when applicable) and the Altair Flux software are performed to help validate the simulations.
|
https://arxiv.org/abs/2601.09829
|
Academic Papers
|
svg
|
b717da245f7a8064056b95dfdff0630b7645b529b74a1d9eeafb96b0abe86226
|
2026-01-16T00:00:00-05:00
|
Wavefront Engineering for Scintillation-Based Imaging
|
arXiv:2601.09830v1 Announce Type: new Abstract: Recent research in nanophotonics for scintillation-based imaging has demonstrated promising improvements in scintillator performance. In parallel, advances in nanophotonics have enabled wavefront control through metasurfaces, a capability that has transformed fields such as microscopy by allowing tailored control of optical propagation. This naturally raises the following question, which we address in this perspective: can wavefront-control strategies be leveraged to improve scintillation-based imaging? To answer this question, we explore nanophotonic- and metasurface-enabled wavefront control in scintillators to mitigate image blurring arising from their intrinsically diffuse light emission. While depth-of-field extension in scintillation faces fundamental limitations absent in microscopy, this approach reveals promising avenues, including stacked scintillators, selective spatial-frequency enhancement, and X-ray energy-dependent imaging. These results clarify the key distinctions in adapting wavefront engineering to scintillation and its potential to enable tailored detection strategies.
|
https://arxiv.org/abs/2601.09830
|
Academic Papers
|
svg
|
6fd5f45de7c9bd91dcd3312ddcd05ec27137bda589c9257f3858747b47a7cf29
|
2026-01-16T00:00:00-05:00
|
Stability and Vibrations of Proteins in Vacuum and Water: Bridging Quantum Accuracy and Force-Field Efficiency
|
arXiv:2601.09845v1 Announce Type: new Abstract: Predicting biomolecular thermodynamics and spectroscopy requires accurate relative energies of metastable states and local curvatures on the potential-energy surface. We show that the general-purpose SO3LR machine-learned force field (MLFF) reproduces PBE0+MBD density-functional theory with unprecedented fidelity across bio-relevant molecules spanning sizes and complexities far beyond its training dataset. For 23 small molecules, SO3LR captures harmonic and anharmonic vibrational features, including frequencies, displacement patterns, and IR spectra. We perform detailed dynamical studies of the amino acid oF-Phe+, folding of the alanine-15 peptide, and assembly of monomeric p53 transactivation domains into tetramers, in vacuum and water. SO3LR consistently reproduces DFT-level potential-energy surfaces, vibrational densities of states, and mode eigenvectors, capturing anharmonicity, polarization, and medium-range environment-driven interactions crucial for proteins. Our results establish that MLFF-driven dynamics provide a quantum-accurate picture of metastable minima and vibrational properties, achieving DFT-level accuracy at force-field computational cost and opening new possibilities for the computational study of biomolecules.
|
https://arxiv.org/abs/2601.09845
|
Academic Papers
|
svg
|
233e78ca9b7d5b5356090db6a8b56ebfe86c05e05e3e54cb09ebe654eb1431a5
|
2026-01-16T00:00:00-05:00
|
Development of a glow-discharge ion-trap instrument for measuring effective radiative-association rate coefficients
|
arXiv:2601.09862v1 Announce Type: new Abstract: The ability to directly measure radiative-association rate coefficients for reactions between ions and neutral molecules has long challenged chemical physics laboratories, yet radiative association is one of the most important processes occurring in cold, diffuse regions of space. A reaction kinetics instrument has been developed for the investigation of ion--molecule radiative-association reactions, aimed at measuring slow, effective reaction rate coefficients for species relevant to astrophysical objects. The instrument consists of a glow-discharge ion source for production of bright and stable ion currents, a quadrupole mass filter for mass selection and detection, and a quadrupole ion trap capable of trapping reactants and products for the long times needed to measure slow kinetics. The performance and adaptability of the glow-discharge ion source has been evaluated using several configurations. To assess the feasibility of measuring reaction rate coefficients, the reaction of Ag$^{+}$ and O$_{2}$ was studied under pseudo-first-order conditions in the ion trap at room temperature. We present the first pressure-dependent study of this reaction and extract a lower limit of $1 \times 10^{-15}$ cm$^3$ molecule$^{-1}$ s$^{-1}$ for the Ag$^{+}$ + O$_{2}$ effective radiative-association rate coefficient. Measurements of effective radiative-association rate coefficients are possible for diverse atomic and molecular ions that react with neutral molecules over a range of rates in this versatile new instrument.
|
https://arxiv.org/abs/2601.09862
|
Academic Papers
|
svg
|
60b5e38511a431e0fade9bdabf91649913fb5b3a5e39268acfae1cd6f9dc9a05
|
2026-01-16T00:00:00-05:00
|
Studying Impact and Intent of Design: Conjecture Mapping for Affect-Centered Analysis
|
arXiv:2601.09878v1 Announce Type: new Abstract: Physics education researchers have argued that authentic physics education includes computation as part of a physics student's training, and many parties have made efforts towards this goal. However, most research on this teaching modality has centered cognitive impacts rather than affective impacts, so little is known about the affective outcomes of holistically integrating computation into physics courses. To address that need, we present a case study of a multi-day activity within a computationally integrated modern physics laboratory course. Based on course observations and interviews with the professor of and a student in the course, we distinguish between the professor's intent behind the activity design and the impact on the student's physics computational literacy and physics identity with a novel modification of conjecture mapping that explicates how a student enacts the professor's expectations. In doing so, we highlight the methodological suitability of conjecture mapping for comparing the intent and impact of curricular design and explicate the specific misalignments that led to different affective outcomes than intended.
|
https://arxiv.org/abs/2601.09878
|
Academic Papers
|
svg
|
e71a530d1fefaee14830dc448c357b5e460beb5fb0bc86c31941b0bd359d7c88
|
2026-01-16T00:00:00-05:00
|
Variable coherence model for free-electron laser pulses
|
arXiv:2601.09885v1 Announce Type: new Abstract: We introduce the variable coherence model (VCM) for simulating free-electron laser (FEL) pulses generated through self-amplified spontaneous emission. Building on the established partial coherence model of [T. Pfeifer et. al, Opt. Lett. 35, 3441 (2010)], we demonstrate that the implementation of a variable coherence width allows for continuous control over the pulses' characteristic noise, while keeping the average pulse parameters such as the bandwidth fixed. We demonstrate this through systematic statistical analyses of the intensity and number of sub-pulses in VCM pulses, in both time and frequency. In particular, we analyze how the sub-pulse statistics are affected by the coherence width parameter. We perform our analyses across three distinct regimes of FEL parameters and demonstrate how the VCM can generate pulses that range from maximally random to fully coherent. Finally, we illustrate the effect of the VCM variable coherence width on an absorption simulation.
|
https://arxiv.org/abs/2601.09885
|
Academic Papers
|
svg
|
627d1e0f62d28c6587785cb846c1d80643659e55b7fdc30113702ebc1c6fa090
|
2026-01-16T00:00:00-05:00
|
Astronomy in the Islamic World: a European Perspective
|
arXiv:2601.09899v1 Announce Type: new Abstract: Mathematical and astronomical achievements of the Islamic World during its golden era are briefly exposed. Thie article is based on the invited talk delivered remotely at the ICRANet-Isfahan Astronomical meeting, November 2-5, 2021, which, in turn, reproduces major parts of one of the chapters of my book ``Our Celestial Clockwork'', published recently (2021) by the World Scientific.
|
https://arxiv.org/abs/2601.09899
|
Academic Papers
|
svg
|
b72f0b9dae984737aae4c8ec5d1981adffed841498f64befe8de38ada0f5a91b
|
2026-01-16T00:00:00-05:00
|
A feasibility study for a Doppler Reflectometer System in the JT-60SA tokamak
|
arXiv:2601.09906v1 Announce Type: new Abstract: In this work we present a study on the viability and practicality of installing a Doppler reflectometer (DR) system in the JT-60SA advanced tokamak. First, we discuss its scientific scope in the context of the JT-60SA research plan. We identify a number of fields in which a DR would be very relevant for the accomplishment of said plan and outline a scientific program for the diagnostic. Then, starting from a number of design hypothesis, we use a ray tracing code to carry out a feasibility study for a number of relevant scenarios and identify a geometric solution for the installation of a DR such that both core and edge can be probed in the prescribed wave number range, thus achieving the proposed scientific objectives. Finally, we perform a preliminary discussion on the different possibilities for a conceptual design (including a minimum viable system and a baseline system) and their requirements in terms of components and space. We conclude that a viable conceptual design could be carried out using a small fraction of a horizontal port, leaving room for additional diagnostic systems.
|
https://arxiv.org/abs/2601.09906
|
Academic Papers
|
svg
|
8c9d50dd30641a13f040dd99704126886401ca5525740a104803da10f8d0601f
|
2026-01-16T00:00:00-05:00
|
A model for water transport in the membrane and an impedance spectroscopy study of the effect of relative humidity on PEM fuel cell parameters
|
arXiv:2601.09915v1 Announce Type: new Abstract: Effective water management is essential for the optimal performance of PEM fuel cells. We have developed an impedance model for liquid water transport through the membrane and coupled it with the two-phase model for cathode side impedance. The complete model was fitted to experimental spectra measured at anode/cathode relative humidities (RH) of 32/32\%, 50/50\% and 100/100\% within a current density range of 100 to 1000 mA cm$^{-2}$ and an air flow stoichiometry of 2. Cathode catalyst layer (CCL) saturation decreases with current density due to a growing liquid pressure gradient. For all RH values, the CCL oxygen diffusivity increases dramatically with cell current due to progressive involvement of larger pores into the proton current conversion. Higher RH leads to higher double layer capacitance, which indicates that liquid water increases the electrochemically active surface area.
|
https://arxiv.org/abs/2601.09915
|
Academic Papers
|
svg
|
71e05b58ddca0cedc2c29fa522a1dfb85cf90c55834d06f63da657cadf06301c
|
2026-01-16T00:00:00-05:00
|
Near-Unity-Efficiency Gas Gratings for Ultraviolet, Visible, and Infrared High-Power Lasers
|
arXiv:2601.09963v1 Announce Type: new Abstract: Interfering deep ultraviolet (DUV) lasers can induce substantial density modulations in an ozone-doped gas flow via photochemical reactions, creating volume diffraction gratings. These transient optics are immune to target debris and shrapnel and feature orders-of-magnitude higher damage thresholds than conventional solid optics, providing a promising method for efficiently manipulating high-energy lasers. In this work, we describe gas gratings that can efficiently diffract probe beams across a variety of wavelengths and pulse durations, ranging from deep ultraviolet to near-infrared and from nanosecond to femtosecond, achieving a full beam diffraction efficiency up to 99% while preserving the focusability and wavefront quality. In addition, we present a comprehensive characterization of the performance of the gas gratings under various experimental conditions, including imprint fluence, gas composition, and grating geometries, showing significant enhancement of this process with the addition of carbon dioxide. We also demonstrate stable performance over hours of operation. Our results validate a previously developed theoretical model and suggest optimal parameters to efficiently scale gas gratings to high-energy applications.
|
https://arxiv.org/abs/2601.09963
|
Academic Papers
|
svg
|
7f6dcc7c3151eadd93a83c7adb4ad953b67298979fbe8c2f658e3cb6ab71ea77
|
2026-01-16T00:00:00-05:00
|
aiPlato: A Novel AI Tutoring and Step-wise Feedback System for Physics Homework
|
arXiv:2601.09965v1 Announce Type: new Abstract: This exploratory study examines the classroom deployment of aiPlato, an AI-enabled homework platform, in a large introductory physics course at the University of Texas at Arlington. Designed to support open-ended problem solving, aiPlato provides step-wise feedback and iterative guidance through tools such as "Evaluate My Work" and "AI Tutor Chat", while preserving opportunities for productive struggle. Over four optional extra-credit assignments, the platform captured detailed student interaction data, which were analyzed alongside course performance and end-of-semester survey responses. We examine how students engaged with different feedback tools, whether engagement patterns were associated with performance on the cumulative final exam, and how students perceived the platform's usability and learning value. Students who engaged more frequently with aiPlato tended to achieve higher final exam scores, with a mean difference corresponding to a standardized effect size of approximately 0.81 between high and low engagement groups after controlling for prior academic performance. Usage patterns and survey responses indicate that students primarily relied on iterative, formative feedback rather than solution-revealing assistance. As a quasi-experimental pilot study, these findings do not establish causality and may reflect self-selection effects. Nonetheless, the results demonstrate the feasibility of integrating AI-mediated, step-wise feedback into authentic physics homework and motivate future controlled studies of AI-assisted tutoring systems.
|
https://arxiv.org/abs/2601.09965
|
Academic Papers
|
svg
|
55309ace2be936a5bd1f95e34d9e24b69615f8688fc7b94fc35239e3f82abdb9
|
2026-01-16T00:00:00-05:00
|
Gatekeeping: a Partial History of Cold Fusion
|
arXiv:2601.09996v1 Announce Type: new Abstract: One of the most public episodes of gatekeeping in modern science was the case of so-called 'cold fusion'. At a news conference in 1989 the electrochemists Martin Fleischmann and Stanley Pons announced that they had found evidence of nuclear fusion in palladium electrodes loaded with deuterium. There was worldwide interest. Many groups sought to reproduce the results, most unsuccessfully. Within months, the prevailing view became strongly negative. The claims of Fleischmann and Pons came to be regarded as disreputable, as well as false. As the Caltech physicist David Goldstein put it, cold fusion became 'a pariah field, cast out by the scientific establishment' (Goldstein 1994). The case would already be interesting for students of gatekeeping if the story had ended at that point. Even more interestingly, however, the field survived and persisted. It has been enjoying a modest renaissance, with recent government funding both in the US and the EU. This piece offers an opinionated introduction to cold fusion as a case study of scientific gatekeeping, discussing both its early and recent history
|
https://arxiv.org/abs/2601.09996
|
Academic Papers
|
svg
|
606b273ebb218ee2f1cd198e493699bdf2064b7c03f78f54e297e2742c694d95
|
2026-01-16T00:00:00-05:00
|
Hybrid Quantum Algorithms for Computational Chemistry: Application to the Pyridine-Li ion Complex
|
arXiv:2601.10002v1 Announce Type: new Abstract: Accurately capturing electron correlation in large-scale molecular systems remains one of the foremost challenges in quantum chemistry and a primary driver for the development of quantum algorithms. Classical configuration-interaction methods, while rigorous, suffer from exponential scaling, rendering them impractical for large or strongly correlated systems. Overcoming this limitation is central to realizing the promise of quantum computing in chemistry. Here, we investigate the pyridine-Li ion complex using three quantum algorithms: the variational quantum eigensolver (VQE), the subspace quantum diagonalization (SQD) method, and the recently introduced handover iterative VQE (HI-VQE). Our results demonstrate how new generations of hybrid quantum-classical frameworks overcome the scalability and noise sensitivity that constrain conventional VQE approaches. SQD and HI-VQE achieve ground-state energy calculations for problem sizes inaccessible to classical computation, marking a clear advance toward quantum advantage. In particular, HI-VQE enables calculations within active spaces as large as (24e,22o), requiring 44 qubits-well beyond the reach of classical CASCI and VQE. This capability provides a systematic pathway for incorporating increasing numbers of electrons into quantum treatment, thereby approaching exact molecular energies. Importantly, both SQD and HI-VQE exhibit robustness against hardware noise, a critical improvement over earlier approaches. By enabling quantum simulations of molecular systems previously deemed intractable, SQD and HI-VQE offer a realistic route toward practical quantum advantage in computational chemistry. The comparison between HI-VQE and SQD shows that optimizing circuit parameters is crucial for accurate simulation.
|
https://arxiv.org/abs/2601.10002
|
Academic Papers
|
svg
|
8f630e5051216198703b23e6e1db86915c6ab4c0c5ef406d4707fcbbd0742f82
|
2026-01-16T00:00:00-05:00
|
Same Activity, Divergent Impacts: Representing Paths Towards Physics Computational Literacy and Physics Identity with Conjecture Mapping-Based Narrative Analysis
|
arXiv:2601.10005v1 Announce Type: new Abstract: Integrating computation into physics teaching is a curricular move that, at present, has been predominately studied for its cognitive impacts. However, if this modality of instruction shifts how students engage with physics, we argue there is room for students to redefine what it means to do physics and how they perceive themselves relative to the field. To investigate this, we situate a comparative case study in the context of a computationally integrated physics course. We study two students' experiences with a multi-day activity to understand how and why they came to affectively divergent self-perceptions. We propose a modified use of conjecture mapping to visualize the production of affective outcomes and connect narrative analysis to activity design. Our analysis highlights how different interpretations of and engagement with activity design reflect students' epistemic framing of code, which, in turn, drives engagement with scaffolding in manners that shape self-perception.
|
https://arxiv.org/abs/2601.10005
|
Academic Papers
|
svg
|
e14efa1e89c7e7e0d003d463c89cae0d983bcf2cd59fdd7adec0cca7656a4923
|
2026-01-16T00:00:00-05:00
|
Effects of parallel magnetic fields on sheaths near biased electrodes in a highly collisional Z-pinch plasma
|
arXiv:2601.10039v1 Announce Type: new Abstract: Sheath formation near biased electrodes in magnetic fields parallel to the wall is an understudied topic, especially within the context of Z-pinch fusion experiments. We perform 1X-2V Boltzmann-Poisson simulations of an axial cut at the pinch radius of a Z-pinch plasma between two biased electrodes with a magnetic field parallel to the wall. The collision frequencies are artificially increased to enhance thermalization of the plasma in the smaller simulation domain versus the actual experiment size; this increases the perpendicular mobility and partially de-magnetizes the ions resulting in non-monotonic sheath profiles with the potential increasing away from the wall to a peak before decaying. A classical sheath forms within an electron gyroradius from the wall not due to the natural thermal motion of the electrons, but due to the magnetized electrons gyrating into the wall; therefore, the sheath structure does not significantly change with bias potential or between electrodes. With increasing bias potential, a current is induced perpendicular to the wall due to changes in ion flow, differing from unmagnetized cases where current is induced by changes in electron flow. The magnetic field acts as a high resistivity with the perpendicular current density being three orders of magnitude lower than unmagnetized theoretical predictions. There is, however, significant flow parallel to the wall from the force balance between the pressure tensor and Lorentz force. These parallel flows induce a parallel current density three orders of magnitude larger than the perpendicular current density.
|
https://arxiv.org/abs/2601.10039
|
Academic Papers
|
svg
|
3fb3a167ab2db5f1294b1781b3493c6d5215dda91cf0b29871117dd0489a9fc4
|
2026-01-16T00:00:00-05:00
|
Collective behavior based on agent-environment interactions
|
arXiv:2601.10046v1 Announce Type: new Abstract: We present a model of active particles interacting through a dynamic, heterogeneous environment, leading to emergent collective behaviors without direct agent-to-agent communication. Expanding the resource-dependent framework introduced in Briozzo et al., 2025, arXiv:2512.08762, agents perform a persistent random walk combined with chemotaxis, directing toward nutrient-rich patches, whose resources are generated by logistic regrowth. We identify distinct phases of collective organization, ranging from disordered gas-like states to polar traveling waves and nematic independent clusters, depending on the interplay between chemotactic sensitivity and angular noise. The system exhibits spontaneous symmetry breaking and density waves driven purely by the coupling between population dynamics (birth-death processes) and environmental feedback. Our results bridge active matter physics and movement ecology, demonstrating that complex spatiotemporal patterns can arise without direct interaction between agents, but solely from the maximization of resource intake in a reactive environment.
|
https://arxiv.org/abs/2601.10046
|
Academic Papers
|
svg
|
921181afeb8787c7efdde09bf861d9a27f260fd98c7275948289540645fc0776
|
2026-01-16T00:00:00-05:00
|
Comparative study of equilibrium and non-equilibrium predictions by different models for a hypersonic cone at high-altitude
|
arXiv:2601.10050v1 Announce Type: new Abstract: Targeting a cone with the half-angle as 10-deg at M = 27 and H = 72 km, simulations were conducted comparatively to analyze the predictions by different equilibrium and non-equilibrium gas models. Following validation and grid studies, systematic comparisons on aerodynamic performance, flow structures, and characteristic distributions were performed. The key findings are: (1) While the overall flow structures are broadly similar, discrepancies exist in the features at the base locations, e.g., the diverse high-temperature distributions. Notably, the vibrational temperatures distribute differently under slip and non-slip boundary conditions near the wall; (2) The equilibrium gas model predicts higher drag coefficient, wall heat flux, and skin friction than those of non-equilibrium models. Predictions also vary among the non-equilibrium models themselves. Specifically, compared to the three-temperature model, the one- and two-temperature models predict larger drag coefficients with the relative difference exceeding 5%. Nevertheless, the results from the three-temperature model with and without slip conditions are largely consistent; (3) The disparities between equilibrium and non-equilibrium characteristics are primarily manifested in the shock layer and wake regions. Within these regions, the overall temperature for the equilibrium gas is lower than that for the non-equilibrium cases, while in the latter specific non-equilibrium features are distinctly exhibited, e.g., the translational-rotational temperature is generally higher than that from the one-temperature model, and the vibrational-electronic temperature shows the opposite trend. Notably, in the slip flow within the three-temperature model, the translational-rotational temperature is higher and, particularly, the vibrational temperature is even larger than counterparts of the non-slip flows near the wall and base center line.
|
https://arxiv.org/abs/2601.10050
|
Academic Papers
|
svg
|
aa3401a49ab1a7aa465c33cc0728d2522e238780fe6b2f9e94de4a8ba143240b
|
2026-01-16T00:00:00-05:00
|
Interference-governed electromagnetic-thermal coupling and heat transport in pulse EUV-irradiated multilayer nanofilms
|
arXiv:2601.10069v1 Announce Type: new Abstract: Mo-Si multilayer mirrors are central to extreme ultraviolet lithography, where nanoscale optical interference and heat accumulation together constrain reflectivity and operational stability. Here we develop an analytical electromagnetic-thermal coupling model that directly links transfer-matrix-based interference-controlled energy deposition with transient heat conduction in EUV-irradiated multilayers. The model reveals a fundamental trade-off whereby increasing the multilayer period number enhances reflectivity but simultaneously elevates temperature by impeding heat dissipation. Interference-driven volumetric absorption further gives rise to pronounced axial temperature gradients and a post-pulse downward migration of the heat-flux maximum, a delayed-heating effect inaccessible to conventional surface-flux-based models. Systematic analysis establishes scaling laws connecting interfacial thermal resistance, beam size, and incident energy density to thermal confinement and temperature rise. By incorporating interfacial compaction kinetics, the model enables a quantitative assessment of mirror lifetime. This work offers a theoretical tool for thermal-optical co-design of multilayer nanostructures including EUV mirrors under pulsed irradiation across a wide spectral range.
|
https://arxiv.org/abs/2601.10069
|
Academic Papers
|
svg
|
ad7e7792f59e486994b45c6cb28234e32b94f23a5cd5e6085f49fb9b5e73523f
|
2026-01-16T00:00:00-05:00
|
Effect of hole pitch reduction on electron transport and diffusion: A comparative simulation study of Triple GEM detectors
|
arXiv:2601.10139v1 Announce Type: new Abstract: Advances in fabrication techniques and high-performance electronics have facilitated the development of fine-pitch Gas Electron Multipliers (GEMs). Earlier experimental and simulation findings suggest that these reduced-pitch GEMs can outperform the standard configuration in terms of effective gain, collection efficiency, and position resolution. However, a noticeable fraction of avalanche electrons is lost within the GEM systems, resulting in a degradation of charge collection efficiency. Therefore, a comprehensive simulation-based study is essential to provide deeper insights into the extent of degradation and its contributing factors. In this context, we employ ANSYS and Garfield++ to model the Triple GEM detectors with reduced pitch sizes of 90 and 60 $\mu$m, and perform a comparative performance analysis with the standard configuration (pitch size: 140 $\mu$m). At first, the simulation framework is validated by comparing the results of the standard configuration with available experimental data and previously reported simulation outcomes. Despite the characteristic gain offset, the framework remains physically consistent and reliable in capturing microscopic avalanche dynamics, reproducing the experimental trend. Following validation, we investigate electron losses at the metal electrodes and within the Kapton holes, electron transmission through the transfer and induction regions, electron diffusion on the induction electrode, and the overall collection efficiency. These parameters are analyzed as functions of GEM potential, outer hole diameter, inner hole diameter, Kapton thickness, metal thickness, and gas composition, thereby offering insights for designing efficient GEM detectors.
|
https://arxiv.org/abs/2601.10139
|
Academic Papers
|
svg
|
342242fd36a9ab04ed505f8a8954466252ae3cfa21acb7d3de9bf9794f976473
|
2026-01-16T00:00:00-05:00
|
Systemically Designed Degrees for Real-World Challenges: A case study on Physics curriculum design at Loughborough University
|
arXiv:2601.10219v1 Announce Type: new Abstract: We present a ground-up redesign of the undergraduate physics degree at Loughborough University, driven by the principle of authenticity in academic and industrial practice. Departing from conventional incremental reforms, we adopt a systems-engineering approach to programme-level curriculum design, treating the degree as an integrated system with verifiable performance. This methodology aligns stakeholder-derived requirements with vertically-integrated threads in theory, computation, laboratory practice, and professional skills. We demonstrate that this approach enables students to achieve levels of disciplinary and cross-disciplinary competence beyond those typically expected at undergraduate level. Outcomes are supported by graduate destinations, enhanced student performance, and positive external evaluations, including national accreditation. Our results suggest that rigorous, system-level curriculum design can yield transformational gains in both capability and confidence.
|
https://arxiv.org/abs/2601.10219
|
Academic Papers
|
svg
|
91c0193a461fa7f852712a52ab754c489faf39a34bed97307565a5a035e659e7
|
2026-01-16T00:00:00-05:00
|
Volume penalization method for simulating flows around a rotating solid with multiple reference frame and sliding mesh
|
arXiv:2601.10230v1 Announce Type: new Abstract: Despite the significant role of turbomachinery in fluid-based energy transfer, precise simulation of rotating solid objects with complex geometry is a challenging task. In the present study, the volume penalization method (VPM) is combined with multiple reference frame (MRF) and sliding mesh (SLM), respectively, so as to develop immersed-boundary approaches for simulating flows around a rotating solid. The level-set function is adopted to represent arbitrary geometries embedded in Cartesian grids. The VPM body-forcing terms in the momentum equation are proposed for MRF and SLM, respectively, so as to build unified governing equations for both fluid and solid regions. The flows around a rotating cuboid under various rotating speeds are simulated by the present schemes, namely, VPM with MRF, and VPM with SLM, and compared to corresponding simulations by the body-fitted method (BFM). The results suggest the relative deviations of predicted pressure drop and torque between the present VPM and BFM are around 5%, demonstrating the validity of the present VPM.
|
https://arxiv.org/abs/2601.10230
|
Academic Papers
|
svg
|
cfd4502e0b7c8f11b5dc6c1ab2fa37950ecf7174ba184151cd5686b6cea4aff6
|
2026-01-16T00:00:00-05:00
|
An Exact Energy Conservation Law for Magneto-Optical Nanoparticles
|
arXiv:2601.10255v1 Announce Type: new Abstract: Energy conservation imposes fundamental bounds on the polarizabilities of nanoparticles (NPs). While such bounds are well established for isotropic and bianisotropic NPs, they remain unexplored for magneto-optical NPs. Here, we derive the exact energy-conservation law governing the electric and magnetic dipolar response of axially symmetric magneto-optical NPs under general illumination conditions and arbitrary external magnetic fields. Two central results follow from energy conservation: (i) purely magneto-optical scattering, where the non-magnetic polarizability vanishes, is fundamentally forbidden, and (ii) strong magneto-optical scattering regimes, in which the magneto-optical polarizability dominates, are intriguingly allowed.
|
https://arxiv.org/abs/2601.10255
|
Academic Papers
|
svg
|
0a0d4cb53eebce6a61e94261fdf46d82adc41addd621afef67e44a3e5e3536ef
|
2026-01-16T00:00:00-05:00
|
Pulse thermal imaging of FUHAO bronze artifact
|
arXiv:2601.10265v1 Announce Type: new Abstract: The accurate identification of historical restoration traces and material degradation is essential for the scientific preservation of ancient bronzes. In this study, the prestigious FUHAO bronze artifact (late Shang period, 13th-11th century BCE) was non-destructively examined using pulsed thermal imaging (PT). By combining single- and double-layer heat conduction models with Thermal Tomography (TT), this approach allowed for precise spatial localization of repair crevices, patches, and filler materials, while also distinguishing restorative interventions from the original bronze substrate. The artifact was revealed to have been assembled from multiple fragments, exhibiting uneven surface corrosion and clear evidence of prior conservation. The results not only provide direct insights for conservation strategy and historical interpretation but also demonstrate the capability of pulsed thermal imaging as an effective diagnostic tool for the integrated surface and subsurface assessment of cultural heritage objects.
|
https://arxiv.org/abs/2601.10265
|
Academic Papers
|
svg
|
7688efbb45c27e533489626269d78e5685da6737af680f34a99d99d5c58aeb2b
|
2026-01-16T00:00:00-05:00
|
Nonadiabatic couplings drive ultrafast, mode-selective intramolecular vibrational energy redistribution in flavins
|
arXiv:2601.10273v1 Announce Type: new Abstract: Flavins are the chromophores in several blue-light-sensitive photoreceptor proteins and act as redox cofactors in many enzymes relevant for biological processes. Despite their biological relevance and numerous, detailed optical investigations of their photophysical properties, the ultrafast nonequilibrium dynamics of their elementary optical excitations are not yet fully known. Here, we use ultrafast coherent vibrational spectroscopy with 10-fs time resolution in the 450-nm spectral range to study their excited state coherent vibrational dynamics. We observe that coherent wavepacket motion along high-frequency C-C stretching modes with ~ 20-fs period is rapidly damped on a 20-fs timescale. In contrast, coherent motion along several low-frequency modes persists much longer. We attribute this to a mode-selective intramolecular vibrational energy redistribution driven by nonadiabatic couplings between the optical bright state and a close-lying dark electronic state, in accordance with model calculations. Our results may be of relevance for the formation of long-lived radical pair states in magnetic-field sensitive proteins.
|
https://arxiv.org/abs/2601.10273
|
Academic Papers
|
svg
|
f75b55f3d1746d29d8c891a7300cb1bc2b8cde54e4884f3677ee4574d32a6e0e
|
2026-01-16T00:00:00-05:00
|
Model-Driven GPR Inversion Network With Surrogate Forward Solver
|
arXiv:2601.10284v1 Announce Type: new Abstract: Data-driven deep learning is considered a promising solution for ground-penetrating radar (GPR) full-waveform inversion (FWI), while its generalization ability is limited due to the heavy reliance on abundant labeled samples. In contrast, Deep unfolding network (DUN) usually exhibits better generalization by integrating model-driven and data-driven approaches, yet its application to GPR FWI remains challenging due to the high computational cost associated with forward simulations. In this paper, we integrate a deep learning-based (DL-based) forward solver within an unfolding framework to form a fully neural-network-based architecture, UA-Net, for GPR FWI. The forward solver rapidly predicts B-scans given permittivity and conductivity models and enables automatic differentiation to compute gradients for inversion. In the inversion stage, an optimization process based on the Alternating Direction Method of Multipliers (ADMM) is unfolded into a multi-stage network with three interconnected modules: data fitting, regularization, and multiplier update. Specifically, the regularization module is trained end-to-end for adaptive learning of sparse target features. Experimental results demonstrate that UA-Net outperforms classical FWI and data-driven methods in reconstruction accuracy. Moreover, by employing transfer learning to fine-tune the network, UA-Net can be effectively applied to field data and produce reliable results.
|
https://arxiv.org/abs/2601.10284
|
Academic Papers
|
svg
|
228333a96e4ca1136cc4ae68e7b91f445b4146f39623747f830b9b5428d88637
|
2026-01-16T00:00:00-05:00
|
Quantum bianisotropy in light-matter interaction
|
arXiv:2601.10287v1 Announce Type: new Abstract: Quantum bianisotropy and chirality are fundamental concepts in light matter interaction that describe how materials with broken symmetries respond to electromagnetic fields at the level of macroscopic quantum electrodynamics. In quantum bianisotropy, magnetoelectric (ME) energy plays a critical role in mediating and enhancing light matter interactions. This concept is essential for bridging the gap between classical electromagnetics (where bianisotropy often involves field nonlocality) and quantum mechanics in metamaterials. The precise manipulation of a quantum emitter's properties at a subwavelength scale is due to near fields, which effectively function as a tunable environment. We show that the ME near field, interpreted as a structure combining the effect of bianisotropy (chirality) with a quantum atmosphere, is a nonMaxwellian field with spacetime symmetry breaking. Quantum ME fields arise from the dynamic modulation and topological coupling of magnetization and electric polarization within ME meta atoms, specific subwavelength structural elements with magnetic and dielectric subsystems in magnetic insulators.
|
https://arxiv.org/abs/2601.10287
|
Academic Papers
|
svg
|
0ff5c6dc808b7c2e3b7ede974e1a345c0bae7e0f6d7a1e1d6a2b7fd1f747274f
|
2026-01-16T00:00:00-05:00
|
Updated electrical design of the Diagnostic Neutral Beam Injector in RFX-mod2
|
arXiv:2601.10293v1 Announce Type: new Abstract: The Diagnostic Neutral Beam Injector of the RFX-mod2 experiment (Consorzio RFX, Padova) is expected to provide novel and significant information about the Reversed Field Pinch confinement of fusion plasmas. The injection of the hydrogen beam in the plasma will allow Charge Exchange Recombination Spectroscopy (CXRS) and Motional Stark Effect diagnostics (MSE) to measure several quantities: ion speed, ion temperature, impurity content, intensity and pitch of the magnetic field. The DNBI is of particular importance for allowing the determination of these quantities at the core of the plasma. The present DNBI, built by the Budker Institute of Plasma Physics, features an arc discharge H+ source, coupled to a 4-grid 50 keV acceleration system. The 50 ms, 5 A ion beam is neutralized by charge exchange by means of a gas target; residual ions are then deflected by a magnetic field before injection in the torus chamber. The beam can be modulated at maximum 250 Hz. The DNBI will undergo extraordinary maintenance and a structural upgrade to improve its reliability and safety. This contribution presents the latest upgrades of the electrical plants and of the control system of the DNBI.
|
https://arxiv.org/abs/2601.10293
|
Academic Papers
|
svg
|
6dc705d3761b652da7fc7f8d277eddc82e5ea72935fa5230fda01f1403d4f42f
|
2026-01-16T00:00:00-05:00
|
Design, Fabrication and Testing of a D-Shaped High Temperature Superconducting Magnet
|
arXiv:2601.10295v1 Announce Type: new Abstract: High-temperature technical superconductors are potential candidates for compact and high-field tokamak magnets. The demand for higher fusion power can be met with an on-axis high magnetic field due to toroidal magnets. An R&D activity has been initiated at the Institute for Plasma Research, India, to develop a compact D-shaped superconducting magnet utilizing REBCO high-temperature superconducting tapes. Under this initiative, a toroidal configuration with a major radius of 0.42 m, consisting of eight D-shaped, four poloidal field, and a central solenoid high-temperature superconducting magnets producing an on-axis toroidal magnetic field of 0.23 T has been conceptualized. The fabrication feasibility of a D-shaped coil for this toroidal configuration also envisaged using stacked high-temperature superconducting cable. In this paper, we report the design of a compact D-shaped coil, the fabrication of a long length HTS cable, a winding pack, and its integration with a cryogenic casing and vacuum enclosure. The winding pack terminations, joints, its interfacing with the power supply, and performance testing are also reported in this paper.
|
https://arxiv.org/abs/2601.10295
|
Academic Papers
|
svg
|
76523cf1d53e80dd81d0afcc01ebd25ddb5f9c53b0383a62ffed8e023c9ac755
|
2026-01-16T00:00:00-05:00
|
Molecular electrostatic potentials from machine learning models for dipole and quadrupole predictions
|
arXiv:2601.10320v1 Announce Type: new Abstract: The molecular electrostatic potential (MEP) is a key quantity for describing and predicting intermolecular and ion-molecule interactions. Here, we assess the ability of machine-learning (ML) models to infer the MEP, based on the equivariant graph-convolutional neural network architecture PiNet2 and trained on dipole and quadrupole moments. For the established QM9 dataset, we find that including the quadrupole contribution in the ML models substantially improves their ability to recover the MEP compared to dipole-only models. This trend is confirmed on the SPICE dataset, which spans a much broader region of organic chemical space. Together, this study underscores the central role of the quadrupole moment as a fitting target for ML models aiming at rapid access to the MEP.
|
https://arxiv.org/abs/2601.10320
|
Academic Papers
|
svg
|
8b80f40b3ad05818e40e6a984f1e27abf7ee31f59ef78ecdcdec480a48ffffbd
|
2026-01-16T00:00:00-05:00
|
Neural-network-based high-speed and high-definition full-field dynamic optical coherence tomography
|
arXiv:2601.10327v1 Announce Type: new Abstract: A neural-network (NN)-based method for high-speed, high-definition dynamic optical coherence tomography (DOCT) using full-field swept-source optical coherence microscopy (FF-SS-OCM) is demonstrated. FF-SS-OCM provides high-definition OCT images, but, particularly in DOCT imaging, it results in a significant enlargement of the data size and subsequently long data streaming and processing time, which prevents high-throughput imaging. We address this issue by introducing an NN-based DOCT method that generates high-definition logarithmic intensity variance (LIV) -based DOCT images from only four OCT volumes, whereas the conventional method required 32 volumes. The NN model successfully generates an LIV image that is qualitatively and quantitatively similar to the LIV image computed from 32 volumes. This approach significantly reduces data size, transfer time, and processing time for DOCT imaging by a factor of eight. Specifically, these were reduced from 42 GB to 5.3 GB, 7 min to 55 s, and 4 hours to 30 min, respectively.
|
https://arxiv.org/abs/2601.10327
|
Academic Papers
|
svg
|
899fe7d88acf0ac99f7c1ea45473fc75af9c89d982158fad32644b5fd6332c2e
|
2026-01-16T00:00:00-05:00
|
Radiation Shielding Performance of Different Concrete Materials: A Systematic Review
|
arXiv:2601.10336v1 Announce Type: new Abstract: Background: Concrete is one of the most-used material today in nuclear, medical, and industrial applications for radiation shielding due to its economic advantages and availability together with its structural performance. However, differences in the use of aggregates, density, and other additives affect radiation attenuation efficiency. It is therefore necessary to understand and compare shielding properties of various concrete formulations for the optimization of safety and performance in radiation-prone environments. Methods: Using Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, a literature search was performed across PubMed, Scopus, ScienceDirect, and Google Scholar. 17 peer-reviewed studies published between 2010 and 2025 were analysed systematically. Data was extracted based on material composition, density, radiation type, energy range, attenuation coefficients, and shielding efficiency. The obtained results were compared to find the trend in performance and optimization of the considered materials. Conclusion: Radiation shielding efficiency of concrete is dependent on its density, microstructural characteristics and type of aggregate. For superior performance in a mixed radiation field, Heavy and boron-rich additives can be added. Newly developed UHPCs and nano-engineered concretes are lightweight, durable, and environmentally friendly options for shielding materials compared to traditional ones. Further studies are needed to focus on the standardization of test methods, validation of long-term stability, and coupling computational modelling with experimental data in order to guide material design for applications featuring enhanced radiation shielding.
|
https://arxiv.org/abs/2601.10336
|
Academic Papers
|
svg
|
2309096b4679f8903481066770f521938d61b618872d5b131b702dbf8c2164e0
|
2026-01-16T00:00:00-05:00
|
Joint Bayesian inference of Earth's magnetic field and core surface flow on millennial timescales
|
arXiv:2601.10344v1 Announce Type: new Abstract: Understanding Earth's core dynamics over millennial timescales requires models that jointly describe the evolution of the geomagnetic field and core surface flow, while accommodating the sparse, irregular, and uncertain nature of archaeomagnetic and palaeomagnetic data. We present a new Bayesian core field and core flow modelling framework that utilises archaeo/palaeomagnetic data directly, combining a reduced stochastic representation of core surface dynamics derived from numerical geodynamo statistics with a probabilistic treatment of observational and chronological uncertainties. A key innovation is an efficient discrete marginalisation of age uncertainties, which avoids the convergence difficulties associated with co-estimating ages in high-dimensional Hamiltonian Monte Carlo inversions. The framework aims to reconstruct the coupled evolution of the geomagnetic field and core surface flow over the past 9000 years while preserving dynamical correlations implied by the prior geodynamo time series. Tests using synthetic data generated from an Earth-like geodynamo demonstrate that the method reliably recovers large-scale geomagnetic field variations and key aspects of core dynamics, including long-term westward drift and the evolution of planetary-scale eccentric gyres. These results show that, when combined with physically informed priors, archaeo/palaeomagnetic data can constrain millennial-scale core flow, paving the way for reconstructions based on real data.
|
https://arxiv.org/abs/2601.10344
|
Academic Papers
|
svg
|
974521d699dcfc796bfe36f635df907d6698206127d1e335bffda36e7a6fcbf6
|
2026-01-16T00:00:00-05:00
|
A compact Optical Liquid Argon Facility at Roma Tre
|
arXiv:2601.10363v1 Announce Type: new Abstract: In this paper we present a compact test facility for the measurement of optical properties of liquid argon as scintillation detector. The setup is under preparation at Roma Tre and it has a volume of 40 L liquid argon, which is liquefied from argon gas with a purity of $\ge 99.9999\%$ vol. To readout the scintillation photons from liquid argon with the highest intensity near 127 nm, we use the vacuum ultraviolet silicon photomultipliers from Hamamatsu. By submerging the photon detectors directly inside the liquid argon, we can eliminate the systematics from the wave length shifter and light guides which have been commonly used to detect the scintillation photons of liquid argon.
|
https://arxiv.org/abs/2601.10363
|
Academic Papers
|
svg
|
a7953e5fa11bf4c0d0132a38dc98212bc66cabaaa6ca91040124092b9f0748a9
|
2026-01-16T00:00:00-05:00
|
The Direct-Product Decomposition Approach for Symmetry Exploitation in Many-Body Methods in Case of Non-Abelian Point Groups
|
arXiv:2601.10371v1 Announce Type: new Abstract: We demonstrate for the specific case of $C_{3v}$ how the direct-product decomposition scheme for the treatment of symmetry in coupled-cluster (CC) calculations can be extended to non-Abelian point groups. We show that for the two-electron integrals and CC amplitudes a block structure can be obtained by resolving the reducible products of two irreducible representations into their irreducible representations. To deal with the necessary resorts of the ordering of the two-electron integrals and amplitudes, spin-adaptation, and the O(M$^5$) contractions (with M as the number of basis functions) of a CC calculation, we suggest a strategy that uses both the reduced and non-reduced representation of the corresponding quantities and switches back and forth between them. While the reduced representations are the ones used in the O(M$^6$) contractions, the other steps are better carried out in the non-reduced representation. Our pilot implementation of the CC singles and doubles method confirms in test calculations for NH$_3$ and PH$_3$ using different basis sets that significant savings (of more than 20 compared to treatments without symmetry and about 5 compared to treatments using $C_s$ symmetry) are possible and suggest that the exploitation of non-Abelian symmetry would render CC computations on large highly symmetric molecules possible
|
https://arxiv.org/abs/2601.10371
|
Academic Papers
|
svg
|
afe0f0cfd2d2b5ea8109216fce608ba6a9201d6ad17e375ef338a0d774e4573d
|
2026-01-16T00:00:00-05:00
|
Scale Collapse of Vortices at Porous-Fluid Interfaces
|
arXiv:2601.10396v1 Announce Type: new Abstract: The interaction between externally generated turbulence and porous media is central to many engineering and environmental flows, yet the fate of macroscale vortical structures at a porous/fluid interface remains uncharacterized. By numerically simulating the turbulent flow, we investigate the penetration, breakdown, and turbulence kinetic energy (TKE) transport of macroscale vortices impinging on porous matrices with high porosities $\phi$ = 0.80-0.95. For all porosities considered, macroscale vortices collapse abruptly at the porous interface and do not persist within the matrix, supporting the pore-scale prevalence of turbulence even under strong external forcing. Although vortex impingement injects TKE into the porous medium through turbulent transport at the interface, this supplied TKE is rapidly redistributed and dissipated as the flow reorganizes to satisfy pore-scale geometric constraints. Deeper within the porous layer, turbulence is sustained primarily by local shear production associated with pore-scale velocity gradients, and the internal flow becomes increasingly independent of upstream conditions. Variations in porosity modulate the relative balance between production and dissipation by altering geometric confinement and effective Reynolds number, but the dominant turbulent length scale within the porous matrix remains set by the pore size. These results demonstrate that porous media act as a robust geometric filter that enforces pore-scale-dominated turbulence regardless of external forcing.
|
https://arxiv.org/abs/2601.10396
|
Academic Papers
|
svg
|
7a4e147c52584a0afcab7dab144cc877fc7dc5278a2cc3dcf153385525eb34bd
|
2026-01-16T00:00:00-05:00
|
Wilson-Fisher renormalization of discrete gravity-capillary wave turbulence in viscous fluids
|
arXiv:2601.10400v1 Announce Type: new Abstract: We report an experimental realization of Wilson-Fisher renormalization in driven surface-wave turbulence across Newtonian fluids spanning nearly six decades in Raynolds number. Discrete capillary and gravity turbulence define two universality classes selected by interaction topology: triadic resonances for capillary waves and effectively tetradic scattering for gravity waves. Navier-Stokes viscosity is the relevant perturbation that renormalizes spectral transfer and terminates the cascade. The resulting framework predicts the Kolmogorov cutoff from the balance of nonlinear transfer and viscous damping, and Reynolds scaling of the integrated inertial spectral weight. Laser Doppler Vibrometry quantitatively confirms these renormalized scaling laws, establishing discrete gravity-capillary turbulence as a tunable laboratory for nonequilibrium crossoever criticality.
|
https://arxiv.org/abs/2601.10400
|
Academic Papers
|
svg
|
869e393b5ffa1c51e30790328c44e6040197ca6858e9dd3760482685509b3953
|
2026-01-16T00:00:00-05:00
|
Observation of Light-Driven Levitation Near Epsilon-Near-Zero Surfaces
|
arXiv:2601.10425v1 Announce Type: new Abstract: Optical manipulation of micro- and nanoparticles near surfaces is fundamental for applications in sensing and microfluidics, yet controlling particle-surface interactions remains challenging. Here we experimentally investigate light-induced forces on dielectric particles near epsilon-near-zero (ENZ) metamaterial surfaces using photonic force microscopy. By illuminating trapped particles with tunable visible light, we observe a wavelength-dependent repulsive force unique to ENZ surfaces, contrasting with the attractive forces near dielectric or metallic substrates. This repulsion peaks near the ENZ frequency and may be attributed to combined optical ENZ effects and thermophoretic forces. Our findings demonstrate that ENZ metamaterials can induce stable levitation of particles via light-driven forces, offering a novel mechanism for contactless manipulation in microfluidic environments. This work advances understanding of light-matter interactions at ENZ interfaces and suggests potential for ENZ-based optical control of micro- and nanoscale objects, with potential applications in micro- and nanofluidic environments.
|
https://arxiv.org/abs/2601.10425
|
Academic Papers
|
svg
|
634f6330e527b4f26a52d683f66a77ddbc2485f63e67b9ba02ad1dcb80de0812
|
2026-01-16T00:00:00-05:00
|
Active interrogation of underground piezoelectric fabrics using high energy muon beams propagating across seismogenic faults
|
arXiv:2601.10430v1 Announce Type: new Abstract: In this paper we extend a previous analysis of a newly conceived technique based on active interrogation of tectonic stress evolution in regions hosting active seismogenic faults. The aim is to monitor and detect stable and reliable precursor signals on an adequate time scale, well before an earthquake event, that can play a crucial role in activating alarms for civil protection systems. The precursor signal relies on continuous measurements of the time evolution of tectonic stress, obtained by interrogating underground, with a high energy collimated muon beam, the piezoelectric fabrics present in quartz rich granite like rocks surrounding a known seismogenic fault in the Earth crust. Beam propagation through the rock across the active fault conveys to a detector at the exit of the traversal information on the amplitude of the piezoelectric field, which scales with the tectonic stress applied to quartz crystals embedded in the rock. The system, named ERMES (Earthquake Reconnaissance using Muon beam Evolution in Silicon dioxide), differs from other techniques under study detecting electromagnetic signals generated by piezoelectricity outside the Earth crust, as it probes piezoelectric effects directly inside the source region of the associated electromagnetic field, namely the near field within quartz crystals rather than the far field in open space. We present a focused analysis of muon beam manipulation after rock traversal and before detection using a newly conceived muonic lens, and we explore the maximum rock penetration capability of a high energy muon beam, reaching about 3 km of rock thickness for a 10 TeV beam. Owing to the peculiarity of muon propagation through such kilometer scale targets, we cross checked previous FLUKA Monte Carlo simulations with Geant4 to clarify the secondary muons role generated by primary muon interactions in solid matter over long propagation lengths.
|
https://arxiv.org/abs/2601.10430
|
Academic Papers
|
svg
|
0d5b24eef6f1af32b00f5bcdecaff5f305c9bd702f3c73a4c8d726eb210e3800
|
2026-01-16T00:00:00-05:00
|
Submesoscale and boundary layer turbulence under mesoscale forcing in the upper ocean
|
arXiv:2601.10441v1 Announce Type: new Abstract: The interaction among quasi-geostrophic mesoscale eddies, submesoscale fronts, and boundary layer turbulence (BLT) is a central problem in upper ocean dynamics. We investigate these multiscale dynamics using a novel large-eddy simulation on a 100km-scale domain with meter-scale resolution. The simulation resolves BLT energized by uniform surface wind and convective forcing. A front interacts with BLT within a prescribed, spatially inhomogeneous mesoscale eddy field, representing a canonical eddy quadrupole. Using a triple flow decomposition, we analyze the dynamic coupling and kinetic energy budgets among the large-scale field, submesoscale field, and the resolved BLT. Our analysis reveals significant heterogeneity in the structure and intensity of submesoscales and BLT under varying mesoscale forcing. Turbulent kinetic energy and production rates can vary by an order of magnitude along the front, creating distinct turbulent hotspots whose locations are tied to the underlying large-scale flow. The region under stronger mesoscale convergence holds stronger horizontal and vertical geostrophic shear productions for BLT, and stronger self-production and BLT-destruction for submesoscales. In contrast, the region under dominant mesoscale divergence holds dramatic distortion of the front isotherm, along with dominant submesoscale vertical buoyancy production and self-destruction. These results provide a direct characterization of BLT and submesoscales in the ocean mixed layer modulated by a mesoscale eddy field, which can better inform future parameterization developments.
|
https://arxiv.org/abs/2601.10441
|
Academic Papers
|
svg
|
4407d6af9209f96c3c3bf08b143e34fd14a342f5b53e4190640882d17d69d135
|
2026-01-16T00:00:00-05:00
|
From Weibel seeds to collisionless dynamos beyond pair-plasmas
|
arXiv:2601.10472v1 Announce Type: new Abstract: Bridging the spatiotemporal scales of magnetic seed field generation and subsequent dynamo amplification in the weakly collisional intracluster medium presents an extreme numerical challenge. We perform collisionless turbulence simulations with initially unmagnetized electrons that capture both magnetic seed generation via the electron Weibel instability and the ensuing dynamo amplification. Going beyond existing pair-plasma studies, we use an ion-to-electron mass ratio of 100 for which we find electron and ion dynamics are sufficiently decoupled. These simulations are enabled by the 10-moment collisionless fluid solver of Gkeyll, which evolves the full pressure tensor for all species. The electron heat-flux closure regulates pressure isotropization and effectively sets the magnetic Reynolds number. We investigate how the strength of of the closure influences the transition between a regime reminiscent of previous kinetic pair-plasma simulations and a more MHD-like dynamo regime.
|
https://arxiv.org/abs/2601.10472
|
Academic Papers
|
svg
|
9353a17f25138ebf7b3e60ad0637d26fdeee8adbafc6d584ff95782eda0ecef8
|
2026-01-16T00:00:00-05:00
|
Reply to "Comment on Nuclear Fusion 66, 016012 (2026) by Richard Fitzpatrick, A Simple Model of Current Ramp-Up and Ramp-Down in Tokamaks" by A.H. Boozer
|
arXiv:2601.10509v1 Announce Type: new Abstract: This report is a follow up to my paper "A simple model of current ramp-up and ramp-down in tokamaks" [Nucl. Fusion 66, 016012 (2026)] in the light of comments on the paper recently made by Dr. A.H. Boozer (arXiv:2601.05977).
|
https://arxiv.org/abs/2601.10509
|
Academic Papers
|
svg
|
f234c6b53f97757684a7eb039bc4705ca3968d11576d241f6983923ecdbb1949
|
2026-01-16T00:00:00-05:00
|
Nested hyperedges promote the onset of collective transitions but suppress explosive behavior
|
arXiv:2601.10522v1 Announce Type: new Abstract: Higher-order interactions can dramatically reshape collective dynamics, yet how their microscopic organization controls macroscopic critical behavior remains unclear. Here we develop a new theory to study contagion dynamics on hypergraphs and show that nested hyperedges not only facilitate the onset of spreading, but also suppress backward bifurcations, thereby inhibiting explosive behavior. By disentangling contagion pathways, we find that overlap redirects transmission from external links to internal, group-embedded routes -- boosting early activation but making dyadic and triadic channels increasingly redundant. This loss of structural independence quenches the nonlinear amplification required for bistability, progressively smoothing the transition as hyperedges become nested. We observe the same phenomenology in Kuramoto dynamics, pointing to a broadly universal mechanism by which nested higher-order structure governs critical transitions in complex systems.
|
https://arxiv.org/abs/2601.10522
|
Academic Papers
|
svg
|
b5b4292a791f59d6ca99ff61400b7a5bfaeadbe464965e323f94dd5b2610944a
|
2026-01-16T00:00:00-05:00
|
Spatio-spectrally tailored multimode metasurface lasers in the visible range
|
arXiv:2601.10546v1 Announce Type: new Abstract: Spectrally engineered multifrequency nanolasers are highly desirable for on-chip photonics, multiplexed biosensing, and display technologies; yet, achieving them within a single compact platform remains challenging. Here, we demonstrate multimode lasing from symmetry-broken TiO2 metasurfaces integrated with an SU8 slab waveguide containing Rhodamine 6G. By co-engineering guided-mode resonances, surface lattice resonances near Rayleigh anomalies, and quasi-bound states in the continuum, we realize complementary high-Q feedback pathways that overlap with the gain spectrum. The direction of the lasing emission is tailored through outcoupling via second-order Bragg diffraction and Rayleigh anomaly conditions, supporting both normal and oblique emission. Experiments reveal discrete lasing outputs across ~100 nm bandwidth (548-648 nm), spanning nearly the full Rhodamine 6G emission band, with thresholds as low as ~7 nJ per pulse (35.7 uJ/cm^2) and up to four concurrent lasing peaks from a single device. These results establish a metasurface-dye platform for multifrequency and angle-selective lasing, opening new opportunities for compact, multifunctional nanophotonic sources.
|
https://arxiv.org/abs/2601.10546
|
Academic Papers
|
svg
|
102c72509d32b8aed73ac7bddc155d3ad678fb2088bcdd0911e0f273510cd9fb
|
2026-01-16T00:00:00-05:00
|
Canonical Vorticity Perspective on Magnetogenesis: Unifying Weibel, Biermann, and Beyond
|
arXiv:2601.10570v1 Announce Type: new Abstract: We briefly review the current status of magnetogenesis, a cross-disciplinary field that bridges cosmology and plasma physics, studying the origin of magnetic fields in the universe. We formulate a canonical vorticity framework to investigate kinetic plasma physics-based magnetogenesis processes in a collisionless plasma. By considering canonical vorticity, a weighted sum of the fluid vorticity and the magnetic field as the canonical variable, this framework unifies several magnetogenesis processes, including the Biermann battery, the Weibel instability, and predicts several new pressure tensorial configurations as the fundamental source of self-generated magnetic field and vorticity in plasma. The framework is further extended to relativistic regime where an additional source of canonical vorticity, termed as kineclinicity effect, is identified. The theoretical predictions are systematically validated using particle-in-cell simulations, highlighting their implications for laboratory and astrophysical plasma environments.
|
https://arxiv.org/abs/2601.10570
|
Academic Papers
|
svg
|
ac672f1798a64f81f2bf2aa9460af63732d683d25555d839258879d039b71527
|
2026-01-16T00:00:00-05:00
|
Corrections for systematic errors in slit-profiler transverse phase space measurements
|
arXiv:2601.10571v1 Announce Type: new Abstract: In photo injectors, the transverse emittance is one of the key measures of beam quality as it defines the possible performance of the whole facility. As such it is important to measure the emittance in photo injectors and ensure the accuracy of these measurements. While there are many different methods of measuring the emittance, this paper focuses on quantifying the systematic errors present in transverse phase space measurements taken with slit-profiler methods, i.e. scanning a narrow slit over the beam and continually measuring the passed beamlets' divergence with a downstream profiler. The measurement errors include effects of the slit size, beamlet imaging, and residual space charge. While these effects are generally small, they can have significant impact on the measured emittance when the 2D phase space is strongly coupled. The systematic effects studied and corrections are demonstrated with simulations and measurements from the Photo Injector Test facility at DESY in Zeuthen (PITZ) using a slit-screen emittance scanner.
|
https://arxiv.org/abs/2601.10571
|
Academic Papers
|
svg
|
3d13504bea5d601af68cfa5660f727274bce89f1a030b2ef1b92635bbd8efd91
|
2026-01-16T00:00:00-05:00
|
Electro-optic frequency comb Doppler thermometry
|
arXiv:2601.10575v1 Announce Type: new Abstract: We demonstrate a Doppler thermometer based on direct optical frequency comb spectroscopy of an $^{85}$Rb vapor with a chirped electro-optic frequency comb (EOFC). The direct EOFC Doppler thermometer is accurate to within its approximately 1 K statistical uncertainty. We experimentally compare direct EOFC spectroscopy with conventional Doppler spectroscopy using a single-frequency, step-scanned laser probe. Our results show that direct EOFC spectroscopy mitigates transit-induced optical pumping distortion of the atomic lineshape, which is the dominant systematic temperature shift in alkali atom Doppler thermometry. Optical Bloch equation simulations of conventional and direct EOFC Doppler spectroscopy confirm that EOFC spectroscopy can use higher optical power to reduce statistical noise without optical pumping distortion. Our results indicate that EOFC Doppler thermometry is a promising approach to realizing a primary thermometer with size and measurement rate sufficient for applications including pharmaceutical manufacturing and nuclear waste monitoring.
|
https://arxiv.org/abs/2601.10575
|
Academic Papers
|
svg
|
d656b7d113b0f4fdfd427619cf8e1816c91915d550b56da12a8514edc4a3d7a8
|
2026-01-16T00:00:00-05:00
|
On the geometry of aggregate snowflakes
|
arXiv:2601.10608v1 Announce Type: new Abstract: Snowflakes play a crucial role in weather and climate. A significant portion of precipitation that reaches the surface originates as ice, even when it ultimately falls as rain. Contrary to the popular image of symmetric, dendritic crystals, most large snowflakes are irregular aggregates formed through the collision of primary ice crystals, such as hexagonal plates, columns, and dendrites. These aggregates exhibit complex, fractal-like structures, particularly at large sizes. Despite this structural complexity, each aggregate snowflake is unique, with properties that vary significantly around the mean - variability that is typically neglected in weather and climate models. Using a physically based aggregation model, we generate millions of synthetic snowflakes to investigate their geometric properties. The resulting dataset reveals that, for a given monomer number (cluster size) and mass, the maximum dimension follows approximately a lognormal distribution. We present a parameterization of aggregate geometry that captures key statistical properties, including maximum dimension, aspect ratio, cross-sectional area, and their joint correlations. This formulation enables a stochastic representation of aggregate snowflakes in Lagrangian particle models. Incorporating this variability improves the realism of simulated fall velocities, enhances growth rates by aggregation, and broadens Doppler radar spectra in closer agreement with observations.
|
https://arxiv.org/abs/2601.10608
|
Academic Papers
|
svg
|
c96681df7df25e0b5859fb36928104f9d53b29398c18e9a918177091bf72363e
|
2026-01-16T00:00:00-05:00
|
Boundary treatment algorithms for meshfree RANS turbulence modeling
|
arXiv:2601.10661v1 Announce Type: new Abstract: In this paper, we propose improved wall-treatment strategies for meshfree methods applied to turbulent flows. The goal is to improve wall-function handling in simulations of high-Reynolds-number turbulent flows, and to better understand the performance of turbulence models when used with meshfree methods. While wall-function techniques are well established for mesh-based methods, their inclusion in meshfree methods faces unique challenges that have not been fully explored. The main difficulties arise from the lack of connectivity between points and from point movement in Lagrangian frameworks, which can complicate consistent wall treatment. To address these issues, we explore three wall-treatment techniques. We highlight the drawbacks of the standard closest neighbor approach. We then introduce two novel approaches: the nearest-band neighbor method and the shifted boundary method. We evaluate these methods using first-order turbulence closures: Spalart--Allmaras, $k-\varepsilon$, and $k-\omega$. These methods are tested numerically on 1D Couette flow, turbulent flow over a flat plate, and flow around a NACA 0012 airfoil in 3D. The results show that both novel methods outperform the closest neighbor approach. The shifted boundary method achieves higher accuracy, but is more computationally expensive than the nearest-band neighbor method. However, by using smaller shift distances, we can achieve lower $y^+$ values with the same resolution. All turbulence models work well with the shifted boundary method, with only minor differences between them. In contrast, the nearest-band method shows variation in the behavior of the turbulence models, where the Spalart--Allmaras model yields better results, especially further downstream along the plate. This work establishes a robust foundation for simulating wall-bounded turbulent flows at high Reynolds numbers using meshfree collocation methods.
|
https://arxiv.org/abs/2601.10661
|
Academic Papers
|
svg
|
b0b5e5e160213f6ae04745c853444a94e7d3beecbdddb2b995f903f53fabdc22
|
2026-01-16T00:00:00-05:00
|
Optimal universal bounds for waves with varied coherence based on supremum and infimum coherence spectra
|
arXiv:2601.10665v1 Announce Type: new Abstract: We establish a majorization-based theory for bounding observables of waves with varied coherence. For any measurement, exact bounds are attained by the maximal and minimal elements in the set of input coherence spectra. The set's supremum and infimum, which may lie outside the set, provide optimal universal bounds: any alternative spectrum yielding universal bounds produces weaker constraints. We present an algorithm to compute the supremum and infimum, and prove that they lie either at singular boundary points or strictly outside the set of coherence spectra.
|
https://arxiv.org/abs/2601.10665
|
Academic Papers
|
svg
|
81ee5cb49f0425d5692ca1acc5510a285c9a6cb37bfd8d62e3a657c50f07b477
|
2026-01-16T00:00:00-05:00
|
Increasing the opening speed of the plasma opening switch on an direct action accelerator with an inductive energy storage device
|
arXiv:2601.10694v1 Announce Type: new Abstract: To increase the voltage multiplication factor in a small-sized direct-acting electron accelerator DIN-2K with an inductive energy storage and a plasma opening switch, it is necessary to ensure an increase in the rate of change of the current and its amplitude during the POS opening for the purpose of obtaining an explosive electron emission with the formation of an electron beam and a virtual cathode. However, the opening process depends on many electrical parameters of the plant, and it re-quires determining their joint and individual effect on its dynamics. The purpose of this research is to study and determine the effects of electrical parameters, including those of the discharge voltages of the entire electrical circuit of the accelerator on the dynamics of the plasma opening switch, in particular opening speed, current amplitudes, and opening time, as well as to give recommendations on optimizing the operation of accelerators of this type and highlight possible ways to increase the voltage multiplication factor. Methodology. A method for determining the induced voltage according to experimental current oscillograms has been proposed. The methodology was verified by the coincidence of its data with the results of measurements by a capacitive voltage divider with the data spread of less than 20%. Scientific novelty. The rates of change in the current at the plasma switch opening stage were determined depending on the main electrical parameters of the DIN-2K accelerator. The diagnostics of the voltage induced during the POS opening were provided using no capacitive voltage divider in the internal volume of the accelerator, which enabled the removal of some diagnostic tools from the working volume of the chamber. Practical significance.
|
https://arxiv.org/abs/2601.10694
|
Academic Papers
|
svg
|
4fbd5eaf92c2e78d37d617da7e4fc8ba86a479ecad6f267c4225934ed9c31575
|
2026-01-16T00:00:00-05:00
|
Quantum geometry of the rotating shallow water model
|
arXiv:2601.10695v1 Announce Type: new Abstract: The rotating shallow water equations (RSWE) are a mainstay of atmospheric and oceanic modeling, and their wave dynamics has close analogues in settings ranging from two-dimensional electron gases to active-matter fluids. While recent work has emphasized the topological character of RSWE wave bands, here we develop a complementary quantum-geometric description by computing the full quantum geometric tensor (QGT) for the linearized RSWE on an $f$-plane. The QGT unifies two pieces of band geometry: its real part defines a metric that quantifies how rapidly wave polarization changes with parameters, while its imaginary part is the Berry curvature that controls geometric phases and topological invariants. We obtain compact, symmetry-guided expressions for all three bands, highlighting the transverse structure of the metric and the monopole-like Berry curvature that yields Chern numbers for the Poincar\'e bands. Finally, we describe a feasible route to probing this geometry in rotating-tank experiments via weak, time-periodic parametric driving.
|
https://arxiv.org/abs/2601.10695
|
Academic Papers
|
svg
|
625acfe4b3ffeb92ae3410055664d192403004240e874a5c33541431a42f54d5
|
2026-01-16T00:00:00-05:00
|
Entropic Approach to Critical Materials Assessment
|
arXiv:2601.09827v1 Announce Type: cross Abstract: Most methodologies for materials criticality assessment score supply risk and societal importance. Market-based criteria offer quantitative measures for assessment. Here we develop a statistical approach based on a geologic entropy function in which flexible constraints, such as economic, national security related, or regulatory, can be applied. As an example, the formulation describes the relation between elemental price and crustal abundance for selected elements, both important to supply risk. The method may be applicable to parameters resulting from collective decisions exhibiting a highly peaked probability distribution.
|
https://arxiv.org/abs/2601.09827
|
Academic Papers
|
svg
|
0978fd2df8b3db55d1df0e16fa022a2bcdd8aa70e343c36d1e060f02aa397829
|
2026-01-16T00:00:00-05:00
|
Multi-level quantum emitter in an optical waveguide: paradoxes and resolutions
|
arXiv:2601.09854v1 Announce Type: cross Abstract: We theoretically investigate the optical dipole interaction between a multi-level quantum system and a single-mode optical waveguide of any local polarisation. We investigate several paradoxical seeming situations, for example we find a situation in which there exist two non-orthogonal quantum states, each of which results in a photon flux in the opposite direction to the other. We show how, despite appearances, this does not break the unitary requirements of quantum mechanics. We also find that an isotropic quantum emitter can be either reflective or transmissive to light depending on the waveguide polarisation at the emitter location, indeed in the zero loss limit such a system changes from 100% transmission to 100% reflection due to an infinitesimal polarisation rotation. An example case for a four level system is also considered, which is found to operate as a non-destructive parity measurement of the photon number.
|
https://arxiv.org/abs/2601.09854
|
Academic Papers
|
svg
|
a4ff997d7ae90ab307409e6e59d40956a6d90fffb4da100038afa1dc180cacc8
|
2026-01-16T00:00:00-05:00
|
Statistical-noise-enhanced multi-photon interference
|
arXiv:2601.09977v1 Announce Type: cross Abstract: Photon statistics plays a governing role in multi-photon interference. While interference visibility in the standard two-photon case, known as Hong-Ou-Mandel interference, monotonically degrades with higher intensity correlation functions, we show that this monotonicity does not hold for three-photon interference in symmetric circuits. We reveal that, in the discrete Fourier transform circuit, engineered super-Poissonian photon-number fluctuations, realized using a modulated laser, maximize the visibility, surpassing the magnitude of the single-photon signature. In addition, by tuning the symmetric circuit parameters, we demonstrate that the visibility hierarchy inverts relative to the benchmark of Poissonian statistics. This trade-off implies that quantum and classical advantages are mutually exclusive resources for interference, indicating a form of statistical complementarity.
|
https://arxiv.org/abs/2601.09977
|
Academic Papers
|
svg
|
8f7855e94fdc2d1d21b609784dfba13ee87983b4675ff17d2bbf25e2adc4ef01
|
2026-01-16T00:00:00-05:00
|
Electronic structure theory of H$_{3}$S: Plane-wave-like valence states, density-of-states peak and its guaranteed proximity to the Fermi level
|
arXiv:2601.10016v1 Announce Type: cross Abstract: Superconductivity in sulfur superhydride H$_{3}$S under extreme pressures has been explained theoretically, but it requires a peaked concentration of the electronic density of states (DOS), which has been found in first-principles calculations. The mechanism of this peak formation, though vital for its high transition temperature, has however remained obscure. We address this problem through detailed analysis of the first-principles electronic wave functions. The valence wave functions are shown to be significantly plane-wave-like. From the Fourier-mode analysis of the self-consistent potential and atomic pseudopotentials, we extract the nearly uniform models that accurately reproduce the first-principles band structure with very few parameters. The DOS peak is shown to be the consequence of the hybridization of specific plane waves. Adjacency of Jones' large zone to the plane-wave spherical Fermi surface is posited to be the root cause of the multiple plane-wave hybridization, the DOS peak formation and its proximity to the Fermi level. The present theory resolves the minimal modeling problem of electronic states in H$_{3}$S, as well as establishes a mechanism that may help to boost the transition temperatures in pressure induced superconductors.
|
https://arxiv.org/abs/2601.10016
|
Academic Papers
|
svg
|
dbdaf2fcdddca87c0f67ebab908c01c332ddffae5327e963bfb14effa2936d12
|
2026-01-16T00:00:00-05:00
|
Rotational Memory Function of SPC/E water
|
arXiv:2601.10022v1 Announce Type: cross Abstract: Memory effects are essential for dynamics of condensed materials and are responsible for non-exponential relaxation of correlation functions of dynamic variables through the memory function. Memory functions of dipole rotations for polar liquids have never been calculated. We present here calculations of memory functions for single-dipole rotations and for the overall dipole moment of the sample for SPC/E water. The memory functions for single-particle and collective dipole dynamics turn out to be nearly identical. This result validates theories of dielectric spectroscopy in terms of single-particle time correlation functions and the connection between the collective and single-particle relaxation times through the Kirkwood factor. The dielectric function in this formalism contains no new dynamic information that does not exist in the single-dipole correlation function. A short memory time, $\lesssim 1$ fs, justifies the use of rotational diffusion model to describe dynamics of a single molecular dipole moment in bulk water.
|
https://arxiv.org/abs/2601.10022
|
Academic Papers
|
svg
|
67ec07fb30e58ba0ab27cf36aaf9ec643a2802f215aecdbd6865f708abbb9ab1
|
2026-01-16T00:00:00-05:00
|
Geometric Criteria for Complete Mode Conversion in Detuned Systems via Piecewise-Coherent Modulation
|
arXiv:2601.10066v1 Announce Type: cross Abstract: Static phase detuning fundamentally constrains coherent state transfer in asymmetric classical and quantum systems. We introduce a Bloch-sphere formulation for piecewise-coherent modulation that recasts coupled-mode dynamics as geometric trajectories, transforming algebraic control into path optimization. The approach reveals a cone of inaccessibility at the target pole and yields exact geodesic criteria for complete mode conversion in detuned systems. Leveraging this framework, we break time-reversal symmetry to realize a magnet-free optical isolator with near-unity contrast. Furthermore, for detuning larger than coupling between modes, we develop a recursive multi-step protocol enabling deterministic transfer for arbitrary detunings and derive a universal geometric lower bound on the required number of coupling-switching events.
|
https://arxiv.org/abs/2601.10066
|
Academic Papers
|
svg
|
42d07639343e6827934f367d75501b978da59a6e141b725e3f555f25757921b4
|
2026-01-16T00:00:00-05:00
|
Casimir interactions as a probe of broadband optical response
|
arXiv:2601.10118v1 Announce Type: cross Abstract: Casimir forces arise from quantum electromagnetic fluctuations and depend on the dielectric response of interacting materials across the entire frequency spectrum. Although this dependence is central to Lifshitz theory of the Casimir effect, the formulation of the force in terms of dielectric functions evaluated at imaginary frequencies has largely obscured its connection to real-frequency optical properties, limiting the use of Casimir interactions as a probe of materials. Here we demonstrate that Casimir force measurements encode sufficient information to reconstruct a material's broadband optical response. Using supervised machine learning to invert Lifshitz theory, we determine the complex permittivity of a material over more than seven orders of magnitude in frequency from a single force-distance curve. We show that measurements at different separations selectively constrain distinct frequency ranges of the dielectric response, providing direct physical insight into how quantum fluctuations sample the electromagnetic spectrum. These results establish Casimir interactions as a physically constrained, broadband spectroscopic tool and open new opportunities for optical characterization in regimes inaccessible to conventional techniques.
|
https://arxiv.org/abs/2601.10118
|
Academic Papers
|
svg
|
3f80b149da042e78ecc885046d80c9129d0c923ae44f82b42eaad5fa054bf842
|
2026-01-16T00:00:00-05:00
|
Computing Statistical Properties of Velocity Fields on Current Quantum Hardware
|
arXiv:2601.10166v1 Announce Type: cross Abstract: Quantum algorithms are gaining attention in Computational Fluid Dynamics (CFD) for their favorable scaling, as encoding physical fields into quantum probability amplitudes enables representation of two to the power of n spatial points with only n qubits. A key challenge in Quantum CFD is the efficient readout of simulation results, a topic that has received limited attention in literature. This work presents methods to extract statistical properties of spatial velocity fields, such as central moments and structure functions, directly from parameterized ansatz circuits, avoiding full quantum state tomography. As a proof of concept, we implement our approach for 1D velocity fields, encoding 16 spatial points with 4 qubits, and analyze both a sine wave signal and four snapshots from Burgers' equation evolution. Using Qedma's error mitigation software QESEM, we demonstrate that such computations achieve high accuracy on current quantum devices, specifically IBMQ's Heron2 system ibm_fez.
|
https://arxiv.org/abs/2601.10166
|
Academic Papers
|
svg
|
2c06ca308029d93b38caa23915ee9f592686d5af70adbbcb662dc07ec15279b5
|
2026-01-16T00:00:00-05:00
|
Autonomous Quantum Simulation through Large Language Model Agents
|
arXiv:2601.10194v1 Announce Type: cross Abstract: We demonstrate that large language model (LLM) agents can autonomously perform tensor network simulations of quantum many-body systems, achieving approximately 90% success rate across representative benchmark tasks. Tensor network methods are powerful tools for quantum simulation, but their effective use requires expertise typically acquired through years of graduate training. By combining in-context learning with curated documentation and multi-agent decomposition, we create autonomous AI agents that can be trained in specialized computational domains within minutes. We benchmark three configurations (baseline, single-agent with in-context learning, and multi-agent with in-context learning) on problems spanning quantum phase transitions, open quantum system dynamics, and photochemical reactions. Systematic evaluation using DeepSeek-V3.2, Gemini 2.5 Pro, and Claude Opus 4.5 demonstrates that both in-context learning and multi-agent architecture are essential. Analysis of failure modes reveals characteristic patterns across models, with the multi-agent configuration substantially reducing implementation errors and hallucinations compared to simpler architectures.
|
https://arxiv.org/abs/2601.10194
|
Academic Papers
|
svg
|
59cfb0541759344ad145f48b970086f10bcbf2c8c1d6b6cd9f3f2ee2ae5a70a8
|
2026-01-16T00:00:00-05:00
|
Physically Unclonable Functions Based on Single-Walled Carbon Nanotubes: A Scalable and Inexpensive Method toward Unique Identifiers
|
arXiv:2601.10196v1 Announce Type: cross Abstract: A physically un-clonable function (PUF) is a physical system that cannot be reproduced or predicted and therefore is a good basis to build security and anti-counterfeiting applications. The unclonability of PUFs typically stems from the randmoness induced in a system during sophisticated fabrication methods. It is precisely this built-in complexity the bottleneck hindering scalability and increasing costs. Here, we produce in a simple manner PUFs based on arrays of carbon nanotubes junctions simultaneously assembled by dielectrophoresis. We demonstrate that the intrinsic inhomogeneity of carbon nanotubes at the nanoscale, combined with the unpredictability introduced by liquid phase-based fabrication methods results in unique electronic profiles of easily scalable devices. This approach could be extrapolated to generate PUFs based on other nanoscale materials
|
https://arxiv.org/abs/2601.10196
|
Academic Papers
|
svg
|
8273360029b6ddc304ff89bd94a0ba3baeec3723ab311db2e89df009a0d0731c
|
2026-01-16T00:00:00-05:00
|
The hidden structure of innovation networks
|
arXiv:2601.10224v1 Announce Type: cross Abstract: Innovation emerges from complex collaboration patterns - among inventors, firms, or institutions. However, not much is known about the overall mesoscopic structure around which inventive activity self-organizes. Here, we tackle this problem by employing patent data to analyze both individual (\emph{co-inventorship}) and organization (\emph{co-ownership}) networks in three strategic domains (\emph{artificial intelligence}, \emph{biotechnology} and \emph{semiconductors}). We characterize the mesoscale structure (in terms of clusters) of each domain by comparing two alternative methods: a standard baseline - modularity maximization - and one based on the minimization of the Bayesian Information Criterion, within the Stochastic Block Model and its degree-corrected variant. We find that, across sectors, inventor networks are denser and more clustered than organization ones - consistent with the presence of small recurrent teams embedded into broader institutional hierarchies - whereas organization networks have neater hierarchical role-based structures, with few bridging firms coordinating the most peripheral ones. We also find that the discovered meso-structures are connected to innovation output. In particular, Lorenz curves of forward citations show a pervasive inequality in technological influence: across sectors and methods, both inventor (especially) and organization networks consistently show high levels of concentration of citations in a few of the discovered clusters. Our results demonstrate that the baseline modularity-based method may not be capable of fully capturing the way collaborations drive the spreading of inventive impact across technological domains. This is due to the presence of local hierarchies that call for more refined tools based on Bayesian inference.
|
https://arxiv.org/abs/2601.10224
|
Academic Papers
|
svg
|
ff7b820274c419c00037e6d63cc032bcd0393e7a727e5fca84565d438cc610e1
|
2026-01-16T00:00:00-05:00
|
Enhanced multi-parameter metrology in dissipative Rydberg atom time crystals
|
arXiv:2601.10347v1 Announce Type: cross Abstract: The pursuit of unprecedented sensitivity in quantum enhanced metrology has spurred interest in non-equilibrium quantum phases of matter and their symmetry breaking. In particular, criticality-enhanced metrology through time-translation symmetry breaking in many-body systems, a distinct paradigm compared to spatial symmetry breaking, is a field still in its infancy. Here, we have investigated the enhanced sensing at the boundary of a continuous time-crystal (CTC) phase in a driven Rydberg atomic gas. By mapping the full phase diagram, we identify the parameter-dependent phase boundary where the time-translation symmetry is broken. This allows us to use a single setup for measuring multiple parameters, in particular frequency and amplitude of a microwave field. By increasing the microwave field amplitude, we first observe a phase transition from a thermal phase to a CTC phase, followed by a second transition into a distinct CTC state, characterized by a different oscillation frequency. Furthermore, we reveal the precise relationship between the CTC phase boundary and the scanning rate, displaying enhanced precision beyond the Standard Quantum Limit. This work not only provides a promising paradigm rooted in the critical properties of time crystals, but also advances a method for multi-parameter sensing in non-equilibrium quantum phases.
|
https://arxiv.org/abs/2601.10347
|
Academic Papers
|
svg
|
00a7166ecaa570a9969b4f79209f584700656cc52119f3a179ad8c49792cb451
|
2026-01-16T00:00:00-05:00
|
Capillary Slinky: Equilibrium and Dynamics of Droplets in a Soft Spring
|
arXiv:2601.10366v1 Announce Type: cross Abstract: Springs can be found in many applications and biological systems, and when these are soft, they easily deform. At small scales, capillarity can induce a force leading to spring deformations when the elastocapillary number is small. We demonstrate through experiments the non-trivial equilibrium shape liquid droplets adopt in these soft springs, which form an annulus, Eruciform, and spherical shapes. When these droplets are set in motion, they display different flow regimes with significant dissipation generated by the internal rotational flow. The static and dynamics of droplets in such a capillary slinky is also used to demonstrate how surface tension can actuate springs by stretching/compression, while providing a way for active flow control in soft springs.
|
https://arxiv.org/abs/2601.10366
|
Academic Papers
|
svg
|
db5db4730ef3ab944a24a59639871585c051de19f7a2195da36293f06f2b508d
|
2026-01-16T00:00:00-05:00
|
A comparison of simulation tools for Muon-Induced X-ray Emission (MIXE) in thin films: a study case with lithium batteries
|
arXiv:2601.10401v1 Announce Type: cross Abstract: We present a comparative study of three Monte Carlo simulation frameworks -SRIM, GEANT4, and PHITS- for modeling the transport, stopping, and atomic cascade of negative muons in micrometer-scale, multilayer systems relevant to Muon-Induced X-ray Emission (MIXE) experiments at the Paul Scherrer Institute (PSI). Using a lithium-ion battery as a benchmark target, simulated implantation profiles are compared with experimental data from the GIANT spectrometer. All three codes reproduce the overall muon depth distributions with good consistency, even across sharp density contrasts. SRIM provides reliable implantation estimates for compact geometries, whereas PHITS reproduces GEANT4 results with comparable accuracy and additionally generates muonic X-ray spectra. These spectra, however, exhibit a systematic energy offset in the K-line transitions of medium- and high-Z elements relative to theoretical and experimental values. Despite this bias, PHITS accurately captures relative intensities and spectral shapes, enabling element-specific line identification. The results demonstrate that SRIM and PHITS constitute practical tools for rapid estimation of muon implantation and stopping profiles, and that PHITS holds strong potential for predictive MIXE spectroscopy once its transition-energy bias is corrected.
|
https://arxiv.org/abs/2601.10401
|
Academic Papers
|
svg
|
f46c479a49c0ab7f6de7d764b399c370c1babaa457967a92a3882aeba377b09f
|
2026-01-16T00:00:00-05:00
|
Cloud parameter estimation for interacting BEC after time-of-flight
|
arXiv:2601.10415v1 Announce Type: cross Abstract: Experiments on Bose-Einstein condensates at finite temperature typically extract the system parameters, such as temperature, atom number, and condensed fraction from time-of-flight images taken after a free expansion time. This paper systematically examines the effect of repulsive interactions between the condensed and thermal atoms in partially condensed clouds on the expansion profile of the thermal cloud. An analytical expression for the expansion can be obtained only if the interactions between the Bose-Einstein condensate and thermal atoms are neglected, resulting in a Bose-enhanced distribution for the thermal component. Here, the deformation of the cloud due to interactions and the effects on estimated parameters are investigated by simulating the expansion using a ballistic approximation. By fitting the simulated expansion profiles with a Bose-enhanced distribution, the errors of using such a fit are estimated, and the results are explained phenomenologically. The simulation was also used as a fitting function for experimental data, showing better agreement of the extracted condensed fraction with the semi-ideal model than results from a Bose-enhanced fit.
|
https://arxiv.org/abs/2601.10415
|
Academic Papers
|
svg
|
1ff39962173b4990d4bd2c5bb4de4f7becb032c5283d44525b78242a916e2c96
|
2026-01-16T00:00:00-05:00
|
The transformation mechanisms among cuboctahedra, Ino's decahedra and icosahedra structures of magic-size gold nanoclusters
|
arXiv:2601.10434v1 Announce Type: cross Abstract: Gold nanoclusters possess multiple competing structural motifs with small energy differences, enabling structural coexistence and interconversion. Using a high-accuracy machine learned potential trained on some 20'000 density functional theory reference data points, we investigate transformation pathways connecting both high-symmetry and amorphous cuboctahedra, Ino's decahedra and icosahedra for Au55, Au147, Au309 and Au561 nanoclusters. Our saddle point searches reveal that high-symmetry transformations from cuboctahedra and Ino's decahedra to icosahedra proceed through a single barrier and represent soft-mode-driven jitterbug-type and slip-dislocation motions. In addition, we identify lower-barrier asymmetric transformation pathways that drive the system into disordered, Jahn-Teller-stabilized amorphous icosahedra. Minima Hopping sampling further uncovers, in this context, many such low-symmetry minima. Some of the newly identified global minima for Au309 and Au561 have energies that are up to 2.8 eV lower than the previously reported global minima. Hence, both the shapes and the transformation pathways studied in previous investigations are not the physically relevant ones. In contrast to the previously studied pathways, our transformation pathways give reasonable transformation times that are in rough agreement with experiments.
|
https://arxiv.org/abs/2601.10434
|
Academic Papers
|
svg
|
6f6a9cd6ec4e6b1fe151e8f869ddc93f9d09cf994c650ad2dbc40a3e02a7f61f
|
2026-01-16T00:00:00-05:00
|
Comprehensive parameter and electrochemical dataset for a 1 Ah graphite/LNMO battery cell for physical modelling as a blueprint for data reporting in battery research
|
arXiv:2601.10507v1 Announce Type: cross Abstract: While current technology has enabled their widespread use, further improvements are needed for stationary, portable, and mobile applications, for example by the development of novel cathode materials. Digitalization of battery development, combining both experimental and modelling efforts is extremely valuable in this development. This is addressed in the present paper, where the authors present a comprehensive dataset for a graphite/LNMO 1 Ah pouch cell, including material, design, and electrochemical data. The dataset, validated through the BattMo modelling framework, supports physical modelling and aims to benefit the battery modelling community by offering a comprehensive resource for future studies. Both the dataset and the accompanying software for numerical validation is openly available and processed in such a way that it can serve as blueprint for reporting of comparable research data.
|
https://arxiv.org/abs/2601.10507
|
Academic Papers
|
svg
|
61ece817e7a6307ad174f476bf7ea38a30970ab2c3f3ac43a7cc5c8c54b5a099
|
2026-01-16T00:00:00-05:00
|
Counterdiabatic driving for random-gap Landau-Zener transitions
|
arXiv:2601.10659v1 Announce Type: cross Abstract: The Landau--Zener (LZ) model describes a two-level quantum system that undergoes an avoided crossing. In the adiabatic limit, the transition probability vanishes. An auxiliary control field $H_\text{CD}$ can be reverse-engineered so that the full Hamiltonian $H_0 + H_\text{CD}$ reproduces adiabaticity for all parameter values. Our aim is to construct a single control field $H_1$ that drives an ensemble of LZ-type Hamiltonians with a distribution of energy gaps. $H_1$ works best statistically, minimizing the average transition probability. We restrict our attention to a special class of $H_1$ controls, motivated by $H_\text{CD}$. We found a systematic trade-off between instantaneous adiabaticity and the final transition probability. Certain limiting cases with a linear sweep can be treated analytically; one of them being the LZ system with Dirac $\delta(t)$ function. Comprehensive and systematic numerical simulations support and extend the analytic results.
|
https://arxiv.org/abs/2601.10659
|
Academic Papers
|
svg
|
a361a2f8e52f305408d5ab6e4cbdce741f842b2e985c234acb4e1c82c3929a61
|
2026-01-16T00:00:00-05:00
|
Mitigating nonlinear transduction noise in high-cooperativity cavity optomechanics
|
arXiv:2601.10689v1 Announce Type: cross Abstract: Coupling mechanical motion to an optical resonator enables displacement measurements approaching the standard quantum limit (SQL). However, increasing the optomechanical coupling strength will inevitably lead to probing of the nonlinear response of the optical resonator. Thermal intermodulation noise (TIN) arising from the nonlinear mixing of thermomechanical motion can further increase the imprecision well above the SQL and has hitherto been canceled up to second order of nonlinearity via operation at the "magic detuning". In this work, we record the output of a membrane-in-the-middle microcavity system operating at room temperature and achieving high cooperativity, $C>n_\text{th}$, and apply a nonlinear transform that removes all orders of TIN, improving the mechanical signal-to-noise ratio by nearly 10 dB. Our results can be applied to experiments affected by third-order TIN, which we expect to be the dominating intrinsic source of noise in high-cooperativity room-temperature cavity optomechanical systems.
|
https://arxiv.org/abs/2601.10689
|
Academic Papers
|
svg
|
22e303b05c9bbee8f928c58fcac49cc525920e24723fd20b32f1bd6dc67822d6
|
2026-01-16T00:00:00-05:00
|
Asymmetric Electrostatic Dodecapole: Compact Bandpass Filter with Low Aberrations for Momentum Microscopy
|
arXiv:2303.18100v2 Announce Type: replace Abstract: Imaging energy filters in photoelectron microscopes and momentum microscopes use spherical fields with deflection angles of 90{\deg}, 180{\deg}, and even 2 x 180{\deg}. These instruments are optimized for high energy resolution, but exhibit image aberrations when operated in high transmission mode at medium energy resolution. Here we present a new approach for bandpass-filtered imaging in real or reciprocal space using an electrostatic dodecapole with an asymmetric electrode array. In addition to energy-dispersive beam deflection, this multipole allows aberration correction up to the 3rd order. Here we describe its use as a bandpass prefilter in a time-of-flight momentum microscope at the hard X-ray beamline P22 of PETRA III. The entire instrument is housed in a straight vacuum tube because the deflection angle is only 4{\deg} and the beam displacement in the filter is only 8 mm. The multipole is framed by transfer lenses in the entrance and exit branches. Two sets of 16 different sized entrance and exit apertures on piezomotor driven mounts allow selection of the desired bandpass. For pass energies between 100 and 1400 eV and slit widths between 0.5 and 4 mm the transmitted kinetic energy intervals are between 10 eV and a few hundred eV (FWHM). The filter eliminates all higher or lower energy signals outside the selected bandpass, significantly improving the signal-to-background ratio in the ToF analyzer.
|
https://arxiv.org/abs/2303.18100
|
Academic Papers
|
svg
|
c51c341d03d2fdd1868fa96a87d2fb33c4ccf73d96cba38f69fab3244bad5e9c
|
2026-01-16T00:00:00-05:00
|
Collisional whistler instability and electron temperature staircase in inhomogeneous plasma
|
arXiv:2406.10979v2 Announce Type: replace Abstract: High-beta magnetized plasmas often exhibit anomalously structured temperature profiles, as seen from galaxy cluster observations and recent experiments. It is well known that when such plasmas are collisionless, temperature gradients along the magnetic field can excite whistler waves that efficiently scatter electrons to limit their heat transport. Only recently has it been shown that parallel temperature gradients can excite whistler waves also in collisional plasmas. Here we develop a Wigner--Moyal theory for the collisional whistler instability starting from Braginskii-like fluid equations in a slab geometry. This formalism is necessary because, for a large region in parameter space, the fastest-growing whistler waves have wavelengths comparable to the background temperature gradients. We find additional damping terms in the expression for the instability growth rate involving inhomogeneous Nernst advection and resistivity. They (i) enable whistler waves to re-arrange the electron temperature profile via growth, propagation, and subsequent dissipation, and (ii) allow non-constant temperature profiles to exist stably. For high-beta plasmas, the marginally stable solutions take the form of a temperature staircase along the magnetic field lines. The electron heat flux can also be suppressed by the Ettingshausen effect when the whistler intensity profile is sufficiently peaked and oriented opposite the background temperature gradient. This mechanism allows cold fronts without magnetic draping, might reduce parallel heat losses in inertial fusion experiments, and generally demonstrates that whistler waves can regulate transport even in the collisional limit.
|
https://arxiv.org/abs/2406.10979
|
Academic Papers
|
svg
|
d73270a11ce69a25ed05ded683f3bc299abd89e7c6958719553a9c7e90be3c1c
|
2026-01-16T00:00:00-05:00
|
Long-range optomechanical interactions in SiN membrane arrays
|
arXiv:2408.03066v2 Announce Type: replace Abstract: Optomechanical systems using a membrane-in-the-middle configuration can exhibit a long-range type of interaction similar to how atoms show collective motion in an optical potential. Photons bounce back and forth inside a high-finesse Fabry-P\'{e}rot cavity and mediate the interaction between multiple membranes over a significant distance compared to the wavelength. Recently, it has been demonstrated that off-resonant coupling between light and the inter-membrane cavity can lead to coherent mechanical noise cancellation. On-resonance coupling of light with both the Fabry-P\'{e}rot and inter-membrane cavities, predicted to enhance the single photon optomechanical coupling, have to date not been experimentally demonstrated, however. In our experiment, a double-membrane system inside a Fabry-P\'{e}rot cavity resonantly enhances the cavity field, resulting in a stronger optomechanical coupling strength from the increased radiation pressure. The resonance condition is first identified by analyzing the slope of the dispersion relation. Then, the optomechanical coupling is determined at various chip positions over one wavelength range. The optimum coupling conditions are obtained and enhancement is demonstrated for double membrane arrays with three different reflectivites, reaching nearly four-fold enhancement for the collective motion of $R=65\%$ double membranes. The cavity losses at the optimum coupling are also characterized and the potential of reaching the single-photon strong coupling regime is discussed.
|
https://arxiv.org/abs/2408.03066
|
Academic Papers
|
svg
|
15f5ff8b2a1eeafa95a2f37c3afb9d61b6fb6c0c2580e55d8232bf70e418443b
|
2026-01-16T00:00:00-05:00
|
Fast physics-based launcher optimization for electron cyclotron current drive
|
arXiv:2501.04619v2 Announce Type: replace Abstract: With the increased urgency to design fusion pilot plants, fast optimization of electron cyclotron current drive (ECCD) launchers is paramount. Traditionally, this is done by coarsely sampling the 4-D parameter space of possible launch conditions consisting of (1) the launch location (constrained to lie along the reactor vessel), (2) the launch frequency, (3) the toroidal launch angle, and (4) the poloidal launch angle. For each initial condition, a ray-tracing simulation is performed to evaluate the ECCD efficiency. Unfortunately, this approach often requires a large number of simulations (sometimes millions in extreme cases) to build up a dataset that adequately covers the plasma volume, which must then be repeated every time the design point changes. Here we adopt a different approach. Rather than launching rays from the plasma periphery and hoping for the best, we instead directly reconstruct the optimal ray for driving current at a given flux surface using a reduced physics model coupled with a commercial ray-tracing code. Repeating this throughout the plasma volume requires only hundreds of simulations, constituting a significant speedup. The new method is validated on two separate example tokamak profiles, and is shown to reliably drive localized current at the specified flux surface with the same optimal efficiency as obtained from the traditional approach.
|
https://arxiv.org/abs/2501.04619
|
Academic Papers
|
svg
|
56d65d0a4d35d8031edf96acb7387649b37f2655c88f6a9fe394fc3ccdcda0b9
|
2026-01-16T00:00:00-05:00
|
Chemistry in a Cryogenic Buffer Gas Cell
|
arXiv:2501.05613v2 Announce Type: replace Abstract: Cryogenic buffer gas sources are ubiquitous for producing cold, collimated molecular beams for quantum science, chemistry, and precision measurements. The molecules are typically produced by laser ablating a metal target in the presence of a donor gas. The radical of interest emerges due to a barrier-free reaction or under thermal or optical excitation. High-barrier reactions, such as between Ca and H$_2$, should be precluded. We study chemical reactions between Ca and three hydrogen isotopologues H$_2$, D$_2$, and HD in a cryogenic cell with helium buffer gas. We observe that H$_2$ can serve as both a reactant and a buffer gas, outperforming D$_2$ and HD. We use a reaction network model to describe the chemical dynamics and find that the enhanced molecular yield can be attributed to rapid vibrational excitations of the reactant gas. Our results demonstrate a robust method for generating bright cold beams of alkaline-earth-metal hydrides for laser cooling and trapping.
|
https://arxiv.org/abs/2501.05613
|
Academic Papers
|
svg
|
7d5134ae9c15dd0fb0f3144763845b6ba799a9e245420b8a53d1a35d03abc5d9
|
2026-01-16T00:00:00-05:00
|
Laser-induced plasma formation and cavitation in water: from nanoeffects to extreme states of matter
|
arXiv:2501.11029v2 Announce Type: replace Abstract: We present an in-depth analysis of the energy dependence of optical breakdown in water by tightly focused laser pulses, from plasma formation to shock waves and cavitation. Laser pulses of fs to ns durations and UV to IR wavelengths are aberration-free focused through microscope objectives. Photography captures luminescent plasmas with submicrometer resolution, and bubble threshold and size are determined via probe beam scattering. The energy dependence of mechanical effects is quantified through the maximum bubble radius Rmax. We find three key scenarios depicting the interaction between multiphoton and avalanche ionization, recombination, and thermal ionization from nanoeffects near threshold to extreme energy densities. They include a previously unknown scenario that emerges with single-longitudinal-mode UV ns pulses from compact lasers. It enables cost-effective creation of nanoeffects, as demonstrated on corneal tissue and glass. High-resolution photography reveals new insights in the spatiotemporal dynamics of plasma formation, with an interplay of breakdown waves, string formation by local instabilities of avalanche ionization, and radiative energy transport. Plasma volume data from photographs together with absorption measurements show that the average energy density of luminescent fs and ns plasmas is similar, ranging between 10 and 40 kJ/cm^3 . However, small hot regions with up to 400 kJ/cm^3 are formed in ns breakdown. From the hot regions, energy is spread out via X-ray bremsstrahlung, forming a luminescent halo. Well above threshold, Rmax scales with E^(1/3) across all scenarios, with 15% - 20% conversion of laser energy into bubble energy. With increasing plasma energy density, an ever-larger energy fraction is converted into shock wave energy (75% at 40 kJ/cm^3 ). The results provide guidelines for parameter selection in laser surgery and material processing.
|
https://arxiv.org/abs/2501.11029
|
Academic Papers
|
svg
|
7c23ed2ba8ed9e1c756aefcb9a2002572a6c9595b0b8d8675892cd5c0d6268f2
|
2026-01-16T00:00:00-05:00
|
Stationary multiple euclidon solutions to the vacuum Einstein equations
|
arXiv:2502.03675v3 Announce Type: replace Abstract: The non-linear superposition of the stationary euclidon solution with an arbitrary axially symmetric stationary gravitational field on the basis of the method of variation of parameters was constructed. Stationary soliton solution of the Einstein equations was generalized to the case of a stationary seed metric. The formulae obtained have a simple and compact form, permitting an effective non-linear "addition" of the solutions. These euclidon solutions serve as building block of the theory, which allows for the construction of almost all known solutions to the vacuum static axially-symmetric Einstein equations, including such important ones as the Kerr-NUT solution. The stationary euclidon solution has a clear physical interpretation as a relativistic accelerated non-inertial reference frame, which provides a different perspective on the physical interpretation of well-known solutions, such as the Kerr solution.
|
https://arxiv.org/abs/2502.03675
|
Academic Papers
|
svg
|
9c4a3eaca4a253d5c134b2335329727ad41a8db396cd9b5adc105731b3647ff9
|
2026-01-16T00:00:00-05:00
|
Reversible grain boundary complexion transition explains cratonic lithosphere anomalies
|
arXiv:2504.19784v2 Announce Type: replace Abstract: Olivine comprises approximately 70 $\%$ by volume of the Earth's upper mantle, making it likely that it controls the mechanical, electrical and seismic properties of the upper mantle. All rocks are composed of crystals separated by grain boundaries, which affect their overall conductivity, strength and viscosity. Here, we present a study of forsterite (Mg$_{2}$SiO$_{4}$) polycrystals synthesised between 1150 $^{\circ}$C and 1390 $^{\circ}$C to obtain samples with different grain sizes. The grain boundary plane distributions (GBPD) were analysed by SEM and EBSD. A reversible change in the GBPD is observed between 1290 $^{\circ}$C and 1390 $^{\circ}$C. The GBPD shows that the most commonly occurring grain boundary planes are {0kl}-type at 1290 $^{\circ}$C and below, while at 1390 $^{\circ}$C, (010) grain boundary planes dominate the average crystal habitus. The least common planes at all temperatures are (100). This reversible transition in the dominant grain boundary plane type is evidence for a temperature-dependent complexion transition occurring between 1290 $^{\circ}$C and 1390 $^{\circ}$C. It is well established that different grain boundary crystallographies are related to different grain boundary properties. We relate the observed grain boundary complexion transition to differences in grain boundary properties observed in previous studies and suggest their influence on bulk rock properties.
|
https://arxiv.org/abs/2504.19784
|
Academic Papers
|
svg
|
944e3a14895e338c4cb06f6d3d84110b0a7e11bcdfacb9e3cc909194194ba168
|
2026-01-16T00:00:00-05:00
|
$\mathcal{H}$-HIGNN: A Scalable Graph Neural Network Framework with Hierarchical Matrix Acceleration for Simulation of Large-Scale Particulate Suspensions
|
arXiv:2505.08174v3 Announce Type: replace Abstract: We present a fast and scalable framework, leveraging graph neural networks (GNNs) and hierarchical matrix ($\mathcal{H}$-matrix) techniques, for simulating large-scale particulate suspensions, which have broader impacts across science and engineering. The framework draws on the Hydrodynamic Interaction Graph Neural Network (HIGNN) that employs GNNs to model the mobility tensor governing particle motion under hydrodynamic interactions (HIs) and external forces. HIGNN offers several advantages: it effectively captures both short- and long-range HIs and their many-body nature; it realizes a substantial speedup over traditional methodologies, by requiring only a forward pass through its neural networks at each time step; it provides explainability beyond black-box neural network models, through direct correspondence between graph connectivity and physical interactions; and it demonstrates transferability across different systems, irrespective of particles' number, concentration, configuration, or external forces. While HIGNN provides significant speedup, the quadratic scaling of its overall prediction cost (with respect to the total number of particles), due to intrinsically slow-decaying two-body HIs, limits its scalability. To achieve superior efficiency across all scales, in the present work we integrate $\mathcal{H}$-matrix techniques into HIGNN, reducing the prediction cost scaling to quasi-linear. Through comprehensive evaluations, we validate $\mathcal{H}$-HIGNN's accuracy, and demonstrate its quasi-linear scalability and superior computational efficiency. It requires only minimal computing resources; for example, a single mid-range GPU is sufficient for a system containing 10 million particles. Finally, we demonstrate $\mathcal{H}$-HIGNN's ability to efficiently simulate practically relevant large-scale suspensions of both particles and flexible filaments.
|
https://arxiv.org/abs/2505.08174
|
Academic Papers
|
svg
|
cb391f213be1136271da3d915b96695a2ce53765037b6b023615cf498ec24f01
|
2026-01-16T00:00:00-05:00
|
Evidence on the incompatibility of smoothed particle hydrodynamics and eddy viscosity models for large eddy simulations
|
arXiv:2506.08538v3 Announce Type: replace Abstract: In this work, we will present evidence for the incompatibility of Smoothed Particle Hydrodynamics (SPH) methods and eddy viscosity models. Taking a coarse-graining perspective, we physically argue that SPH methods operate intrinsically as Lagrangian Large Eddy Simulations (LES) for turbulent flows with strongly overlapping discretization elements. However, these overlapping elements in combination with numerical errors cause a significant amount of implicit subfilter stresses (SFS). Considering a Taylor-Green flow at $Re=10^4$, the SFS will be shown to be relevant where turbulent fluctuations are created, explaining why turbulent flows are challenging even for current SPH methods. Although one might hope to mitigate the implicit SFS using eddy viscosity models, we show a degradation of the turbulent transition process, which is rooted in the non-locality of these methods.
|
https://arxiv.org/abs/2506.08538
|
Academic Papers
|
svg
|
6e9201f68e79358993a7875736f299709724a418191f44b948e81dd9703c0850
|
2026-01-16T00:00:00-05:00
|
Spatio-temporal thermalization and adiabatic cooling of guided light waves
|
arXiv:2506.23536v2 Announce Type: replace Abstract: We propose and theoretically characterize three-dimensional spatio-temporal thermalization of a continuous-wave classical light beam propagating along a multi-mode optical waveguide. By combining a non-equilibrium kinetic approach based on the wave turbulence theory and numerical simulations of the field equations, we anticipate that thermalizing scattering events are dramatically accelerated by the combination of strong transverse confinement with the continuous nature of the temporal degrees of freedom. In connection with the blackbody catastrophe, the thermalization of the classical field in the continuous temporal direction provides an intrinsic mechanism for adiabatic cooling and, then, spatial beam condensation. Our results open new avenues in the direction of a simultaneous spatial and temporal beam cleaning.
|
https://arxiv.org/abs/2506.23536
|
Academic Papers
|
svg
|
3c6740e248febf8dae61476cfe39fd5b12cc6f071c3c93163b8de0c41589be23
|
2026-01-16T00:00:00-05:00
|
CycleGAN-Driven Transfer Learning for Electronics Response Emulation in High-Purity Germanium Detectors
|
arXiv:2507.09106v2 Announce Type: replace Abstract: High-Purity Germanium (HPGe) detectors are a key technology for rare-event searches such as neutrinoless double-beta decay (\ensuremath{0\nu\beta\beta}) and dark matter experiments. Pulse shapes from these detectors vary with interaction topology and thus encode information critical for event classification. Pulse shape simulations (PSS) are essential for modeling analysis cuts that distinguish signal events from backgrounds and for generating reliable simulations of energy spectra. Traditional PSS methods rely on a series of first-principles corrections to replicate the effect of readout electronics, requiring challenging fits over large parameter spaces and often failing to accurately model the data. We present a neural network architecture, the Cyclic Positional U-Net (https://github.com/aobol/CPU-Net), that performs translations of simulated pulses so that they closely resemble measured detector signals. Using a Cycle Generative Adversarial Network (CycleGAN) framework, this {Response Emulation Network} (REN) learns a data-driven mapping between simulated and measured pulses with high fidelity, without requiring a predetermined response model. We use data from a High-Purity Germanium (HPGe) detector with an inverted-coaxial point contact (ICPC) geometry to show that \texttt{CPU-Net} effectively captures and reproduces critical pulse shape features, allowing more realistic simulations without detector-specific tuning. \texttt{CPU-Net} achieves up to a factor-of-four improvement in distribution-level agreement for pulse shape parameter reconstruction, while preserving the topology-dependent information required for pulse-shape discrimination.
|
https://arxiv.org/abs/2507.09106
|
Academic Papers
|
svg
|
bec5d63a8bdfae61cf8f5cc3b15da503579edae9def106e20d1524bf2b5694f2
|
2026-01-16T00:00:00-05:00
|
Towards Quantum Accelerated Large-scale Topology Optimization
|
arXiv:2507.14478v2 Announce Type: replace Abstract: We present a new method that efficiently solves TO problems and provides a practical pathway to leverage quantum computing to exploit potential quantum advantages. This work targets on large-scale, multi-material TO challenges for three-dimensional (3D) continuum structures, beyond what have been addressed in prior studies. Central to this new method is the modified Dantzig-Wolfe (MDW) decomposition, which effectively mitigates the escalating computational cost associated with using classical Mixed-Integer Linear Programming (MILP) solvers to solve the master problems involved in TO, by decomposing the MILP into local and global sub-problems. Evaluated on 3D bridge designs, our classical implementation achieves comparable solution quality to state-of-the-art TO methods while reducing computation time by orders of magnitude. It also maintains low runtimes even in extreme cases where classical MILP solvers fail to converge, such as designs involving over 50 million variables. The computationally intensive local sub-problems, which are essentially Binary Integer Programming (BIP) problems, can potentially be accelerated by quantum computing via their equivalent Quadratic Unconstrained Binary Optimization (QUBO) formulations. Enabled by the MDW decomposition, the resulting QUBO formulation requires only sparse qubit connectivity and incurs a QUBO construction cost that scales linearly with problem size, potentially accelerating BIP sub-problem solutions by an additional order of magnitude. All observed and estimated speedups become increasingly significant with larger problem sizes and when moving from single-material to multi-material designs. This suggests that this new method, along with quantum computing, will play an increasingly valuable role in addressing the scale and complexity of real-world TO applications.
|
https://arxiv.org/abs/2507.14478
|
Academic Papers
|
svg
|
f8608c53c5000639a3617814da3e72c6caa06ad5c63162bfcc662dd35aa9c54e
|
2026-01-16T00:00:00-05:00
|
Single-photon loading of polar molecules into an optical trap
|
arXiv:2507.17521v2 Announce Type: replace Abstract: We propose a scheme to transfer molecules from a slow beam into an optical trap using only a single photon absorption and emission cycle. The efficiency of such a scheme is numerically explored for BaF using realistic experimental parameters. The technique makes use of the state-dependent potential in an external electric field to trap molecules from an initial velocity of order 10 m/s. A rapid optical transition at the point where the molecules come to a standstill in the electric field potential irreversibly transfers them into a ~7 mk optical lattice trap. For a pulsed Stark decelerated beam, we estimated the per-shot efficiency to be ~0.52% or up to ~10$^4$ molecules, with a potential factor 2 improvement when the fields are synchronously modulated with the arriving velocity components. The irreversibility of the scheme allows for larger numbers to be built up over time. Since this scheme does not rely on a closed cycling transition for laser cooling, it broadens the range of molecules that can be used for research on cold molecular chemistry, quantum information, and fundamental interactions in optical traps.
|
https://arxiv.org/abs/2507.17521
|
Academic Papers
|
svg
|
bb3c799316c77b084de8fc369c5c950d3f23a5f92c50fad29b8889a3f2e2dcb3
|
2026-01-16T00:00:00-05:00
|
Slip over liquid-infused gratings in the singular limit of a nearly inviscid lubricant
|
arXiv:2508.07449v2 Announce Type: replace Abstract: We consider shear-driven longitudinal flow of an exterior fluid over a periodic array of rectangular grooves filled with an immiscible interior fluid (the "lubricant"), the grooves being formed by infinitely thin ridges protruding from a flat substrate. The ratio $\lambda$ of the effective slip length to the semi-period is a function of the ratio $\mu$ of the interior to exterior viscosities and the ratio $h$ of the grooves depth to the semi-period. We focus on the limit $\mu\ll1$, which is singular for that geometry. We find that the viscous resistance to the imposed shear is dominated by a boundary layer of exponentially small extent about the ridge tips, resulting in the effective slip length scaling as $\mu^{-1/2}$ - not $\mu^{-1}$ as implied by intuitive arguments overlooking the tip contributions (and by proposed approximations in the literature). Analyzing that exponential region in conjunction with an integral force balance, we find the simple asymptotic approximation $\lambda\approx \mu^{-1/2}$; using conformal mappings, we also calculate the leading-order correction to that result, which introduces a dependence upon $h$. The ensuing asymptotic expansion breaks down for $h=O(\mu^{1/2})$, upon transitioning to a lubrication geometry. We accordingly conduct a companion asymptotic analysis in the distinguished limit of small $\mu$ and fixed $H=h/\mu^{1/2}$, which gives $\lambda\approx \mu^{-1/2}H/(1+H)$ as well as a closed-form leading-order correction to that approximation; the intuitive $\mu^{-1}$ scaling is accordingly only relevant to the regime $H\ll1$ corresponding to extremely shallow grooves. We demonstrate excellent agreement between our predictions and numerical solutions constructed using a boundary-integral formulation.
|
https://arxiv.org/abs/2508.07449
|
Academic Papers
|
svg
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.