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49877ec461f008f478c40950bec289556fabbbd0611c6b090f69aac8967cd61e
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2026-01-21T00:00:00-05:00
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Countable basis for free electromagnetic fields
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arXiv:2601.12911v1 Announce Type: cross Abstract: Polychromatic electromagnetic fields are typically expanded as integrals over monochromatic fields, such as plane waves, multipolar fields, or Bessel beams. However, monochromatic fields do not belong to the Hilbert space of free Maxwell fields, since their norms diverge. Moreover, the continuous frequency integrals involved in such expansions complicate the treatment of light--matter interactions via the scattering operator. Here, we identify and study a polychromatic basis for free Maxwell fields whose basis vectors belong to the Hilbert space. These vectors are defined as simultaneous eigenstates of four commuting operators with integer eigenvalues. As a consequence, the basis set is countable, and the Hilbert space is separable and isomorphic to $\ell^2$, the Hilbert space of square-summable sequences. Each basis vector represents a polychromatic single-photon wave with quantized energy and a wavelet--like temporal dependence. Three versions of this basis are defined: Regular, incoming, and outgoing. The fields of the regular basis are smooth in both space and time. The incoming and outgoing fields are likewise smooth, except at the spatial origin. These results support and motivate the use of countable bases for both the theoretical description and the practical computation of light--matter interactions.
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https://arxiv.org/abs/2601.12911
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Academic Papers
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ee4f331a7dbc02e342b6ca5b26c1b8bb37a8b03cbc8cc67ef421d84b85bec494
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2026-01-21T00:00:00-05:00
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Direct measurement of the Orderphobic Effect
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arXiv:2601.12935v1 Announce Type: cross Abstract: Fluctuation-induced forces, such as the Critical Casimir Effect (CCE), are fundamental mechanisms driving organization and self-assembly near second-order phase transitions. The existence of a comparable, universal force for systems undergoing a first-order transition has remained an unresolved fundamental question. The proposed Orderphobic Effect is one such potential mechanism. It arises from minimisation of the interfacial free energy between solutes that locally nucleate a disordered phase. Here, we report the first experimental demonstration and quantitative measurement of the Orderphobic Effect. Using a driven, non-equilibrium quasi-2D granular fluid undergoing a first-order order-disorder transition, we show that specifically designed solutes in an ordered phase nucleate a coexisting ``bubble'' of the disordered phase. By analysing its capillary fluctuations, we confirm that this phenomenon occurs due to the proximity to phase-coexistence, and we directly quantify the attractive force by measuring the interaction free energy between solutes. The observation of this general fluctuation-mediated force in a non-equilibrium steady state strongly supports its claimed universality. Our work establishes the Orderphobic Effect as the first-order equivalent to the CCE, providing a new, general route for controlling self-assembly and aggregation in soft matter and non-equilibrium systems.
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https://arxiv.org/abs/2601.12935
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Academic Papers
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60cdbbeff450c0e6adc341b12536430ff9249915633a96d8dbe611b62492e5b1
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2026-01-21T00:00:00-05:00
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PYVALE: A Fast, Scalable, Open-Source 2D Digital Image Correlation (DIC) Engine Capable of Handling Gigapixel Images
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arXiv:2601.12941v1 Announce Type: cross Abstract: Pyvale is an open-source software package that aims to become an all-in-one tool for sensor simulation, sensor uncertainty quantification, sensor placement optimization, and calibration/validation. Central to this is support for image-based sensors, with a dedicated Digital Image Correlation (DIC) module designed for both standalone use and integration within broader experimental design workflows. The design philosophy behind the DIC engine in Pyvale prioritizes a user-friendly Python interface with performant compiled code under the hood. This paper covers Pyvale's 2D DIC engine design, implementation, metrological performance compared to other DIC codes, and the unique ability to handle gigapixel size scanning electron microscope (SEM) images. Finally, we compare runtimes between Pyvale and other open-source DIC codes and show strong computational performance across a range of image resolutions and thread counts.
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https://arxiv.org/abs/2601.12941
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Academic Papers
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b6f7f1a6e7b6bad8bbd251646e5c48d060eccb0237c05b20f79f179b7a7a55fe
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2026-01-21T00:00:00-05:00
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Multiscale Prediction of Polymer Relaxation Dynamics via Computational and Data-Driven Methods
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arXiv:2601.12942v1 Announce Type: cross Abstract: We present a multiscale modeling approach that integrates molecular dynamics simulations, machine learning, and the Elastically Collective Nonlinear Langevin Equation (ECNLE) theory to investigate the glass transition dynamics of polymer systems. The glass transition temperatures (Tg) of four representative polymers are estimated using simulations and machine learning model trained on experimental datasets. These predicted Tg values are used as inputs to the ECNLE theory to compute the temperature dependence of structural relaxation times and diffusion coefficients, and the dynamic fragility. The Tg values predicted from simulations show good quantitative agreement with experimental data. While machine learning tends to slightly overestimate Tg, the resulting dynamic fragility values remain close to experimental fragilities. Overall, ECNLE calculations using these inputs agree well with broadband dielectric spectroscopy results. Our integrated approach provides a practical and scalable tool for predicting the dynamic behavior of polymers, particularly in systems where experimental data are limited.
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https://arxiv.org/abs/2601.12942
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Academic Papers
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204a6368a106ea93399d4a6149d5e729884732d0240b92230b9d3412ffd14890
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2026-01-21T00:00:00-05:00
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Non-Invasive Diagnosis for Clubroot Using Terahertz Time-Domain Spectroscopy and Physics-Constrained Neural Networks
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arXiv:2601.13069v1 Announce Type: cross Abstract: Clubroot, a major soilborne disease affecting canola and other cruciferous crops, is characterized by the development of large galls on the roots of susceptible hosts. In this study, we present the first application of terahertz time-domain spectroscopy (THz-TDS) as a non-invasive diagnosis tool in plant pathology. Compared with conventional molecular, spectroscopic, and immunoassay-based methods, THz-TDS offers distinct advantages, including non-contact, non-destructive, and preparation-free measurement, enabling rapid in situ screening of plant and soil samples. Our results demonstrate that THz-TDS can differentiate between healthy and clubroot-infected tissues by detecting both structural and biochemical alterations. Specifically, infected roots exhibit a blue shift in the refractive index in the low-frequency THz range, along with distinct peaks-indicative of disruptions in water transport and altered metabolic activity in both roots and leaves. Interestingly, the characteristic root swelling observed in infected plants reflects internal tissue disorganization rather than an actual increase in water content. Furthermore, a physics-constrained neural network is proposed to extract the main feature in THz-TDS. A comprehensive evaluation, including time-domain signals, amplitude and phase images, refractive index and absorption coefficient maps, and principal component analysis, provides enhanced contrast and spatial resolution compared to raw time-domain or frequency signals. These findings suggest that THz-TDS holds significant potential for early, non-destructive detection of plant diseases and may serve as a valuable tool to limit their spread in agricultural systems.
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https://arxiv.org/abs/2601.13069
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Academic Papers
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33b2ce23dc015432c4770154c669a30a83f142fd64d55baf86bd3dce20f81b97
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2026-01-21T00:00:00-05:00
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Polychronous Wave Computing: Timing-Native Address Selection in Spiking Networks
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arXiv:2601.13079v1 Announce Type: cross Abstract: Spike timing offers a combinatorial address space, suggesting that timing-based spiking inference can be executed as lookup and routing rather than as dense multiply--accumulate. Yet most neuromorphic and photonic systems still digitize events into timestamps, bins, or rates and then perform selection in clocked logic. We introduce Polychronous Wave Computing (PWC), a timing-native address-selection primitive that maps relative spike latencies directly to a discrete output route in the wave domain. Spike times are phase-encoded in a rotating frame and processed by a programmable multiport interferometer that evaluates K template correlations in parallel; a driven--dissipative winner-take-all stage then performs a physical argmax, emitting a one-hot output port. We derive the operating envelope imposed by phase wrapping and mutual coherence, and collapse timing jitter, static phase mismatch, and dephasing into a single effective phase-noise budget whose induced winner--runner-up margin predicts boundary-first failures and provides an intensity-only calibration target. Simulations show that nonlinear competition improves routing fidelity compared with noisy linear intensity readout, and that hardware-in-the-loop phase tuning rescues a temporal-order gate from 55.9% to 97.2% accuracy under strong static mismatch. PWC provides a fast routing coprocessor for LUT-style spiking networks and sparse top-1 gates (e.g., mixture-of-experts routing) across polaritonic, photonic, and oscillator platforms.
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https://arxiv.org/abs/2601.13079
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Academic Papers
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39d43bafcb931bd21f397348db74b97c2a4b8d473fd56098fdaf23be005621a4
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2026-01-21T00:00:00-05:00
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Comparison between explicit and implicit discretization strategies for a dissipative thermal environment
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arXiv:2601.13103v1 Announce Type: cross Abstract: We investigate strategies for simulating open quantum systems coupled to dissipative baths by comparing explicit wave function-based discretization [via multi-layer multi-configuration time-dependent Hartree (ML-MCTDH)] and the implicit density matrix-based master equation method [via tree tensor network hierarchical equations of motion (TTN-HEOM)]. For dissipative baths characterized by exponentially decaying bath correlation functions, the implicit discretization approach of HEOM -- rooted in bath correlation function decompositions -- proves significantly more efficient than explicit discretization of the bath into discrete harmonic modes. Explicit methods, like ML-MCTDH, require extensive mode discretization to approximate continuum baths, leading to computational bottlenecks. Case studies for two-level systems and a Fenna--Matthews--Olson complex model highlight TTN-HEOM's superiority in capturing dissipative dynamics with relaxations with a minimal number of auxiliary modes, while the explicit methods are as exact as the HEOM in pure dephasing regimes. This comparison is enabled by the TENSO package, which has both ML-MCTDH and TTN-HEOM implemented using the same computational structure and propagation strategy.
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https://arxiv.org/abs/2601.13103
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Academic Papers
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af38caf53ca2139d95461051c67cfb9c24554ad4886976ec2ffeb2f1ea75ed9d
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2026-01-21T00:00:00-05:00
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Noncontextual versus contextual interferometry
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arXiv:2601.13109v1 Announce Type: cross Abstract: Feynman famously said that single-particle interference is ``a phenomenon which is impossible to explain in any classical way, and which has in it the heart of quantum mechanics.'' In this paper we show that some of the phenomenology of interference can be reproduced in a ``classical'' way, by reproducing the Elitzur-Vaidman Bomb Tester (including their improved version) using an extension of the quantum simulation logic (QSL) formalism. Our result improves and simplifies a previous result by Catani \emph{et al}, which relies on a much more complicated extension involving a ``toy field theory.'' We also show that not all single-particle interference can be explained by such a simple extension (including that of Catani et al), by showing that Hofmann's three-path interferometer is ``nonclassical'' in a very specific sense: it violates a Kochen-Specker-noncontextual inequality. Given that both our extension of QSL and Catani et al's extension are \emph{noncontextual} -- so do not reproduce the contextual behaviour of Hofmann's three-path interferometer -- the behaviour of that interferometer is a proper example of a phenomenon that has in it the heart of quantum mechanics, according to Feynman.
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https://arxiv.org/abs/2601.13109
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Academic Papers
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ace00d951db95ce91fbbebbde3adc49f2c7b6650c2a830d28f0307fbe9b6be8a
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2026-01-21T00:00:00-05:00
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Disentangling the Discrepancy Between Theoretical and Experimental Curie Temperatures in Ferroelectric PbTiO$_3$
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arXiv:2601.13125v1 Announce Type: cross Abstract: Accurately predicting the Curie temperature ($T_c$) of ferroelectrics from first principles remains a major challenge, as theoretical estimates often fall significantly below experimental values. In this work, we investigate the origin of these discrepancies in the prototypical ferroelectric PbTiO$_3$ by performing extensive constant-pressure ab initio molecular dynamics (AIMD) simulations and benchmarking them against classical molecular dynamics (MD) using machine learning force fields (MLFFs) derived from first-principles data. Our results show that the underestimation of $T_c$ primarily stems from the limitations of the exchange-correlation functional, rather than inaccuracies in the MLFF fitting. We uncover a critical interplay between finite-size effects and the range of interatomic interactions: although short-range MLFFs appear to yield better agreement with experimental $T_c$, this improvement results from a fortuitous cancellation of errors. Incorporating explicit long-range interactions improves accuracy for larger supercells but ultimately leads to lower predicted $T_c$ values. These findings highlight that accurate finite-temperature predictions require not only high-quality training data and sufficiently large simulation cells, but also the explicit treatment of long-range interactions and improved exchange-correlation functionals.
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https://arxiv.org/abs/2601.13125
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Academic Papers
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d57ad9f93714cc61d98de44b639f91e2079da49e82c4e88ac978a910e88c3210
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2026-01-21T00:00:00-05:00
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Beta-AlGaO/Ga2O3 Tri-Gate MOSHEMT with 70GHz fT and 55GHz fmax
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arXiv:2601.13215v1 Announce Type: cross Abstract: We report Beta-AlGaO/Ga2O3 tri-gate heterostructure MOSHEMTs incorporating a thin 5 nm Al2O3 gate oxide layer for improved gate control and reduced leakage. The devices were fabricated on AlGaO/GaO heterostructures grown by ozone MBE on Fe-doped Ga2O3 (010) substrates. The tri-gate MOSHEMTs, with 1 micron-wide fins and Lg=155 nm, exhibit a peak current-gain cut-off frequency fT=70 GHz and a power-gain cut-off frequency fMAX=55 GHz.The fT.L product of 10.85 GHz-micron is the highest among reported Ga2O3 FETs to date. The devices show Vth =-0.5 V, an on/off ratio 10^6 I=80 mA/mm, a peak gm=60 mS/mm, and a low gate leakage current of 10^(-10) mA/mm at Vgs=0.5 V. Passivation with a 100 nm ALD Al2O3 layer effectively removes DC/RF dispersion and maintains stable operation under pulsed IV and repeated RF measurements. These results demonstrate the potential of tri-gate AlGaO/GaO MOSHEMTs for next-generation high-frequency and high-power applications.
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https://arxiv.org/abs/2601.13215
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Academic Papers
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823aa9199e5c288187ae73fd5a4197d0279424f7e08039cbb1b49e40ddb16537
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2026-01-21T00:00:00-05:00
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Anomalous diffusion and localization in a disorder-free atomic mixture
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arXiv:2601.13226v1 Announce Type: cross Abstract: The concept of random walk, in which particles or waves undergo multiple collisions with the microscopic constituents of a surrounding medium, is central to understanding diffusive transport across many research areas. However, this paradigm may break down in complex systems, where quantum interference and memory effects render the particle propagation anomalous, often fostering localization. Here we report on the observation of such anomalous dynamics in a minimal setting: an ultracold mass-imbalanced mixture of two fermionic gases in three dimensions. We release light impurities into a gas of heavier atoms and follow their evolution across different collisional regimes. Under strong interspecies interactions, by lowering the temperature we unveil a crossover from normal diffusion to subdiffusion. Simultaneously, a localized fraction of the light gas emerges, displaying no discernible dynamics over hundreds of collisions. Our findings, incompatible with the conventional Fermi-liquid picture, are instead captured by a model of an atom propagating through a (quasi-)static disordered landscape of point-like scatterers. These results highlight the key role of quantum interference in our mixture, which emerges as a versatile platform for exploring disorder-free localization phenomena.
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https://arxiv.org/abs/2601.13226
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Academic Papers
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4ef67e1df4944e6efff14b925f58bc3c36285462c2a2b3ab7a25b9da337772c0
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2026-01-21T00:00:00-05:00
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Pixelwise Uncertainty Quantification of Accelerated MRI Reconstruction
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arXiv:2601.13236v1 Announce Type: cross Abstract: Parallel imaging techniques reduce magnetic resonance imaging (MRI) scan time but image quality degrades as the acceleration factor increases. In clinical practice, conservative acceleration factors are chosen because no mechanism exists to automatically assess the diagnostic quality of undersampled reconstructions. This work introduces a general framework for pixel-wise uncertainty quantification in parallel MRI reconstructions, enabling automatic identification of unreliable regions without access to any ground-truth reference image. Our method integrates conformal quantile regression with image reconstruction methods to estimate statistically rigorous pixel-wise uncertainty intervals. We trained and evaluated our model on Cartesian undersampled brain and knee data obtained from the fastMRI dataset using acceleration factors ranging from 2 to 10. An end-to-end Variational Network was used for image reconstruction. Quantitative experiments demonstrate strong agreement between predicted uncertainty maps and true reconstruction error. Using our method, the corresponding Pearson correlation coefficient was higher than 90% at acceleration levels at and above four-fold; whereas it dropped to less than 70% when the uncertainty was computed using a simpler a heuristic notion (magnitude of the residual). Qualitative examples further show the uncertainty maps based on quantile regression capture the magnitude and spatial distribution of reconstruction errors across acceleration factors, with regions of elevated uncertainty aligning with pathologies and artifacts. The proposed framework enables evaluation of reconstruction quality without access to fully-sampled ground-truth reference images. It represents a step toward adaptive MRI acquisition protocols that may be able to dynamically balance scan time and diagnostic reliability.
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https://arxiv.org/abs/2601.13236
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Academic Papers
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632f21ff0ffa2845aea8c1966f65bc4edbe0205de96e17fd94d56c8c285fa0cf
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2026-01-21T00:00:00-05:00
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Rotating Magnetocaloric Effect in First-order Phase Transition Material Gd5Si2Ge2
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arXiv:2601.13239v1 Announce Type: cross Abstract: The rotating magnetocaloric effect (RMCE) induced by self-demagnetization has been investigated in the giant magnetocaloric effect (GMCE) material Gd$_5$Si$_2$Ge$_2$. This shape-dependent effect had thus far only been reported in pure Gd, marking this as the first analysis of the effect in a sample with a magnetostructural first-order phase transition. By rotating the applied magnetic field vector while keeping its intensity constant, the demagnetizing field within a high-aspect ratio sample changes significantly, resulting in a RMCE. We characterize RMCE by determining the adiabatic temperature change ($\Delta T_{ad}^{rot}$) directly through temperature measurements, and the isothermal entropy change ($\Delta S_M^{rot}$) via magnetometry and magnetostatic simulations. We obtain a remarkable maximum $\Delta T_{ad}^{rot}$ of 1.77 K for a constant external field of 0.8 T, higher than that obtained under 1.0 T. The magnetostatic simulations not only corroborate the highly non-monotonous field-dependence of $|\Delta S_{M}^{rot}|$, which reaches 95\% of its maximum value at 0.8 T, 6.12 J K$^{-1}$ kg$^{-1}$ for the experimentally measured shape, but also estimate a 35\% increase in the maximum $|\Delta S_{M}^{rot}|$ up to 8.67 J K$^{-1}$ kg$^{-1}$ in a simulated shape with higher aspect ratio.
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https://arxiv.org/abs/2601.13239
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Academic Papers
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d25cd1ca8501b0294c52f32bdae872ec126497dc4b8b76f89c76f20ce08e8e88
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2026-01-21T00:00:00-05:00
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Colossal low-field negative magnetoresistance in CaAl$_{2}$Si$_{2}$-type diluted magnetic semiconductors (Ba,K)(Cd,Mn)$_{2}$As$_{2}$
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arXiv:2601.13339v1 Announce Type: cross Abstract: We report the magnetic and magnetotransport properties of the layered CaAl$_2$Si$_2$-type diluted magnetic semiconductor (Ba$_{1-x}$K$_x$)(Cd$_{1-y}$Mn$_y$)$_2$As$_2$ over a broad Mn (spin) substitution range of $0.05 \le y \le 0.5$. K substitution introduces hole carriers, whereas Mn provides local moments, resulting in bulk ferromagnetism with Curie temperatures up to $\sim 17$ K. Intrinsic magnetic ordering is further supported by an anomalous Hall contribution and a specific-heat anomaly near $T_{\mathrm{C}}$. A key performance feature is a colossal negative magnetoresistance: for heavily Mn-doped compositions ($y \ge 0.3$), $\mathrm{MR}=[\rho(H)-\rho(0)]/\rho(0)$ reaches approximately $-100\%$ at 2 K and nearly saturates at a relatively low magnetic field of $\sim 0.35\,\mathrm{T}$. The combination of soft ferromagnetism, strong spin-charge coupling, and low-field MR saturation highlights (Ba,K)(Cd,Mn)$_2$As$_2$ as a promising bulk platform for low-temperature magnetoresistive functionalities.
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https://arxiv.org/abs/2601.13339
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Academic Papers
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dcde15f6ce53280638fcdefe2670333aeb8542eb2e24ff7ffc475495299acadf
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2026-01-21T00:00:00-05:00
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VAST: Vascular Flow Analysis and Segmentation for Intracranial 4D Flow MRI
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arXiv:2601.13393v1 Announce Type: cross Abstract: Four-dimensional (4D) Flow MRI can noninvasively measure cerebrovascular hemodynamics but remains underused clinically because current workflows rely on manual vessel segmentation and yield velocity fields sensitive to noise, artifacts, and phase aliasing. We present VAST (Vascular Flow Analysis and Segmentation), an automated, unsupervised pipeline for intracranial 4D Flow MRI that couples vessel segmentation with physics-informed velocity reconstruction. VAST derives vessel masks directly from complex 4D Flow data by iteratively fusing magnitude- and phase-based background statistics. It then reconstructs velocities via continuity-constrained phase unwrapping, outlier correction, and low-rank denoising to reduce noise and aliasing while promoting mass-consistent flow fields, with processing completing in minutes per case on a standard CPU. We validate VAST on synthetic data from an internal carotid artery aneurysm model across SNR = 2-20 and severe phase wrapping (up to five-fold), on in vitro Poiseuille flow, and on an in vivo internal carotid aneurysm dataset. In synthetic benchmarks, VAST maintains near quarter-voxel surface accuracy and reduces velocity root-mean-square error by up to fourfold under the most degraded conditions. In vitro, it segments the channel within approximately half a voxel of expert annotations and reduces velocity error by 39% (unwrapped) and 77% (aliased). In vivo, VAST closely matches expert time-of-flight masks and lowers divergence residuals by about 30%, indicating a more self-consistent intracranial flow field. By automating processing and enforcing basic flow physics, VAST helps move intracranial 4D Flow MRI toward routine quantitative use in cerebrovascular assessment.
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https://arxiv.org/abs/2601.13393
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Academic Papers
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4234d085ef46be5954c22e868536dee7e509e91ce1fa9792a51defbb50bb9602
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2026-01-21T00:00:00-05:00
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Wang-Landau study of lattice gases on geodesic grids
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arXiv:2601.13397v1 Announce Type: cross Abstract: We study a family of lattice-gas systems defined on semiregular grids, obtained by projecting the vertices of three different geodesic icosahedra onto a spherical surface. By using couplings up to third neighbors we explore various interaction patterns, ranging from core-corona repulsion to square-well attraction and short-range attractive, long-range repulsive potentials. The relatively small number of sites in each grid ($\sim 100$) enables us to compute the exact statistical properties of the systems as a function of temperature and chemical potential by Wang-Landau sampling. For each case considered we highlight the existence of distinct low-temperature ``phases'', featuring, among others, regular-polyhedral, cluster-crystal, and worm-like structures. We highlight similarities and differences between these motifs and those observed on the triangular lattice under the same conditions. Finally, we discuss the relevance of our results for the bottom-up realization of spherical templates with desired functionalities.
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https://arxiv.org/abs/2601.13397
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Academic Papers
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0fa162d111492cf707ec8448954916922fb71aa0fa300518cd835507125b8e3d
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2026-01-21T00:00:00-05:00
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Efficient and compact quantum network node based on a parabolic mirror on an optical chip
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arXiv:2601.13420v1 Announce Type: cross Abstract: We demonstrate a neutral atom networking node that combines high photon collection efficiency with high atom photon entanglement fidelity in a compact, fiber integrated platform. A parabolic mirror is used both to form the trap and to collect fluorescence from a single rubidium atom, intrinsically mode matching $\sigma$ polarized emitted photons to the fiber and rendering the system largely insensitive to small imperfections or drifts. The core optics consist of millimeter scale components that are pre aligned, rigidly bonded on a monolithic invacuum assembly, and interfaced entirely via optical fibers. With this design, we measure an overall photon collection and detection efficiency of $3.66\%$, from which we infer an overall collection efficiency of $6.6\%$ after the single--mode fiber coupling. We generate atom photon entangled states with a raw Bell state fidelity of 0.93 and an inferred fidelity of 0.98 after correcting for atom readout errors. The same node design has been realized in two independent setups with comparable performance and is compatible with adding high NA objective lenses to create and control atomic arrays at each node. Our results establish a robust, cavity free neutral atom interface that operates near the limit set by the collection optics numerical aperture and provides a practical building block for scalable quantum network nodes and repeaters.
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https://arxiv.org/abs/2601.13420
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Academic Papers
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e7669769106977cf42c5bbe6c3aab2ec866efe64a3e950024f1dba4e90b7c367
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2026-01-21T00:00:00-05:00
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Insights into $CO_{2}$ activation on defective ZnS surfaces
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arXiv:2601.13434v1 Announce Type: cross Abstract: In this work, we investigate $CO_{2}$ activation on ZnS using Near Ambient-Pressure X-ray photoelectron spectroscopy measurements (NAP-XPS) and density functional theory calculations (DFT). Our NAP-XPS experiments reveal that $CO_{2}$ adsorbs onto a defective ZnS surface upon heating above $473 \ K$ in a $CO_{2}$ atmosphere (up to $0.55 \ mbar$). The $CO_{2}$ adsorption fingerprint is detectable even after cooling to room temperature under ultra-high vacuum. Our DFT calculations suggest that $CO_{2}$ adsorption is energetically favorable on ZnS surfaces containing zinc vacancies, highlighting defect sites as key adsorption centers. Additionally, oxygen adsorption on a defective ZnS surface is exothermic, in contrast to the endothermic behavior observed on a defect-free surface. These findings contribute to a deeper understanding of defect-driven surface reactivity and may inform ZnS-based catalyst's design for $CO_{2}$ capture and reutilization.
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https://arxiv.org/abs/2601.13434
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Academic Papers
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5e5d3a58a2cd37acf9ba8b6b041368ceef903bd044dea39a021566380a69d191
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2026-01-21T00:00:00-05:00
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Dynamical Origin of (469219) Kamo`oalewa of Tianwen-2 Mission from the Main-Belt: $\nu_6$ Secular Resonance, Flora Family or 3:1 Resonance with Jupiter
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arXiv:2601.13585v1 Announce Type: cross Abstract: China's Tianwen-2 mission, launched on 29 May 2025, targets the near-Earth object (469219) Kamo`oalewa, an Earth quasi-satellite trapped in a 1:1 mean-motion resonance with our planet. Determining the origin of Kamo`oalewa is central to understanding the formation pathways and dynamical evolution of Earth's quasi-satellite population. Here we show a strong possibility of main-belt origin for Kamo`oalewa using long-term dynamical simulations. We examine three candidate source regions: the $\nu_6$ secular resonance ($\nu_6$), the 3:1 mean-motion resonance with Jupiter (3:1J MMR), and the Flora family. A total of 42,825 test particles were integrated over 100 Myr. We find that asteroids from all three regions can be transported onto Kamo`oalewa-like orbits, albeit with markedly different efficiencies. Particles originating near the $\nu_6$ show the highest transfer probability (3.31%), followed by the Flora family (2.54%) and the 3:1J MMR (0.39%). We further identify representative dynamical pathways linking these source regions to Earth quasi-satellite orbits. The Tianwen-2 spacecraft is expected to rendezvous with Kamo`oalewa in 2026, performing close-proximity operations and returning samples. The mission will provide decisive observational constraints on the asteroid's composition and physical properties, offering a critical test of its proposed origin.
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https://arxiv.org/abs/2601.13585
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Academic Papers
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29dcbcdcbb62d8c99882f7c8a27ffe91a801446ef3a668f96586cf3d90cf527d
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2026-01-21T00:00:00-05:00
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Theory for Entangled-Photons Stimulated Raman Scattering versus Nonlinear Absorption for Polyatomic Molecules
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arXiv:2601.13646v1 Announce Type: cross Abstract: Quantum entanglement offers an incredible resource for enhancing the sensing and spectroscopic probes. Here we develop a microscopic theory for the stimulated Raman scattering (SRS) using entangled photons. We demonstrate that the time-energy correlation of the photon pairs can optimize the signal for polyatomic molecules. Our results show that the spectral-line intensity of the entangled-photon SRS (ESRS) is of the same order of magnitude as the one for the entangled two-photon absorption (ETPA); the parameter window is thus identified to do so. Moreover, the vibrational coherence is found to play an important role for enhancing the ESRS against the ETPA intensity. Our work paves a firm road for extending the schemes of molecular spectroscopy with quantum light, based on the observation of the ETPA in experiments.
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https://arxiv.org/abs/2601.13646
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Academic Papers
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43c4611d0ba5de50779e57e2f9ad8659766db8806d2bf0d2edc98913a3206a19
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2026-01-21T00:00:00-05:00
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Hamiltonian hydrodynamic reductions of one-dimensional Vlasov equations
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arXiv:2601.13746v1 Announce Type: cross Abstract: We investigate Hamiltonian fluid reductions of the one-dimensional Vlasov-Poisson equation. Our approach utilizes the hydrodynamic Poisson bracket framework, which allows us to systematically identify fundamental normal variables derived from the analysis of the Casimir invariants of the resulting Poisson bracket. This framework is then applied to analyze several well-established Hamiltonian closures of the onedimensional Vlasov equation, including the multi-delta distribution and the waterbag models. Our key finding is that all of these seemingly distinct closures consistently lead to the formulation of a unified form of parametric closures: When expressed in terms of the identified normal variables, the parameterization across all these closures is revealed to be polynomial and of the same degree. All these parametric closures are uniquely generated from one of the moments, called $\mu$2, a cubic polynomial in the normal variables. This result establishes a structural connection between these different physical models, offering a path toward a more unified and simplified description of the one-dimensional Vlasov-Poisson dynamics through its reduced hydrodynamic forms with an arbitrary number of fluid variables.
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https://arxiv.org/abs/2601.13746
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85146a9a9d0a239de15cdbe0861cc7d47319574b9d8a272d536c3075c0efca78
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2026-01-21T00:00:00-05:00
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Comparative study of quartet superfluid state: Quartet Bardeen-Cooper-Schrieffer theory and generalized Nambu-Gor'kov formalism
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arXiv:2601.13825v1 Announce Type: cross Abstract: We theoretically investigate a quartet superfluid state in fermionic matter by using the quartet Bardeen-Cooper-Schrieffer (BCS) variational theory and the Green's function method. We demonstrate that the quartet BCS theory with the multiple-infinite-product ansatz successfully reproduces an exact four-body result in a one-dimensional four-component Fermi gas at the dilute limit, in contrast to the single-infinite-product ansatz. To see the validity of the quartet BCS state, we derive the self-consistent equation for the quartet superfluid order parameter within the generalized imaginary-time Nambu-Gor'kov formalism, which is found to be consistent with the quartet BCS variational equation. Moreover, by numerically computing the momentum-resolved single-particle spectral function in a one-dimensional system, we discuss how the single-particle spectra evolve with increasing the strength of the four-body cluster formation. We show that a coherent BCS-like quasiparticle branch on the weak-coupling side evolves into a strongly damped, continuum-dominated spectrum in the strong-coupling side, while nonzero quartet superfluid order parameter persists throughout the crossover regime. Our results would be useful for understanding beyond-BCS pairing effects and four-body cluster formations in fermionic systems in an interdisciplinary way.
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https://arxiv.org/abs/2601.13825
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a19aa0e7fa26574a648b453e327b7a9ecd0a988b6568377192eb09eddda5db68
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2026-01-21T00:00:00-05:00
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Bright Heralded Single-Photon Superradiance in a High-Density Thin Vapor Cell
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arXiv:2601.13909v1 Announce Type: cross Abstract: Superradiance is a hallmark of cooperative quantum emission, where radiative decay is collectively enhanced by coherence among emitters. Here, extending superradiant effects to photon pair generation from multi-level atoms, two-photon process offers a pathway to novel quantum light sources and a useful case for practical superradiance. We report bright heralded single-photon superradiance via spontaneous four-wave mixing in a 1-mm-long, high-density cesium vapor cell. By reducing the average distance between atoms in the atomic vapor to 0.29 times the idler photon wavelength, we observe a dramatic narrowing of the temporal two-photon wavefunction. This compression of temporal two-photon wavefunction evidences the superradiance of heralded photons in the collective two-photon emission dynamics. Furthermore, our heralded single-photon superradiance is accompanied by a coincidence-to-accidental ratio of 200 and the detected photon-pair counting exceeding 10^6 pairs/s. These findings establish dense thin atomic vapors as a practical, robust medium for realizing superradiant photon sources, with immediate relevance for quantum optics and the development of efficient photonic quantum technologies.
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https://arxiv.org/abs/2601.13909
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f26056afce80ebac4711f60a335ffcdca684328f9b1d60b0fd708efc23446d0b
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2026-01-21T00:00:00-05:00
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Universal composite phase gates with tunable target phase
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arXiv:2601.13923v1 Announce Type: cross Abstract: We present a systematic method for constructing universal composite phase gates with a continuously tunable target phase. Using a general Cayley--Klein parametrization of the single-pulse propagator, we design gates from an even number of nominal $\pi$ pulses and derive analytic phase families by canceling, order by order in a small deviation parameter, the leading contributions to the undesired off-diagonal element of the composite propagator, independently of the dynamical phase. The resulting sequences provide intrinsic robustness against generic control imperfections and parameter fluctuations and remain valid for arbitrary pulse shapes. Numerical simulations in a standard two-level model confirm high-order error suppression and demonstrate broad, flat high-fidelity plateaus over wide ranges of simultaneous pulse-area and detuning errors, highlighting the efficiency of the proposed universal composite phase gates for resilient phase control in quantum information processing.
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https://arxiv.org/abs/2601.13923
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1413705bbc01b9a678cd23c8ef7375d3ec47db989147cc409d64d4115b1094b3
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2026-01-21T00:00:00-05:00
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Ultra Compact low cost two mode squeezed light source
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arXiv:2601.13939v1 Announce Type: cross Abstract: Quantum-correlated states of light, such as squeezed states, constitute a fundamental resource for quantum technologies, enabling enhanced performance in quantum metrology, quantum information processing, and quantum communications. The practical deployment of such technologies requires squeezed-light sources that are compact, efficient, low-cost, and robust. Here we report a compact narrowband source of two-mode squeezed light at 795 nm based on four-wave mixing in hot 85Rb atomic vapor. The source is implemented in a small, modular architecture featuring a single fiber-coupled input, an electro-optic phase modulator combined with a single Fabry-Perot etalon for probe generation, and two free-space output modes corresponding to the signal and conjugate fields. Optimized for low pump power, the system achieves up to -8 dB of intensity-difference squeezing at an analysis frequency of 0.8 MHz with a pump power of only 300 mW. The intrinsic narrowband character of the generated quantum states makes this source particularly well suited for atomic-based quantum sensing and quantum networking, including interfaces with atomic quantum memories. Our results establish a versatile and portable platform for low-SWaP squeezed-light generation, paving the way toward deployable quantum-enhanced technologies.
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https://arxiv.org/abs/2601.13939
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d535dfbe71887d2567f805784b735fccdca841342431b5ce8c2d2dd491fa9fec
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2026-01-21T00:00:00-05:00
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Nonlinear competition avoidance favors coexistence in microbial populations
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arXiv:2601.13947v1 Announce Type: cross Abstract: Bacteria regulate their motility through a variety of mechanisms, including quorum sensing (QS) and other density-dependent responses mediated by diffusible signals. While nonlinear density-dependent motility is well known in active-matter theory to generate nonequilibrium spatial patterns, its consequences for the coexistence of growing, interacting species remain less explored. Here we develop a minimal spatially structured model for two strongly competing species in which local demographic interactions are coupled to an escape response: each species increases its motility nonlinearly (sigmoidal) with the local abundance of its competitor. We show that this sigmoidal motility regulation promotes optimal spatial self-organization and can sustain long term coexistence via segregation, even in parameter regimes that yield competitive exclusion in well-mixed Lotka-Volterra dynamics. On two-dimensional lattices, the interplay between demographic competition and density-dependent motility generates a range of emergent patterns, including regimes in which the weaker competitor counterintuitively has higher total abundance. Overall, our results identify nonlinear, competitor-induced motility as a fundamental mechanism capable of sustaining coexistence in competing microbial populations.
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https://arxiv.org/abs/2601.13947
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eb42af89c0ab494ab6c716346bfd710efd31a04615d73d8f078f91c8da5745cc
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2026-01-21T00:00:00-05:00
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Correlated domain and crystallographic orientation mapping in uniaxial ferroelectric polycrystals by interferometric vector piezoresponse force microscopy
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arXiv:2601.13982v1 Announce Type: cross Abstract: Ongoing advances in scanning probe microscopy techniques are continually expanding the possibilities for nanoscale characterization and correlated studies of functional materials. Here, we demonstrate how a recent extension of piezoresponse force microscopy (PFM), known as interferometric vector PFM, can be utilized for simultaneously mapping the local crystallographic orientations and the domain structure of distributed grains in uniaxial ferroelectric polycrystals. By shifting the laser beam position on the cantilever, direction-dependent piezoresponse signals are acquired analogous to classical vector PFM, but without the need to rotate the sample. Using polycrystalline ErMnO$_{3}$ as a model system, we demonstrate that the reconstructed piezoresponse vectors correlate one-to-one with the crystallographic orientations of the micrometer-sized grains, carrying grain-orientation and domain-related information. We establish a versatile approach for rapid, multimodal characterization of polycrystalline uniaxial ferroelectrics, enabling automated, high-throughput reconstruction of polarization and grain orientations with nanoscale precision.
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https://arxiv.org/abs/2601.13982
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ccbb0917267cf57ec4abf33e2a4239a1864cf588dfff8d8b32828b3405caa0a7
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2026-01-21T00:00:00-05:00
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Tripartite quantum correlations obtained by post-selection from twin beams
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arXiv:2601.14017v1 Announce Type: cross Abstract: Spatially-resolved photon counting of a twin beam performed by an iCCD camera allows for versatile tailoring the properties of the beams formed by parts of the original twin beam. Dividing the idler beam of the twin beam into three equally-intense parts and post-selecting by detecting a given number of photocounts in the whole signal beam we arrive at the idler fields exhibiting high degrees of nonclassicality and being endowed with tripartite quantum correlations. Nonclassicality is analyzed with the help of suitable nonclassicality witnesses and their corresponding nonclassicality depths. Suitable parameters are introduced to quantify quantum correlations. These parameters are analyzed as they depend on the field intensity. The experimental photocount histograms are reconstructed by the maximum-likelihood approach and the obtained photon-number distributions are compared with a suitable model in which the original twin beam is approximated by an appropriate multi-mode Gaussian field and undergoes the corresponding beams' transformations.
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https://arxiv.org/abs/2601.14017
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71ae58fa58fe1ea383c2dd32636d7049a446ecb685cd2a154ce1faf8b3f57033
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2026-01-21T00:00:00-05:00
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Binding Energies of Charged Particles on Dielectric Surfaces in Liquid Nitrogen
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arXiv:2601.14035v1 Announce Type: cross Abstract: A new approach for determining the binding energies of charged particles, such as ions and electrons, on dielectric surfaces in cryogenic liquids is introduced. The experimental technique outlined in this paper is employed to observe the buildup of charged particles on nonconductive surfaces using the electro-optic Kerr effect. The initial results of binding energy measurements on surfaces of deuterated tetraphenyl butadiene (dTPB)-coated and uncoated polymethyl methacrylate (PMMA) in liquid nitrogen are presented. Under these conditions, the ions or electrons displayed binding energies of less than 1 meV. Although these findings were obtained in liquid nitrogen, the methodology is not limited to cryogenic liquids and is applicable to a wide variety of fluids, with no essential dependence on temperature.
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https://arxiv.org/abs/2601.14035
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07a8ec6a647446c04c547e469c52b474f941bc904b0dad003de812125c1cabb8
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2026-01-21T00:00:00-05:00
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Evaluating state-of-the-art cloud quantum computers for quantum neural networks in gravitational waves data analysis
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arXiv:2601.14036v1 Announce Type: cross Abstract: In this work, we explore the possibility of using quantum computers provided for usage in cloud by big companies (such as IBM, IonQ, IQM Quantum Computers, etc.) to run our quantum neural network (QNN) developed for data analysis in the context of LISA Space Mission, developed with the Qiskit library in Python. Our previous work demonstrated that our QNN learns patterns in gravitational wave (GW) data much faster than a classical neural network, making it suitable for fast GW signal detection in future LISA data streams. Analyzing the fees from hardware providers like IBM Quantum, Amazon Braket and Microsoft Azure, we found that the fees for running the first segment of our QNN sum up to \$2000, \$60000, and \$1000000 respectively. Using free plans, we succeed to run the 3-qubit feature map of the QNN for one random data sample on {\fontfamily{qcr} \selectfont ibm\_kyoto} and {\fontfamily{qcr}\selectfont IQM Quantum Computers\_Garnet} quantum computers, obtaining a fidelity of 99\%; we could also run the first prediction segment of our QNN on {\fontfamily{qcr} \selectfont ibm\_kyoto}, implemented for 4 qubits, and obtained a prediction accuracy of 20\%. We queried providers such as IBM Quantum, Amazon Braket, Pasqal, and Munich Quantum Valley to obtain access to their plans, but, with the exception of Amazon Braket, our applications remain unanswered to this day. Other major setbacks in using the quantum computers we had access to included Qiskit library version issues (as in the cases of IBM Quantum and IQM Quantum Computers) and the frequent unavailability of the devices, as was the case with the Microsoft Azure provider. All the results presented in this paper were accumulated in 2024.
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https://arxiv.org/abs/2601.14036
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072275da3fa0b96d545eee2fc8ce58dfff15193b3be75ace3ef1c8e34b1e6541
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2026-01-21T00:00:00-05:00
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Onset of stripe order in classical fluids: Lessons from lattice-gas mixtures
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arXiv:2601.14082v1 Announce Type: cross Abstract: When two molecular species with mutual affinity are mixed together, various self-assembled phases can arise at low temperature, depending on the shape of like and unlike interactions. Among them, stripes -- where layers of one type are regularly alternated with layers of another type -- hold a prominent place in materials science, occurring e.g. in the structure of superconductive doped antiferromagnets. Stripe patterns are relevant for the design of functional materials, with applications in optoelectronics, sensing, and biomedicine. In a purely classical setting, an open question pertains to the features that spherically-symmetric particle interactions must have to foster stripe order. Here we address this challenge for a lattice-gas mixture of two particle species, whose equilibrium properties are exactly determined by Monte Carlo simulations with Wang-Landau sampling, in both planar and spherical geometry, and for equal chemical potentials of the species. Somewhat surprisingly, stripes can emerge from largely different off-core interactions, featuring various combinations of repulsive like interactions with a predominantly attractive unlike interaction. In addition to stripes, our survey also unveils crystals and crystal-like structures, cluster crystals, and networks, which considerably broaden the catalog of possible patterns. Overall, our study demonstrates that stripes are more widespread than generally thought, as they can be generated by several distinct mechanisms, thereby explaining why stripe patterns are observed in systems as diverse as cuprate materials, biomaterials, and nanoparticle films.
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https://arxiv.org/abs/2601.14082
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7c105082a243e31590c540128ec7827d19d99edb8a0b9d89992a20414db65d8d
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2026-01-21T00:00:00-05:00
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A Projective Algebra for Ansatz: Resolving Wigner's Puzzle and the Existence of External Realms
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arXiv:1306.2266v3 Announce Type: replace Abstract: Natural philosophy integrates scientific observation with abstract frameworks, often using a mathematical Ansatz to hypothesise about physical phenomena. Exploring the possibility of other universes, however, challenges assumptions that physical laws, like spacetime geometry, extend beyond our reality. This paper argues that mathematical abstractions, serving as a telescope beyond physical constraints, enable such reasoning. Through a projective algebra formalism (Section 4), we model the mechanism of Ansatz, abstractly describing physical objects. This yields a resolution to Wigner's unreasonable effectiveness via cardinality equivalence (Section 5) and clarifies terms like 'evidence' and 'existence' (Section 6) to align with the conventions used in physics. A Cantor-inspired paradox shows no universe can contain all mathematical abstractions (e.g., sets, numbers), as its power set exceeds it, necessitating an external abstract realm (Section 6.4). This logical necessity, which holds even in the context of alternative set theories like New Foundations, provides evidence for a minimal external universe as an abstract realm, supporting Mathematical Realism. This result is not specific to the formalism, as long as we accept that the principles of set theory are mathematically valid. As abstract entities elude empirical detection, logical evidence is apt, guiding future science and philosophy research and fostering interdisciplinary inquiry.
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https://arxiv.org/abs/1306.2266
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8873b7e9f6d583a969dc622d4e98d46436e19f6ba8e2ab76bda303ab65275480
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2026-01-21T00:00:00-05:00
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A detailed and unified treatment of spin-orbit systems using tools distilled from the theory of bundles
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arXiv:1501.02747v2 Announce Type: replace Abstract: We return to our study \cite{BEH} of invariant spin fields and spin tunes for polarized beams in storage rings but in contrast to the continuous-time treatment in \cite{BEH}, we now employ a discrete-time formalism, beginning with the $\rm{Poincar\acute{e}}$ maps of the continuous time formalism. We then substantially extend our toolset and generalize the notions of invariant spin field and invariant frame field. We revisit some old theorems and prove several theorems believed to be new. In particular we study two transformation rules, one of them known and the other new, where the former turns out to be an $SO(3)$-gauge transformation rule. We then apply the theory to the dynamics of spin-$1/2$ and spin-$1$ particle bunches and their density matrix functions, describing semiclassically the particle-spin content of bunches. Our approach thus unifies the spin-vector dynamics from the T-BMT equation with the spin-tensor dynamics and other dynamics. This unifying aspect of our approach relates the examples elegantly and uncovers relations between the various underlying dynamical systems in a transparent way. As in \cite{BEH}, the particle motion is integrable but we now allow for nonlinear particle motion on each torus. Since this work is inspired by notions from the theory of bundles, we also provide insight into the underlying bundle-theoretic aspects of the well-established concepts of invariant spin field, spin tune and invariant frame field. Since we neglect, as is usual, the Stern-Gerlach force, the underlying principal bundle is of product formso that we can present the theory in a fashion which does not use bundle theory. Nevertheless we occasionally mention the bundle-theoretic meaningof our concepts and we also mention the similarities with the geometrical approach to Yang-Mills Theory.
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https://arxiv.org/abs/1501.02747
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0154835c7df40000be9cb1575d16f8ecc6dd32f7a5399a379c0bf4c0bda30ddd
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2026-01-21T00:00:00-05:00
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Poynting Vector Spin in Gyromagnetic Medium and its Impact on Backward Power Flow in Waveguiding Structures
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arXiv:2310.15867v3 Announce Type: replace Abstract: This paper investigates the reactive power and spin of instantaneous Poynting vector in the bulk of gyromagnetic medium. It is shown that the gyromagnetic medium introduces a spin in the Poynting vector. The spin of the instantaneous Poynting vector and the relative strengths of the real and reactive power components are quantified using the Stokes plot method. Using this technique we investigate the presence of backward power propagation in a ferrite-filled waveguide. We present an analytical expression to locate the crossover point separating the forward and backward power propagation, where the real power propagation has a null. We further show that this backward power propagation leads to corresponding opposing surface currents on a waveguide plate of the ferrite-filled waveguide, while the potential difference between the two plates remain symmetric.
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https://arxiv.org/abs/2310.15867
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d9ed1042555493fdbdb0699194803ce1b1eaaa0ad12f2e646aa573765f598cc7
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2026-01-21T00:00:00-05:00
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Graduate education in optics in Japan and the United States: impact of funding levels on educational structure
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arXiv:2401.08933v2 Announce Type: replace Abstract: We compare the optical science & engineering graduate-level educational environments at two universities in two countries: Utsunomiya University in Japan, and the University of Arizona in the United States. Because the university education systems in the two countries are so different, we also explain how financial resources drive many of these differences and discuss how these impact student and faculty life.
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https://arxiv.org/abs/2401.08933
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9fd4cec074b2490873b7aeb0c274c1fffb51c8d758af8c9c231e5a09f781c1e3
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2026-01-21T00:00:00-05:00
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Under-coverage in high-statistics counting experiments with finite MC samples
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arXiv:2401.10542v3 Announce Type: replace Abstract: We consider the problem of setting confidence intervals on a parameter of interest from the maximum-likelihood fit of a physics model to a binned data set with a large number of bins, large event-counts per bin, and in the presence of systematic uncertainties modeled as nuisance parameters. We use the profile-likelihood ratio for statistical inference and focus on the case in which the model is determined from Monte Carlo simulated samples of finite size. We start by presenting a toy model in which the properties of widely used approximations of the profile-likelihood ratio in the asymptotic limit, which are commonly expected to hold in the high-statistics regime, are manifestly broken even if the numbers of events per bin in both the data and simulated samples are seemingly large enough to warrant their validity. We then move to the general setting to show how statistical uncertainties in the Monte Carlo predictions can affect the coverage of confidence intervals constructed in the asymptotic approximation always in the same direction, namely they lead to systematic under-coverage.
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https://arxiv.org/abs/2401.10542
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fd53e51d6ba8805977354e5ec05459e00d7bd8e93da360e2376b420239c4635a
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2026-01-21T00:00:00-05:00
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Orders-of-magnitude reduction in photonic mode volume by nano-sculpting
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arXiv:2406.16461v2 Announce Type: replace Abstract: Achieving strong light-matter interaction is important for studying and exploiting several physics phenomena. The light-matter interaction strength depends on the optical field intensity in the interaction region, often measured by the Purcell factor, which for a single emitter is proportional to the spectral confinement, quantified by the cavity quality factor $Q$, and inversely proportional to the spatial localization of light, quantified by the optical model volume $V$, $F \propto \frac{Q}{V}$. While plasmonic (metallic) devices can support extreme spatial light confinement, ohmic losses reduce the cavity lifetime, thereby limiting the achievable spectral confinement. It is therefore of both practical and fundamental interest to explore the potential for achieving extreme spatial light confinement in (near) loss-less dielectric environments. Employing topology optimization we explore the limits of spatial light confinement in dielectric environments when allowing for three-dimensional sculpted dielectric nanostructures. Here we discover structures supporting optical modes that are concentrated in material (air) with mode volumes that are three (four) orders of magnitude below the so-called diffraction limit, $V_{\textbf{r}_0} \approx 4 \cdot 10^{-4} \left[\lambda/(2 n)\right]^3 \left( V_{\textbf{r}_0} \approx 3 \cdot 10^{-5} \left[\lambda/2\right]^3\right)$. Remarkably, we further discover that encapsulating the nanostructure by ellipsoidal shells enables seemingly unbounded enhancement of the mode quality factor ($Q > 10^8$ demonstrated numerically) leading to theoretical Purcell factor enhancement above $10^{11}$. It is established how $V_{\textbf{r}_0}$ and $Q$ depend on the choice of material platform, device volume, minimum feature size and the number of shells. Finally a study of sensitivity towards geometric variations is presented, revealing robust behaviour.
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https://arxiv.org/abs/2406.16461
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de01ac0c320dc86e04a9954f766cf20e3f1649527fdd50f753118387bd254acd
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2026-01-21T00:00:00-05:00
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Pattern formation and spatiotemporal chaos in relativistic degenerate plasmas
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arXiv:2410.02568v2 Announce Type: replace Abstract: We numerically study the nonlinear interactions of high-frequency circularly polarized electromagnetic (EM) waves and low-frequency electron-acoustic (EA) density perturbations driven by the EM wave ponderomotive force in relativistic plasmas {(moderate, strong, and ultra-relativistic)} with two groups of electrons--the population of relativistic degenerate dense electrons (bulk plasma) and the sparse relativistic nondegenerate (classical) electrons, and immobile singly charged positive ions. By pattern selection, we show that many solitary patterns can be generated and drenched through modulational instability of EM waves at different spatial length scales and that the EM wave radiation spectra emanating from compact astrophysical objects may not settle into stable envelope solitons but into different incoherent states, including the emergence of temporal and spatiotemporal chaos due to collisions and fusions among the patterns with strong EA wave emission. The appearance of these states is confirmed by analyzing the Lyapunov exponent spectra, correlation function, and mutual information {as quantitative evidence}. As a result, the redistribution of wave energy from initially exciting many solitary patterns at large scales to a few new incoherent patterns with small wavelengths in the system occurs, leading to the onset of turbulence in astrophysical plasmas.
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https://arxiv.org/abs/2410.02568
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25fbb16969cda43657ce937c6b5696989be03183dd792aaee8d7a647a3085164
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2026-01-21T00:00:00-05:00
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Dispersion relations of generalized one-dimensional phononic crystals
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arXiv:2410.04549v2 Announce Type: replace Abstract: We present a comprehensive method for determining {both exact and approximate} dispersion {relations} for one-dimensional {resonant phononic} crystals, applicable to a wide range of structures, regardless of their specific characteristics. This general framework employs a unified mathematical model, referred to as generalized {one-dimensional (1D) phononic crystal}, in which {different} types of {waves} and scatterers{/resonators} {can be} {considered} by adjusting certain parameters. The generalized {1D phononic crystal} consists of both a host {one-dimensional} homogeneous elastic {material} with physical properties represented in matrix form and an arbitrary set of scatterers {within the unit cell,} including resonators (discrete and continuous), small material inclusions, or variations in cross-sectional area. Based on general assumptions, {and imposing the periodicity and Bloch solutions} we develop a matrix-based algorithm utilizing the plane wave expansion method to derive the solution. Additionally, we propose an iterative procedure that provides analytical expressions for the first- and second-order terms, particularly useful in the context of weak scattering. The convergence conditions of the method are rigorously defined. The {efficiency of the} approach is demonstrated through several numerical examples, highlighting its versatility in different waveguide configurations and scattering scenarios.
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https://arxiv.org/abs/2410.04549
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5d10357ec4058b9753f873f6f5982195a0da706222a6304930dffdd0d7c30f09
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2026-01-21T00:00:00-05:00
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Comparison of Generative Learning Methods for Turbulence Surrogates
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arXiv:2411.16417v4 Announce Type: replace Abstract: Numerical simulations of turbulent flows present significant challenges in fluid dynamics due to their complexity and high computational cost. High resolution techniques such as Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) are generally not computationally affordable, particularly for technologically relevant problems. Recent advances in machine learning, specifically in generative probabilistic models, offer promising alternatives as surrogates for turbulence. This paper investigates the application of three generative models - Variational Autoencoders (VAE), Deep Convolutional Generative Adversarial Networks (DCGAN), and Denoising Diffusion Probabilistic Models (DDPM) - in simulating a von K\'arm\'an vortex street around a fixed cylinder projected into 2D, as well as a real-world experimental dataset of the wake flow of a cylinder array. Training data was obtained by means of LES in the simulated case and Particle Image Velocimetry (PIV) in the experimental case. We evaluate each model's ability to capture the statistical properties and spatial structures of the turbulent flow. Our results demonstrate that DDPM and DCGAN effectively replicate all flow distributions, highlighting their potential as efficient and accurate tools for turbulence surrogacy. We find a strong argument for DCGAN, as although they are more difficult to train (due to problems such as mode collapse), they show the fastest inference and training time, require less data to train compared to VAE and DDPM, and provide the results most closely aligned with the input stream. In contrast, VAE train quickly (and can generate samples quickly) but do not produce adequate results, and DDPM, whilst effective, are significantly slower at both, inference and training time.
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https://arxiv.org/abs/2411.16417
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cfa13d28f7868b14acfa8264ef068eecdbef9a1a95f833f827573e5281b1a9f3
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2026-01-21T00:00:00-05:00
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Exploring Nonlinear Drift Waves: Limiting Cases and Dynamics
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arXiv:2501.15873v3 Announce Type: replace Abstract: A general equation for drift waves is derived incorporating both nonlinear electron density perturbation and ion vorticity effects. It is emphasized that the well-known Hasegawa-Mima (HM) equation for drift waves [A. Hasegawa and K. Mima, Phys. Fluids 21, 87 (1978)] includes only the ion vorticity term and neglects nonlinear electron density contribution that naturally arises from the electrons Boltzmann response. If ion vorticity term is ignored, then the general nonlinear equation reduces to an equation which can give two-dimensional soliton solution under an appropriate coordinate transformation. Furthermore, under the assumption that the normalized electrostatic potential depends only on one spatial coordinate along the predominant propagation direction, i.e. $\Phi = \Phi(y)$, the equation reduces to one-dimensional KdV equation [H. Saleem, Phys. Plasmas 31, 112102 (2024)]. Conversely, if the nonlinear electron density term is artificially suppressed and a two-dimensional potential $\Phi = \Phi(x, y)$ is considered, the equation reduces to Hasegawa-Mima equation supporting dipolar vortex solution. Because the HM equation ignores nonlinear electron density term, it cannot support one- or two-dimensional soliton solutions. Finally, the limiting forms of the general nonlinear equation are also briefly discussed using the reductive perturbation method (RPM).
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https://arxiv.org/abs/2501.15873
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4ee678b511f9bcc15bb45f652e7bf0472675cef14a3fd0078072c3036604cef2
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2026-01-21T00:00:00-05:00
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Removal of radon progeny from delicate surfaces
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arXiv:2502.04479v2 Announce Type: replace Abstract: $^{210}Po$ $\alpha$-decay driven neutron background is a concern for many rare event search experiments. It is a difficult to control background because its radiogenic component depends on the air exposure history of parts. In this study, we demonstrate that about half of the radon progeny $^{210}Po$ can be removed from copper and silicon surfaces relatively easily by wiping a copper sample with acetone wetted tissue and a silicon detector with acetone soaked cotton balls. For a copper sample we demonstrate that long-lived $^{210}Pb$ is removed with similar effectiveness. For copper, allocated the longest counting time, additional wiping was found to be largely ineffective. For silicon, the removal effectiveness has large uncertainties. Additional cleaning showed a small but statistically significant effect. Capitalizing on this trivial cleaning step will allow experiments to relax their requirements on the allowable air exposure time during construction, leading to cost and time savings.
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https://arxiv.org/abs/2502.04479
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72c0c1952b9402d36aca38897438d8ee744ba7debaeb4e69281bd0574a9820bc
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2026-01-21T00:00:00-05:00
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Localized necking under global compression in two-scale metallic hierarchical solids
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arXiv:2503.05498v2 Announce Type: replace Abstract: Hierarchically structured cellular solids have attracted increasing attention for their superior mass-specific mechanical properties. Using a remeshing-based continuum finite element (FE) framework, we reveal that two-scale metallic hierarchical solids exhibit a distinct, localized deformation mode that involves necking and fracture of microscale tension members even at small global compressive strains (3-5%). The tensile failure is always preceded by plastic buckling of a complementary compression member. This combined necking-buckling (NB) mode critically underlies the collapse of hexagon-triangle (HTH) hierarchical lattices over a wide range of relative densities and length-scale ratios and is also seen in diamond-triangle (DTH) lattices. In lattices with very slender microscale members, necking is prevented by a competing failure mode that involves coordinated buckling (CB) of multiple members. Our custom remeshing FE framework is critical to resolve the localized large plastic strains, ductile failure, and complex local modes of deformation (including cusp formation) that are characteristic of the NB mode. A theoretical buckling analysis supports the inevitability of the NB and CB modes in HTH lattices. The occurrence of the NB mode has consequences for energy absorption by two-scale hierarchical solids, and hence influences their design.
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https://arxiv.org/abs/2503.05498
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693eea22f47d4156d9fb67c2407dd392d81ef17f29659523b8a70ef343840869
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2026-01-21T00:00:00-05:00
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Global evidence for a consistent spatial footprint of intra-urban centers
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arXiv:2503.06445v2 Announce Type: replace Abstract: Urban space is highly heterogeneous, with population and human activities concentrating in localized centers. However, the global organization of such intra-urban centers remains poorly understood due to the lack of consistent, comparable data. Here we develop a scalable geospatial framework to identify intra-urban activity centers worldwide using nighttime light observations. Applying this approach to more than 9,500 cities, we construct a high-resolution global dataset of over 15,000 centers. We uncover a striking regularity: despite vast differences in city size, regional development, and population density, the built-up area associated with individual centers remains remarkably consistent. Across cities, total urban area scales proportionally with the number of centers, yielding a stable mean spatial footprint. This regularity holds at the micro-scale, where Voronoi-based service areas exhibit a characteristic size that is persistent across countries and independent of local population concentration. As a geometric consequence, this polycentric multiplication maintains stable average distances to the nearest center as cities expand, preventing the accessibility decay inherent in monocentric growth. These findings reveal a universal organizing principle whereby urban expansion is accommodated through the replication of activity centers with a consistent spatial extent, providing a new empirical foundation for understanding the nature of urban growth.
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https://arxiv.org/abs/2503.06445
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26f1302caa0126441bbc3216f952d7bd9861e59f7c3ca54a1587de48c0a6ccb0
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2026-01-21T00:00:00-05:00
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Vib2Mol: from vibrational spectra to molecular structures-a unified deep learning framework
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arXiv:2503.07014v4 Announce Type: replace Abstract: There will be a paradigm shift in chemical and biological research, to be enabled by autonomous, closed-loop, real-time self-directed decision-making experimentation. Spectrum-to-structure correlation, which is to elucidate molecular structures with spectral information, is the core step in understanding the experimental results and to close the loop. However, current approaches usually divide the task into either database-dependent retrieval and database-independent generation and neglect the inherent complementarity between them. In this study, we proposed Vib2Mol, a unified deep learning framework designed to flexibly handle diverse spectrum-to-structure tasks according to the available prior knowledge by bridging the retrieval and generation. Empowered by our coarse-to-fine retrieval and generate-then-rerank strategies, Vib2Mol not only achieves state-of-the-art performance in analyzing theoretical Infrared and Raman spectra, but also outperform previous models on experimental data. Moreover, our model demonstrates promising capabilities in predicting reaction products and sequencing peptides, enabling vibrational spectroscopy a potential guide for autonomous scientific discovery workflows.
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https://arxiv.org/abs/2503.07014
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23accadbf975137d3f7c75eb948221cd3d50fb4e37d0dd01ecf22ff8318c5acc
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2026-01-21T00:00:00-05:00
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Micromagnetorotation effects in micropolar magnetohydrodynamic blood flow through stenosis
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arXiv:2504.13678v2 Announce Type: replace Abstract: This study presents a numerical investigation of a 3D micropolar magnetohydrodynamic (MHD) blood flow through stenosis, with and without the effects of micromagnetorotation (MMR). MMR refers to the magnetic torque caused by the misalignment of the magnetization of magnetic particles in the fluid with the magnetic field, which affects the internal rotation (microrotation) of these particles. Blood can be modeled as a micropolar fluid with magnetic particles due to the magnetization of erythrocytes. In this manner, this study analyzes important flow features, i.e., streamlines, vorticity, velocity, microrotation, wall shear stress, and pressure drop under varying stenosis, hematocrit levels, and magnetic fields, using two newly developed transient OpenFOAM solvers epotMicropolarFoam and epotMMRFoam. Results indicate that micropolar effects become more pronounced at severe stenosis due to the significant reduction in artery size, resulting also in higher wall shear stress and pressure drop. Furthermore, when MMR is disregarded, the magnetic field does not significantly alter blood flow, regardless of its intensity, due to the minimal impact of the Lorentz force on blood. Conversely, MMR substantially affects blood flow, particularly at higher hematocrit levels and severe stenoses, leading to reductions of up to 30% in velocity and vorticity and up to 99.9% in microrotation and higher wall shear stress and pressure drop. Simultaneously, any vortices or disturbances are dampened. These findings underscore the critical role of MMR (which was ignored so far) in altering flow behavior in stenosed arteries, suggesting that it should be considered in future MHD micropolar blood flow studies.
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https://arxiv.org/abs/2504.13678
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53f2fecde2b902b9a2229ab90654ddb9c42d7d36d4d525f2b7fb0ee3f63e495a
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2026-01-21T00:00:00-05:00
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On the development of OpenFOAM solvers for simulating MHD micropolar fluid flows with or without the effect of micromagnetorotation
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arXiv:2504.14543v4 Announce Type: replace Abstract: Any micropolar fluid containing magnetic particles, such as blood or ferrofluids, subjected to an external magnetic field experiences a magnetic torque due to the misalignment between particle magnetization and the magnetic field. This effect, known as micromagnetorotation (MMR), remains underexplored in blood flows where erythrocyte magnetization is often neglected. To investigate this, two transient OpenFOAM solvers were developed: epotMicropolarFoam, for incompressible, laminar magnetohydrodynamic (MHD) micropolar flows, and epotMMRFoam, which extends it by incorporating MMR. Both solvers use the PISO algorithm for pressure-velocity coupling and adopt the low magnetic Reynolds number approximation. Micropolar effects are modeled by including the microrotation-vorticity difference in the momentum equation and solving the internal angular momentum equation. In epotMMRFoam, the MMR term is added to this equation, and a constitutive equation for magnetization is also solved. Validation against analytical MHD micropolar Poiseuille flow showed excellent accuracy (error less than 2 percent). Including MMR led to notable reductions in velocity (up to 40 percent) and microrotation (up to 99.9 percent), especially under strong magnetic fields and high hematocrit. Without MMR, magnetic effects were minimal due to the low electrical conductivity of blood. Simulations of 3D MHD artery and 2D MHD aneurysm flows confirmed these findings. In aneurysm geometries, MMR suppressed vortex cores, indicating strong stabilizing and shear-dampening effects. These solvers show high potential for biomedical applications such as magnetic hyperthermia and targeted drug delivery.
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https://arxiv.org/abs/2504.14543
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a3697ee3e76463d042adfa6b22bddee6a64533b03619520fdd3a22ec8eaebe00
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2026-01-21T00:00:00-05:00
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Coalescence of viscoelastic sessile drops: the small and large contact angle limits
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arXiv:2505.02226v2 Announce Type: replace Abstract: The coalescence and breakup of drops are classic examples of flows that feature singularities. The behavior of viscoelastic fluids near these singularities is particularly intriguing - not only because of their added complexity, but also due to the unexpected responses they often exhibit. In particular, experiments have shown that the coalescence of viscoelastic sessile drops can differ significantly from their Newtonian counterparts, sometimes resulting in a sharply defined interface. However, the mechanisms driving these differences in dynamics, as well as the potential influence of the contact angle are not fully known. Here, we study two different flow regimes effectively induced by varying the contact angle and demonstrate how that leads to markedly different coalescence behaviors. We show that the coalescence dynamics is effectively unaltered by viscoelasticity at small contact angles. The Deborah number, which is the ratio of the relaxation time of the polymer to the timescale of the background flow, scales as $\theta^3$ for $\theta \ll 1$, thus rationalizing the near-Newtonian response. On the other hand, it has been shown previously that viscoelasticity dramatically alters the shape of the interface during coalescence at large contact angles. We study this large contact angle limit using experiments and 2D numerical simulations of the equation of motion. We show that the departure of the coalescence dynamics from the Newtonian case is a function of the Deborah number and the elastocapillary number, which is the ratio between the shear modulus of the polymer solution and the characteristic stress in the fluid.
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https://arxiv.org/abs/2505.02226
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59b4193fa4dab2cbce5bc26ed50a358a6543121c0caa562c390a9f3c5a08e9af
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2026-01-21T00:00:00-05:00
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Linear Analysis of Stochastic Verlet-Type Integrators for Langevin Equations
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arXiv:2505.04100v2 Announce Type: replace Abstract: We provide an analytical framework for analyzing the quality of stochastic Verlet-type integrators for simulating the Langevin equation. Focusing only on basic objective measures, we consider the ability of an integrator to correctly simulate two characteristic configurational quantities of transport, a) diffusion on a flat surface and b) drift on a tilted planar surface, as well as c) statistical sampling of a harmonic potential. For any stochastic Verlet-type integrator expressed in its configurational form, we develop closed form expressions to directly assess these three most basic quantities as a function of the applied time step. The applicability of the analysis is exemplified through twelve representative integrators developed over the past five decades, and algorithm performance is conveniently visualized through the three characteristic measures for each integrator. The GJ set of integrators stands out as the only option for correctly simulating diffusion, drift, and Boltzmann distribution in linear systems, and we therefore suggest that this general method is the one best suited for high quality thermodynamic simulations of nonlinear and complex systems, including for relatively high time steps compared to simulations with other integrators.
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https://arxiv.org/abs/2505.04100
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b2daa498a558c0cea00ccd0c2b03d7e6079d5a7fcbebfd13fb8f4c189ff20b87
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2026-01-21T00:00:00-05:00
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On the concentration distribution in turbulent thermals
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arXiv:2505.21707v2 Announce Type: replace Abstract: Turbulent thermals emerge in a wide variety of geophysical and industrial flows, such as atmospheric cumulus convection and pollutant dispersal in oceans and lakes. When a buoyant fluid mass rises, or sinks, heat and mass transfers occur by the engulfment of the fresh surrounding fluid inside the thermal - a process that spans over multiple scales from macroscopic entrainment of ambient fluid to microscopic diffusive processes. Turbulent thermals are typically investigated through their integral properties (radius, depth, entrainment rate). However, mixing processes depend on the internal distribution of concentration or temperature inside a thermal, which remains poorly constrained. Here, we use laboratory fluid dynamics experiments and direct numerical simulations to investigate the mixing of a passive scalar in turbulent thermals with large Reynolds numbers. We track the evolution of the concentration field, computing its moments and the probability density function. The concentration distribution exhibits self-similarity over time, except at high concentrations, possibly because of the presence of undiluted cores. These distributions are well approximated by an exponential probability density function. Although diffusion has a strong effect on the spatial structure of the concentration field, we observe no significant effect of diffusivity on the concentration distributions in the investigated range of Peclet numbers.
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https://arxiv.org/abs/2505.21707
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43b3ac1165b4147cc2d57597f806ecb6035da4f439d2aac1a210badb46e5415b
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2026-01-21T00:00:00-05:00
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Compression, simulation, and synthesis of turbulent flows with tensor trains
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arXiv:2506.05477v2 Announce Type: replace Abstract: Numerical simulations of turbulent fluids are paramount to real-life applications, from predicting and modeling flows to diagnostic purposes in engineering. However, they are also computationally challenging due to their intrinsically non-linear dynamics, which require a very high spatial resolution to accurately describe them. A promising idea is to represent flows on a discrete mesh using tensor trains (TTs), featuring a convenient scaling of the number of parameters with the mesh size. However, it is unclear how the compression power of TTs is affected by the complexity of the flows, as measured by the Reynolds number. In fact, no comprehensive analysis of how the TT representation affects the turbulent properties has yet been carried out. We fill this gap by analyzing TTs as an Ansatz to compress, simulate, and generate 3D snapshots with turbulent-like features. Specifically, we first investigate the effect of TT compression on key turbulence signatures, such as the energy spectrum, the PDF of velocity increments, and flatness. Second, we extend the 2D TT-solver introduced in [1] to a 3D cubic domain with periodic boundary conditions. We use it to simulate the incompressible Navier-Stokes dynamics at $Re_{\lambda}=315$ for a total of 9-10 Kolmogorov turnover times, showcasing the numerical stability of the TT-solver in fully developed turbulent regimes. Third, we develop a TT algorithm to synthesize artificial snapshots that exhibit turbulent-like features, with a logarithmic cost in the mesh size. Our analysis demonstrates the ability of the TT representation to capture the characteristic features of turbulence. This offers a powerful quantum-inspired toolkit for the computational treatment of turbulent flows.
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https://arxiv.org/abs/2506.05477
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3cadc7dcefcbe618698c80c9d6cd96481be252ba412fa6b76d6252fbb0af3089
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2026-01-21T00:00:00-05:00
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A unified neural background-error covariance model for midlatitude and tropical atmospheric data assimilation
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arXiv:2506.11968v3 Announce Type: replace Abstract: Estimating background-error covariances remains a core challenge in variational data assimilation (DA). Operational systems typically approximate these covariances by transformations that separate geostrophically balanced components from unbalanced inertio-gravity modes - an approach well-suited for the midlatitudes but less applicable in the tropics, where different physical balances prevail. This study estimates background-error covariances in a reduced-dimension latent space learned by a neural-network autoencoder (AE). The AE was trained using 40 years of ERA5 reanalysis data, enabling it to capture flow-dependent atmospheric balances from a diverse set of weather states. We demonstrate that performing DA in the latent space yields analysis increments that preserve multivariate horizontal and vertical physical balances in both tropical and midlatitude atmosphere. Assimilating a single 500 hPa geopotential height observation in the midlatitudes produces increments consistent with geostrophic and thermal wind balance, while assimilating a total column water vapor observation with a positive departure in the nearly-saturated tropical atmosphere generates an increment resembling the tropical response to (latent) heat-induced perturbations. The resulting increments are localized and flow-dependent, and shaped by orography and land-sea contrasts. Forecasts initialized from these analyses exhibit realistic weather evolution, including the excitation of an eastward-propagating Kelvin wave in the tropics. Finally, we explore the transition from using synthetic ensembles and a climatology-based background error covariance matrix to an operational ensemble of data assimilations. Despite significant compression-induced variance loss in some variables, latent-space assimilation produces balanced, flow-dependent increments - highlighting its potential for ensemble-based latent-space 4D-Var.
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https://arxiv.org/abs/2506.11968
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39bf58e3f801f647868b1813ec1c2f13d9ed8c0e5b602d12dc448b236feb71e1
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2026-01-21T00:00:00-05:00
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Hierarchical Finite-Element Analysis of Multiscale Electromagnetic Problems via Sparse Operator-Adapted Wavelet Decomposition
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arXiv:2507.17989v2 Announce Type: replace Abstract: In this paper, we present a finite element method (FEM) framework enhanced by an operator-adapted wavelet decomposition algorithm designed for the efficient analysis of multiscale electromagnetic problems. Usual adaptive FEM approaches, while capable of achieving the desired accuracy without requiring a complete re-meshing of the computational domain, inherently couple different resolution levels. This coupling requires recomputation of coarser-level solutions whenever finer details are added to improve accuracy, resulting in substantial computational overhead. Our proposed method addresses this issue by decoupling resolution levels. This feature enables independent computations at each scale that can be incorporated into the solutions to improve accuracy whenever needed, without requiring re-computation of coarser-level solutions. The main algorithm is hierarchical, constructing solutions from finest to coarser levels through a series of sparse matrix-vector multiplications. Due to its sparse nature, the overall computational complexity of the algorithm is nearly linear. Moreover, Krylov subspace iterative solvers are employed to solve the final linear equations, with ILU preconditioners that enhance solver convergence and maintain overall computational efficiency. The numerical experiments presented in this article verify the high precision and nearly linear computational complexity of the proposed algorithm.
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https://arxiv.org/abs/2507.17989
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25ac03f9a6852f0aa33cf7ee2ccb3069b84555690e3b7db756094a65b3842ab5
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2026-01-21T00:00:00-05:00
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Cumulative Fidelity of LMT Clock Atom Interferometers in the Presence of Laser Noise
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arXiv:2508.10288v2 Announce Type: replace Abstract: Clock atom interferometry is an emerging technique in precision measurements that is particularly well suited for sensitivity enhancement through large momentum transfer (LMT). While current systems have demonstrated momentum separations of several hundreds of photon momenta, next-generation quantum sensors are targeting an LMT enhancement factor beyond $10^4$. However, the viability of LMT clock interferometers has recently come into question due to the potential impact of laser frequency noise. Here, we resolve this concern by analyzing the cumulative fidelity of sequential state inversions in an LMT atom interferometer. We show that the population error from $n$ pulses applied from alternating directions scales linearly with $n$. This is a significant advantage over the $n^2$ scaling that occurs when probing a two-level system $n$ times from the same direction. We further show that contributions to the interferometer signal from parasitic paths generated by imperfect pulses are negligible, for any loss mechanism. These results establish that laser frequency noise is not a practical limitation for the development of high-fidelity LMT clock atom interferometers.
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https://arxiv.org/abs/2508.10288
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4cbac4a1b71e356d0f029f0b598b2654a455610391a699f1c5d2d8ba02d79ab2
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2026-01-21T00:00:00-05:00
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Circularly polarized light scattering imaging of a cancerous layer creeping under a healthy layer for the diagnosis of early-stage cervical cancer
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arXiv:2508.13686v2 Announce Type: replace Abstract: Significance: Cervical cancer progresses through cervical intraepithelial neoplasia (CIN), which are precursor lesions of cervical cancer. In low-grade CIN, atypical cells generate inside the squamous epithelium, which causes the accuracy of cytodiagnosis for cervical cancer not to be very high. The grade of CIN can be estimated by the depth of atypical cell infiltration from the basal layer to the surface, rather than the abnormality of cells. Therefore, a non-invasive method is required to evaluate the depths of abnormal cells hidden at depths. Aim: Cancerous tissues beneath healthy tissues were experimentally identified by using circularly polarized light scattering (CiPLS). This method enabled the changes in the size of the cell nuclei within the penetration depth in tissue to be investigated. Approach: Artificial unexposed cancerous tissues were prepared that consisted of healthy/cancerous/healthy layers with various thicknesses of the topmost healthy layer and the cancerous layer. A polarization imaging camera with a quarter-wave plate was used to create distribution images of the circular polarization of the scattered light. Results: CiPLS images indicated that the thickness variation of the top healthy layer (the depth of the cancerous layer) caused significant changes in the degree of circular polarization. Conclusions: The depth of unexposed cancer lying within the optical penetration depth can be evaluated using a circular polarization imaging system based on the CiPLS method. These findings will lead to the development of a non-invasive optical diagnostic method for early-stage cervical cancer, potentially improving early detection and treatment outcomes.
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https://arxiv.org/abs/2508.13686
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881360bb297b20cf0258d071a9f2dd0de0c0b3ceedf8949635b2624026648a46
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2026-01-21T00:00:00-05:00
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Retroreflective surface optimisation for optical cavities with custom mirror profiles
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arXiv:2508.14712v2 Announce Type: replace Abstract: Coupling an emitter to a Fabry-P\'{e}rot optical cavity can provide a coherent and strong light-matter interface whose performance in a variety of applications depends critically on the emitter-photon coupling strength. Altering the typically spherical profiles of the cavity mirrors can improve this coupling strength, but directly optimising the mirror shape is numerically challenging as the multidimensional parameter space features many local optima. Here, we develop a two-step method to optimise mirror surface profiles while avoiding these issues. First, we optimise the target cavity eigenmode for the chosen application directly, and second, we construct the mirror surfaces to retroreflect this optimised target mode at both ends of the cavity. We apply our procedure to different emitter-cavity coupling scenarios. We show that mirror shaping can increase the cooperativity of coupling to a central emitter by a factor of approximately 3 across a wide range of geometries, and that, for coupling two or more emitters to a single cavity mode, the improvement factors can far exceed an order of magnitude.
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https://arxiv.org/abs/2508.14712
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a2bcbcf9a8cbcb420f058b4a77948a25ab89aaec981594c500d013f0a0a39b84
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2026-01-21T00:00:00-05:00
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Generalization vs. Memorization in Autoregressive Deep Learning: Or, Examining Temporal Decay of Gradient Coherence
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arXiv:2509.00024v2 Announce Type: replace Abstract: Foundation models trained as autoregressive PDE surrogates hold significant promise for accelerating scientific discovery through their capacity to both extrapolate beyond training regimes and efficiently adapt to downstream tasks despite a paucity of examples for fine-tuning. However, reliably achieving genuine generalization - a necessary capability for producing novel scientific insights and robustly performing during deployment - remains a critical challenge. Establishing whether or not these requirements are met demands evaluation metrics capable of clearly distinguishing genuine model generalization from mere memorization. We apply the influence function formalism to systematically characterize how autoregressive PDE surrogates assimilate and propagate information derived from diverse physical scenarios, revealing fundamental limitations of standard models and training routines in addition to providing actionable insights regarding the design of improved surrogates.
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https://arxiv.org/abs/2509.00024
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92ecb6555cd8dbbf105ff0c56f6ad719210bf6a9aeee77ef05264e671bfa7625
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2026-01-21T00:00:00-05:00
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Optically-Trapped Particle Tracking Velocimetry
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arXiv:2509.03676v3 Announce Type: replace Abstract: In this paper, we propose a microflow velocimetry based on particle tracking with the aid of optical trapping of tracers, namely, optically-trapped particle tracking velocimetry (ot-PTV). The ot-PTV has two phases: a trap phase, in which individual tracers are trapped by an optical force and held at a measurement position; a release phase, in which the tracer is released and advected by the fluid flow, without interference from the optical force. The released tracer is subsequently trapped again by the optical force. By repeating the set of trap and release phases, we can accumulate the sequential images of the tracer that have the same initial position. Although the data acquisition rate of ot-PTV is lower than that of standard micro-resolution particle image velocimetry ($\mu$PIV) due to the nature of pointwise measurement, an advantage of ot-PTV is that the measurement positions can be chosen by the experimenter. That is, even when tracers are scarce in a test section because of some external effects and/or the small size of the test section -- ill-suited cases for $\mu$PIV since the experimenter has to wait for tracers to diffuse into the test section (i.e., diffusion-limited situation) -- ot-PTV remains efficient. The concept of ot-PTV is validated using a benchmark experiment, i.e., a pressure-driven flow in a straight microchannel with a square cross-section. An application to thermally-induced microflows is also demonstrated, where tracers can be scarce in a test section due to thermophoresis.
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https://arxiv.org/abs/2509.03676
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58931bef6acec2a3dc09db5132b5d08fecfba94aea104057751e6802b49c197f
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2026-01-21T00:00:00-05:00
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Bridging mid and near infrared by combining optomechanics and self mixing
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arXiv:2509.11729v2 Announce Type: replace Abstract: This work describes a self-mixing-assisted optomechanical platform for transferring information between near- and mid-infrared radiation. In particular, the self-mixing signal of a mid-infrared quantum cascade laser is used to detect the oscillation of a membrane driven by light-induced forces exerted by a near-infrared excitation beam, which is amplitude-modulated at the membrane resonance frequency. This technique benefits from spectral broadness and, therefore, can link different spectral regions from both the excitation and probe sides. This versatility can pave the way for future applications of this self-mixing-assisted optomechanical platform in communication and advanced sensing systems.
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https://arxiv.org/abs/2509.11729
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e78ba69b8960e25ce63740462bb56e96f0dcc5be3739f1d3b53f527f12f3d5e8
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2026-01-21T00:00:00-05:00
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A Pathway to Sub-meV Detection of the Dark Universe: Robust Electron Avalanche in the PN junction at 10 mK
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arXiv:2509.11954v3 Announce Type: replace Abstract: The search for light dark matter and cosmic primordial neutrinos necessitates detectors with sub-millielectronvolt (sub-meV) energy thresholds. While superconducting quantum sensors have approached this sensitivity, they often face significant challenges regarding readout complexity and scalability. To address these limitations, we propose a hybrid Superconductor-Insulator-P-N (S-I-P-N) detector architecture. This concept combines the high sensitivity of superconducting Cooper pair breaking with the massive intrinsic gain of semiconductor electron avalanches. A critical prerequisite for this scheme is operation at millikelvin (mK) temperatures, raising the critical fundamental question of whether silicon PN junctions can sustain avalanche multiplication in a regime where carrier freeze-out is severe. Here, we experimentally validate the critical semiconductor amplification stage of the proposed detector. We demonstrate that Silicon Photomultipliers (SiPMs) retain robust Geiger-mode avalanche capabilities at 10 mK. We report a single-photoelectron gain of order 10$^6$ and a dark count rate as low as 5~mHz/mm$^2$, 7 orders of magnitude lower than at room temperature. These results confirm the viability of high-gain semiconductor readout in the deep cryogenic regime, clearing the primary obstacle regarding the semiconductor component for the realization of scalable, sub-meV threshold S-I-P-N detectors.
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https://arxiv.org/abs/2509.11954
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c81a009cae04f4759fc5032f4270f7713b16522804403d51acd87e5909d1cf44
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2026-01-21T00:00:00-05:00
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Multi-color XFEL pulses with variable color separation and time delay for multi-frame diffraction imaging
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arXiv:2509.14906v2 Announce Type: replace Abstract: X-ray free-electron lasers (XFELs) of high brightness have opened new opportunities for exploring ultrafast dynamical processes in matter, enabling imaging and movies of single molecules and particles at atomic resolution. In this paper, we present a straightforward method for multi-frame diffraction imaging, using the same electron beam to generate four-color XFEL pulses with adjustable wavelength separation and time delay. The optical klystron scheme is introduced to enhance FEL intensity and reduce the total length of undulators. The time delay is tuned via a magnetic chicane between the undulators with various colors. Using parameters of SHINE, start-to-end simulations demonstrate the effectiveness and tunability of our method, achieving representative results such as time delays of hundreds of femtoseconds and four-color XFEL pulses spanning 1.8 to 2.7 nm with 0.3 nm intervals. The proposed scheme enables the recording of multi-frame diffraction images in a single exposure, providing a new perspective for ultrafast molecular and atomic dynamics studies.
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https://arxiv.org/abs/2509.14906
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d3f84cae40140fb2e73f5a5b4068d3c97eabe5ee398f62cecf3557987f5c551c
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2026-01-21T00:00:00-05:00
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The Nature of Turbulence at Sub-Electron Scales in the Solar Wind
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arXiv:2509.17061v2 Announce Type: replace Abstract: The nature of turbulence at sub-electron scales has remained an open question, central to understanding how electrons are heated in the solar wind. This is primarily because spacecraft measurements have been limited to magnetic field fluctuations alone. We resolve this by deriving new high-resolution density fluctuations from spacecraft potential measurements of Parker Solar Probe resolving scales smaller than the electron gyro-radius ($\rho_e$). A systematic comparison of the density and magnetic spectra shows that both steepen near the electron scales. Notably, the density spectrum exhibits slopes close to $-10/3$, while the magnetic spectrum becomes consistently steeper than the density spectrum at scales smaller than $\rho_e$, indicating that the turbulence becomes electrostatic. These results are consistent with theoretical predictions of an electron entropy cascade, which may explain the irreversible dissipation of turbulent energy at sub-$\rho_e$ scales. The magnetic spectrum, however, is not as steep as expected for the electron entropy cascade, which may be due to limited signal-to-noise ratio and the presence of weakly damped electromagnetic fluctuations near $\rho_e$.
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https://arxiv.org/abs/2509.17061
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192d9a869d3a973c9e409498d0a5abfa2f64aa9892c36861363c0af1da707dbf
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2026-01-21T00:00:00-05:00
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Anderson self-localization of light in pair plasmas
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arXiv:2509.20594v2 Announce Type: replace Abstract: We demonstrate that in pair plasma weakly nonlinear electromagnetic waves, $a_0 \leq 1$, experience Anderson self-localization. The beat between the driver and a back-scattered wave creates charge-neutral, large random density fluctuations $\delta n/n_0 \gg 1$, and corresponding fluctuations of the dielectric permittivity $\epsilon$ (random plasma density grating). Propagating in quasi-1D, waves in a medium with spatially random self-created fluctuations of dielectric permeability experience localization. {In the linear regime, the instability can be classified as Induced Brillouin Scattering; it is described by the parameter $\rho _L = \left( a_0 { \omega_{p}/ }{\omega}\right)^{2/3} \leq 1 $, related to the Pierce parameter of Free Electron Lasers. In the cold case, the growth rate is $\Gamma \approx \rho _{L} \omega$ ($a_0 $ is laser nonlinearity parameter, $\omega_p$ is plasma frequency, $\omega$ is the laser frequency). } Anderson self-localization of light leads to (i) reflection of EM waves by the under-dense pair plasma; (ii) a wave already present inside the plasma separates into bright trapped pockets and dark regions. Mild initial thermal spread with $\Theta \equiv k_B T/(m_e c^2) \approx a_0^2$, restores wave propagation by suppressing the seeds of parametrically unstable density fluctuations. A circularly polarized driver produces linearly polarized structures, with position angle varying randomly between the bright pulses. Time-variability of the resulting density structures does not suppress localization due to remaining corrections (not white noise). We discuss possible applications to astrophysical Fast Radio Bursts.
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https://arxiv.org/abs/2509.20594
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5dc2b3bcac1a300ccfbcdd9be9828d5efc38016c8777637ae30c6758ab9f2299
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2026-01-21T00:00:00-05:00
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Automating Sensor Characterization with Bayesian Optimization
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arXiv:2509.21661v2 Announce Type: replace Abstract: The development of novel instrumentation requires an iterative cycle with three stages: design, prototyping, and testing. Recent advancements in simulation and nanofabrication techniques have significantly accelerated the design and prototyping phases. Nonetheless, detector characterization continues to be a major bottleneck in device development. During the testing phase, a significant time investment is required to characterize the device in different operating conditions and find optimal operating parameters. The total effort spent on characterization and parameter optimization can occupy a year or more of an expert's time. In this work, we present a novel technique for automated sensor characterization that aims to accelerate the testing stage of the development cycle. This technique leverages closed-loop Bayesian optimization (BO), using real-time measurements to guide parameter selection and identify optimal operating states. We demonstrate the method with a novel low-noise CCD, showing that the machine learning-driven tool can efficiently characterize and optimize operation of the sensor in a couple of days without supervision of a device expert.
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https://arxiv.org/abs/2509.21661
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0d33624a97c523e0def257501180a9f792ee87e65f393f43dbfa178b4d3497c3
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2026-01-21T00:00:00-05:00
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Data-Augmented Resolvent Analysis of Wall-Bounded High-Pressure Transcritical Flow
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arXiv:2509.25398v2 Announce Type: replace Abstract: High-pressure transcritical fluid flows are central to modern energy and propulsion systems. A key challenge arises in confined configurations, where optimizing performance requires a detailed understanding of the coupled hydrodynamic and thermodynamic nonlinearities governing these flows. In this context, low-order decomposition techniques, particularly resolvent analysis, provide an interpretable linear input-output framework to identify and quantify dominant amplification mechanisms of coherent flow structures. This work pursues two main objectives: (i) to establish a resolvent-based framework tailored to high-pressure transcritical fluid flows, and (ii) to characterize the spatio-temporal sensitivity of the resolvent operator using data-driven turbulent base flows. These analyses identify flow responses and forcings that optimally enhance mixing and heat transfer, along with their characteristic scales. Results show that amplification is dominated by streamwise-elongated structures with spanwise periodicity, associated with peak singular values at normalized spanwise wavenumbers of order unity. Unlike ideal-gas or incompressible flows, the dominant forcings originate from thermodynamic fluctuations in the pseudo-boiling region. Linearization about the turbulent mean flow yields intensified responses in the form of coherent counter-rotating vortex pairs. Energetic-scale motions are constrained by the low-Reynolds-number and non-isothermal conditions considered, with a dominant spectral mode reaching streamwise lengths comparable to instantaneous structures. Data-driven analyses further reveal coherent motions propagating at phase speeds absent from classical incompressible wall-bounded turbulence, intensified near the pseudo-boiling region and constrained toward the hot wall.
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https://arxiv.org/abs/2509.25398
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f766f2c790da9e0afc4c46049232c9bc5fbf70922d541315d125ef05bfb83d8d
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2026-01-21T00:00:00-05:00
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Consistent kinetic modeling of compressible flows with variable Prandtl numbers: Double-distribution quasi-equilibrium approach
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arXiv:2510.04197v2 Announce Type: replace Abstract: A consistent kinetic modeling and discretization strategy for compressible flows across all Prandtl numbers and specific heat ratios is developed using the quasi-equilibrium approach within two of the most widely used double-distribution frameworks. The methodology ensures accurate recovery of the Navier-Stokes-Fourier equations, including all macroscopic moments and dissipation rates, through detailed hydrodynamic limit analysis and careful construction of equilibrium and quasi-equilibrium attractors. Discretization is performed using high-order velocity lattices with a static reference frame in a discrete velocity Boltzmann context to isolate key modeling aspects such as the necessary requirements on expansion and quadrature orders. The proposed models demonstrate high accuracy, numerical stability and Galilean invariance across a wide range of Mach numbers and temperature ratios. Separate tests for strict conservation and measurements of all dissipation rates confirm these insights for all Prandtl numbers and specific heat ratios. Simulations of a thermal Couette flow and a sensitive two-dimensional shock-vortex interaction excellently reproduce viscous Navier-Stokes-Fourier-level physics. The proposed models establish an accurate, efficient and scalable framework for kinetic simulations of compressible flows with moderate supersonic speeds and discontinuities at arbitrary Prandtl numbers and specific heat ratios, offering a valuable tool for studying complex problems in fluid dynamics and paving the way for future extensions to the lattice Boltzmann context, by application of correction terms, as well as high-Mach and hypersonic regimes, employing target-designed reference frames.
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https://arxiv.org/abs/2510.04197
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81994fd5cb7267a1e434d06e998e4898e9f27d97bb062e7b0f5ec57dd5e47a22
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2026-01-21T00:00:00-05:00
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Finite elements and moving asymptotes accelerate quantum optimal control -- FEMMA
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arXiv:2510.04798v2 Announce Type: replace Abstract: Quantum optimal control is central to designing spin manipulation pulses. Gradient-based pulse optimization can be facilitated by either accelerating gradient evaluation or enhancing the convergence rate. In this work, we accelerated single-spin optimal control by combining the finite element method with the method of moving asymptotes. By treating discretized time as spatial coordinates, the Liouville - von Neumann equation was reformulated as a linear system, efficiently yielding a joint solution of the spin trajectory and control gradient. The method of moving asymptotes, relying on the ensemble fidelities and gradients, achieves rapid convergence for a target fidelity of 0.995.
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https://arxiv.org/abs/2510.04798
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c478ccdcbe8f01ea096b4f4eba7c81e0c7b38ad7e88109ddad6f62d46beb12bb
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2026-01-21T00:00:00-05:00
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Unveiling spin-orbital angular momentum locking in photonic Dirac vortex cavities
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arXiv:2510.13507v2 Announce Type: replace Abstract: Dirac vortices, originally studied in quantum field theories to predict localized zero-energy modes, were recently realized in photonics, leading to Dirac vortex cavities. With topological protection, Dirac vortex cavities offer robust single-mode large-area localized modes appealing for high-performance micro-lasers and other applications. As a spectrally-isolated single mode, the radiation of a Dirac vortex cavity mode was believed as having vanishing orbital angular momentum due to time-reversal symmetry. Here, we report the direct observation of orbital angular momentum radiation of a Dirac vortex cavity through spin-resolved measurements. Remarkably, we confirm the spin-orbital angular momentum locking in such radiation due to the spin-valley locking and inter-valley couplings. We demonstrate that the spin-orbital angular momentum locking is controlled by the chirality of the Kekul\'e modulation and propose design schemes for arbitrary-order single-mode OAM radiation.
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https://arxiv.org/abs/2510.13507
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ea04f2d226b475bd5d6019f4b6ca6cfd1a2a842609443ebb63f31d4164be870e
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2026-01-21T00:00:00-05:00
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Lattice-induced sound trapping in biperiodic metasurfaces of acoustic resonators
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arXiv:2510.17750v4 Announce Type: replace Abstract: A referential example of a physical system that supports bound states in the continuum (BICs) with an infinite quality factor ($Q$ factor) is a metasurface of discrete scatterers (resonators), whose response can be significantly modified by exploiting lattice interactions. In this work, we explore the multipole-interference mechanism for realizing accidental acoustic BICs (trapped modes) at $\Gamma$-point (in-plane Bloch wave vector $\mathbf{k}_{\parallel} = \mathbf{0}$) of biperiodic metasurfaces of acoustic resonators with one resonator per unit cell. To do so, we expand the pressure field from the metasurface into a series of scalar zonal ($m = 0$) spherical multipoles, carried by a normally incident plane wave, and formulate analytical conditions on the resonator multipole moments under which an eigenmode becomes a BIC. The conditions enable us to determine the lattice constant and frequency values that facilitate the formation of an axisymmetric BIC with a specific parity, resulting from destructive interference between zonal multipoles of the same parity, despite each moment radiating individually. By employing the T-matrix method for acoustic metasurfaces, we numerically investigate the BIC resonance in various structures, including finite arrays, and also the transformation of such resonances into high-$Q$ quasi-BIC regimes, which can be excited by a plane wave at normal incidence.
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https://arxiv.org/abs/2510.17750
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05d7994b996e5bfe3cb73ac5315e2c1d6462681003b0cfa4d83ad2406ad99c8b
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2026-01-21T00:00:00-05:00
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Carrier envelope phase and laser pulse shape effects on Schwinger vacuum pair production in super-Gaussian asymmetric electric fields
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arXiv:2510.17856v2 Announce Type: replace Abstract: We investigate the combined effects of carrier envelope phase and laser pulse shape on electron-positron pair production in the presence of an external asymmetric super-Gaussian electric field by solving the quantum Vlasov equation. By varying the field asymmetry, the pulse shape from Gaussian to super-Gaussian, and the carrier envelope phase, we show the momentum distribution and the number density of created pairs to exhibit extreme sensitivity to these field characteristics. The effects are also qualitatively explained by analyzing the turning-point structures within the WKB formalism. We observed that multiphoton pair production dominates in the case of long falling-pulse asymmetry. For a short falling pulse with a flat-top super-Gaussian laser profile, pair production is further facilitated. For certain field parameters, we demonstrate that the number density can be enhanced by two to three orders of magnitude.
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https://arxiv.org/abs/2510.17856
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15d976722aff474ad8fc6ab572b92b0804c517227fd13900babed1050937be11
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2026-01-21T00:00:00-05:00
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Gauss Principle in Incompressible Flow: Unified Variational Perspective on Pressure and Projection
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arXiv:2510.22925v2 Announce Type: replace Abstract: Following recent work (Gonzalez and Taha 2022; Peters and Ormiston 2025), this manuscript clarifies what the Gauss-Appell principle determines in incompressible, inviscid flow and how it connects to classical projection methods. At a fixed time, freezing the velocity and varying only the material acceleration leads to minimization of a quadratic subject to acceleration-level constraints. First-order conditions yield a Poisson-Neumann problem for a reaction pressure whose gradient removes the non-solenoidal and wall-normal content of the provisional residual, i.e. the Leray-Hodge projection. Thus, Gauss-Appell enforces the instantaneous kinematic constraints and recovers Euler at the instant. In steady flows, this principle -- on its own -- cannot select circulation or stagnation points because these are properties of the velocity state, not the instantaneous acceleration correction. The principle only determines the reaction pressure for an already-specified velocity field. The impressed/reaction pressure bookkeeping can be supplemented with orthogonality conventions that separate prescribed conservative forcing (if any) from the reaction enforcing the constraints. This variational viewpoint also yields a simple computational diagnostic: the minimized Appellian equals a L-2 norm of the reaction-pressure gradient which vanishes for constraint-compatible updates and grows with the magnitude of divergence and wall-flux mismatch. The goal of this note is simply to lend more clarity to the application of the Gauss principle, and to connect it concretely to well known concepts including potential flow theory, recent variational approaches and projection algorithms.
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https://arxiv.org/abs/2510.22925
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f22258032d10de9bf33993a15d0573d8d2d6cec441e688d091ea3d5ccd580eb5
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2026-01-21T00:00:00-05:00
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Nonlocal van der Waals density functional made faster
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arXiv:2511.04169v2 Announce Type: replace Abstract: A simplification of the VV10 van der Waals density functional [J. Chem. Phys. 133, 244103 (2010)] is made by an approximation of the integrand of the six-dimentional integral in terms of a few products of three-dimensional density-like distributions and potential-like functions of the interelectronic distance only, opening the way for its straightforward computation by fast multipole methods. An even faster computational scheme for molecular systems is implemented where the density-like distributions are fitted by linear combinations of usual atom-centered basis functions of Gaussian type and the six-dimensional integral is then computed analytically, at a fraction of the overall cost of a typical calculation. The simplicity of the new approximation is commensurate with that of the original VV10 functional, and the same level of accuracy is seen in tests on molecules.
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https://arxiv.org/abs/2511.04169
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36f735a060cbbbf7c1488d5127d6cfc7b365d259e55d717c41dc6a6b6db05623
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2026-01-21T00:00:00-05:00
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The Use of O2 in Gas Mixtures for Drift Chambers
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arXiv:2511.07082v2 Announce Type: replace Abstract: The use of Oxygen in gas mixtures for drift chambers is highly discouraged because Oxygen, being strongly electronegative, is generally believed to lead, even in very small quantities, to extremely reduced drift electron survival probability, thus preventing the detector's operation.The drift chamber of the MEG II experiment at PSI has been operating for several years with a gas mixture that mainly contains He:Isobutane in relative proportions of 90:10% by molar concentration, in addition to 1.5% Isopropanol and 0.5% Oxygen. Oxygen and Isopropanol are essential for the proper functioning of the chamber. The electron attachment in the mixture used has proven negligible for the proper operation of the chamber and agrees well with the Garfield++ simulation after correctly accounting for the three-body attachment simulation.
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https://arxiv.org/abs/2511.07082
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869f195e401033bca82da19caa23e278777cad9d67d058bcfd06bc81c970fe1d
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2026-01-21T00:00:00-05:00
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Comparative evaluation of future collider options
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arXiv:2511.20417v2 Announce Type: replace Abstract: In anticipation of the completion of the High-Luminosity Large Hadron Collider (HL-LHC) programme by the end of 2041, CERN is preparing to launch a new major facility in the mid-2040s. According to the 2020 update of the European Strategy for Particle Physics (ESPP), the highest-priority next collider is an electron-positron Higgs factory, followed in the longer term by a hadron-hadron collider at the highest achievable energy. The CERN directorate established a Future Colliders Comparative Evaluation working group in June 2023. This group brings together project leaders and domain experts to conduct a consistent evaluation of the Future Circular Collider (FCC) and alternative scenarios based on shared assumptions and standardized criteria. This report presents a comparative evaluation of proposed future collider projects submitted as input for the Update of the European Strategy for Particle Physics. These proposals are compared considering main performance parameters, environmental impact and sustainability, technical maturity, cost of construction and operation, required human resources, and realistic implementation timelines. An overview of the international collider projects within a similar timeframe, notably the CEPC in China and the ILC in Japan is also presented, as well as a short review of the status and prospects of new accelerator techniques.
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https://arxiv.org/abs/2511.20417
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78ecb5e8190cce820c9de984329b7a685d9e30e3dfbedf04ee66ea876c802769
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2026-01-21T00:00:00-05:00
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Drift towards isotropization during the 3D hydrodynamic turbulence onset
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arXiv:2512.04665v3 Announce Type: replace Abstract: The incompressible three-dimensional Euler equations develop very thin pancake-like regions of exponentially increasing vorticity. The characteristic thickness of such regions decreases exponentially with time, while the other two dimensions do not change considerably, making the flow near each pancake strongly anisotropic. The pancakes emerge in increasing number with time, which may enhance the anisotropy of the flow, especially if they orient similarly in space. In the present paper, we study numerically the anisotropy by analyzing the evolution of the so-called isotropy markers [Phys. Rev. Fluids 10, L022602 (2025)]. We show that these functions drift slowly towards unity, indicating the process of slow isotropization, which takes place without the viscous scales getting exited and despite the similar orientation of the emerging pancakes.
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https://arxiv.org/abs/2512.04665
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fcf249544ba0ab92ee1aa30829cbfaf1c57813642ab4e6dc24118fb1ed6a2390
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2026-01-21T00:00:00-05:00
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Design and Performance of a 96-channel Resistive PICOSEC Micromegas Detector for ENUBET
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arXiv:2512.05589v2 Announce Type: replace Abstract: The PICOSEC-Micromegas (PICOSEC-MM) detector is a fast gaseous detector that achieves picosecond-level timing by coupling a Cherenkov radiator, typically an MgF2 crystal, to a Micromegas-based photodetector with a photocathode. This configuration allows the fast photoelectron-induced signal to suppress the intrinsic time jitter of gaseous detectors, enabling sub-20 ps timing precision while preserving the robustness and scalability of micro-pattern gaseous detector technologies. The 96-pad PICOSEC-MM detector is a large-area demonstrator optimized for precision timing in high-energy physics, building on research and development insights from earlier 7-pad resistive prototypes to validate scalability, uniformity, and robustness for the ENUBET project. It employs a 2.5 nm diamond-like carbon photocathode and a Micromegas board with a surface resistivity of 10 megaohms per square, and was characterized using 150 GeV/c muons at the CERN SPS beamline, with one-third of the active area instrumented per run. A dedicated alignment procedure for multi-pad PICOSEC-MM systems was used to reconstruct pad centers and merge measurements across regions, yielding a timing resolution of 43 ps and uniform signal arrival time distributions over the tested area. Mechanical flatness was identified as a key factor, with planarity tolerances within 10 micrometers required to maintain good timing resolution, and the successful operation of the 96-pad demonstrator confirms the scalability of the PICOSEC-MM concept toward robust, high-granularity, picosecond-level gaseous timing detectors for monitored neutrino beam experiments such as ENUBET.
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https://arxiv.org/abs/2512.05589
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9338ea706ad5b024fe7d09ad6bb559e9bb67ff6945c2c6f1cbb456c02723d69a
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2026-01-21T00:00:00-05:00
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Zero- to low-field J-spectroscopy with a diamond magnetometer
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arXiv:2512.05776v2 Announce Type: replace Abstract: We report measurements of zero- to ultra-low-field nuclear magnetic resonance (ZULF NMR) signals at frequencies of a few hertz with a diamond-based magnetic sensor. The sensing diamond is a truncated pyramid with 0.18 mm height and a 0.5 mm x 0.5mm base. The minimum stand-off distance is < 1 mm, and the sensor sensitivity is 13 pT/(Hz)^(1/2) at frequencies f above 5 Hz with 1/f-like behavior at lower frequencies. NMR signals were generated via signal amplification by reversible exchange (SABRE) parahydrogen-based hyperpolarization resulting in zero-field signals at 1.7 Hz and 3.4 Hz corresponding to the expected hetero-nuclear J-coupling pattern of acetonitrile. This work demonstrates a magnet-free platform for detecting chemically specific NMR signals at ultra-low frequencies paving the way for portable noninvasive diagnostics in microscopic sample volumes for biomedicine, industrial sensing through metal enclosures, and field-deployable quantum analytical devices.
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https://arxiv.org/abs/2512.05776
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2128e500db73512356180d68d48374bcbe1949a26b2afa2c2cea50552fed2432
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2026-01-21T00:00:00-05:00
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Metasurface-based Terahertz Three-dimensional Holography Enabled by Physics-Informed Neural Network
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arXiv:2601.01221v2 Announce Type: replace Abstract: Artificial intelligence, an emerging, powerful and efficient computational tool, has played a crucial role in the design of optical devices. For the design of holographic metasurfaces, traditional algorithms require multiple iterations between the metasurface and target planes, resulting in excessive computation time. Here, a physics-informed neural network (PINN) is proposed for the fast design of terahertz three-dimensional (3D) holographic metasurfaces. Trained in a self-supervised manner, the PINN eliminates the need for paired input-label datasets. After training, the PINN enables end-to-end mapping between the target holographic patterns and metasurface structures. Both simulation and experimental results of single-plane and 3D multi-plane holography demonstrate that metasurfaces designed by PINN offer higher imaging quality than traditional iterative algorithms. Moreover, the PINN can find approximate solutions of metasurface structures even in physically counterintuitive scenarios, where the holographic patterns of two parallel imaging planes are completely distinct. Furthermore, the inference process of PINN typically takes less than 1 second, much faster than the traditional algorithms requiring iterative computation. Notably, the PINN simultaneously accounts for both phase and amplitude modulation, thereby outperforming traditional phase-only modulation algorithms in handling complex physical scenarios and offering superior imaging quality. This end-to-end design approach has the potential to pave the way for the realization of high-quality, real-time, and large-scale terahertz 3D holographic display technology.
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https://arxiv.org/abs/2601.01221
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5b9fdbe43949afd16b7b405525891e306715dfba65e41ec4566be051a5b5be72
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2026-01-21T00:00:00-05:00
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Possible Vulnerability of Bell-Clauser-Horne-Shimony-Holt Tests used for Quantum Certification
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arXiv:2601.07867v2 Announce Type: replace Abstract: A hidden variables (HVs) model is reported, which reproduces quantum predictions for Bell-Clauser-Horne-Shimony-Holt (Bell-CHSH) tests. The existence of such a model poses some limitations to quantum certifications that rely on Bell-CHSH inequality violations. The reported model does not prove wrong Bell's theorem. The latter assumes the factorability of the probability density $p_{AB}$, which rules the stochastic behavior of the HVs. The reported HVs model is based on an extended form of $p_{AB}$, which is suggested by Lebesgue's decomposition theorem for bounded functions. The considered $p_{AB}$ complies with locality and realism, and also with measurement independence, parameter independence and outcome independence.
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https://arxiv.org/abs/2601.07867
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ecaa4f9b70c2791006c45a9ac2bc39fcc393c69b7710b1d1dfd05a65efd71a6a
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2026-01-21T00:00:00-05:00
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Light-induced spin-polarized desorption of Rb atoms from Co surfaces
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arXiv:2601.08442v2 Announce Type: replace Abstract: The spin polarization of Rb atoms undergoing light-induced desorption from a spin-polarized Co (110) surface was investigated. Desorption induced by pulsed UV-light irradiation was driven by a non-thermal mechanism and the spins of the desorbed Rb atoms were polarized. This implies spin transfer between the surface and the adsorbate during desorption.
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https://arxiv.org/abs/2601.08442
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30342960d985505b0ff18bdf29a380eb8f7143aff7ae33029131d28df2a913b9
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2026-01-21T00:00:00-05:00
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Information-Thermodynamic Analysis of the DNA--RNA Polymerase Complex via Interface Dissipation: Based on Observer--Observed Swap Symmetry
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arXiv:2601.08577v2 Announce Type: replace Abstract: RNA polymerase (RNAP) elongates RNA by walking along a DNA template and selectively incorporating ribonucleoside triphosphates (rNTPs). Rather than mechanically replicating the base sequence, RNAP conditions binding and chemistry on the currently read template nucleotide, converting sequence dependence into a bias in its stochastic motion. Thermal fluctuations generate forward/backward translocation attempts; cognate rNTP binding and incorporation stabilize the forward register and suppress backward return, yielding net advance via a Brownian-ratchet mechanism. We formulate the DNA--RNAP complex as a bipartite stochastic system, separating template-side degrees of freedom $X$ from RNAP-side response degrees of freedom $Y$. Irreversibility is quantified by a Kullback--Leibler divergence between forward and time-reversed path measures, yielding joint and marginal dissipations. From these we define an exchange-invariant interface dissipation $\Sigma_{\mathrm{int}}$ that isolates time-reversal asymmetry generated specifically by coupling across the DNA--RNAP interface. We prove an exchange-symmetric second law, $\Sigma_{\mathrm{int}}\ge 0$, and show that this interface measure is well defined without invoking local detailed balance. To connect the framework to data analysis, we present a minimal continuous-time Markov jump model implementing the Brownian-ratchet logic and a likelihood-ratio protocol to estimate dissipation rates from discretely sampled trajectories. Finite-sample convergence is assessed via Markov-order diagnostics, clarifying bias--variance tradeoffs under coarse-graining. The interface-centered measure provides a consistent basis for comparing energetic cost across regimes (sequence-dependent kinetics, misincorporation, backtracking, proofreading) and can be combined with hidden-state inference when internal states are partially observed.
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https://arxiv.org/abs/2601.08577
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d3686644dd2725186e5ba33151ec869dcee23055306b6394f925071b39547e24
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2026-01-21T00:00:00-05:00
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IEPDYN: Integral-equation formalism of population dynamics
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arXiv:2601.09187v2 Announce Type: replace Abstract: We propose the integral-equation formalism of population dynamics (IEPDYN) to describe the population dynamics of distinct configurational states. According to classical reaction dynamics theory, the probability density associated with a given state obeys the Liouville equation, including influx from and efflux to neighboring states. By introducing a Markov approximation for the crossing of boundaries separating the states, tractable integral equations governing the state populations are derived. Once the time-dependent quantities appearing in these equations are evaluated, the population dynamics on long timescales can be obtained. Because these quantities depend only on a few states in the local neighborhood of a given state, they can be computed using a set of short-timescale molecular dynamics (MD) simulations. The IEPDYN method is formulated in continuous time and therefore does not rely on a coarse-grained timescale (lag time). Consequently, kinetic quantities obtained from IEPDYN are free from lag-time dependence, which has been discussed as a limitation in other approaches. We apply the IEPDYN method to the binding and unbinding kinetics of CH$_4$/CH$_4$, Na$^+$/Cl$^-$, and 18-crown-6-ether (crown ether)/K$^+$ in water. For both kinetics, the time constants estimated from the IEPDYN method are almost comparable to those obtained from brute-force MD simulations. The required timescale of each MD trajectory in the IEPDYN method is approximately two orders of magnitude shorter than that in the brute-force MD approach in the crown ether/K$^+$ system. This reduction in the trajectory timescale enables applications to complex binding and unbinding systems whose characteristic timescales are far beyond those directly accessible by brute-force MD simulations.
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https://arxiv.org/abs/2601.09187
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b47760cb060a86e3ca17a1287db39513bc8cba75bc548832ef5452113b50e3dc
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2026-01-21T00:00:00-05:00
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A Neutron Microscope Using a Nested Wolter-I Condenser and a Bank of Diffractive-Refractive Achromatic Objectives
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arXiv:2601.10829v2 Announce Type: replace Abstract: We propose a nested Wolter-I mirror design for a neutron condenser, which is based on established X-ray telescope technology. We demonstrate through simulations that it can increase the flux density at the ESS imaging instrument ODIN by up to two orders of magnitude. Experimental measurements of reflectivity and figure errors on a prototype mirror element confirm the technical feasibility of the approach. Then, we discuss design strategies for an imaging objective to fully exploit the condenser specifications while achieving spatial resolutions comparable to those of X-ray micro-CT instruments. Analytically, we show that for monochromatic beams suitable solutions exist employing arrays of hundreds of identical objectives, realized either as compound refractive lenses (CRLs) or Fresnel zone plates (FZPs). To mitigate the inherent chromatic aberration of these optics, each individual objective could be replaced by an achromatic FZP/CRL combination. Key optical properties of the resulting microscope are estimated. This novel full-field microscopy concept for highly divergent, polychromatic neutron beams has the potential to improve temporal and spatial resolution for large samples and sample environments and to enable the simultaneous acquisition of hundreds of projections in neutron tomography.
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https://arxiv.org/abs/2601.10829
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Academic Papers
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31bcabf97e3b3fbfa934e60c91467529a971fdb7e01b72b78b693d1709045feb
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2026-01-21T00:00:00-05:00
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Matrix-product-state-based band-Lanczos solver for quantum cluster approaches
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arXiv:2310.10799v2 Announce Type: replace-cross Abstract: We present matrix-product state (MPS) based band Lanczos method as solver for quantum cluster methods such as the variational cluster approximation. While a na\"ive implementation of MPS as cluster solver would barely improve its range of applicability, we show that our approach makes it possible to treat cluster geometries well beyond the reach of exact diagonalization methods. The key modifications we introduce are a continuous energy truncation combined with a convergence criterion that is more robust against approximation errors introduced by the MPS representation and provides a bound to deviations in the resulting Green's function. The potential of the resulting cluster solver is demonstrated by computing the self-energy functional for the single-band Hubbard model at half filling in the strongly correlated regime, on different cluster geometries. Here, we find that only when treating large cluster sizes, observables can be extrapolated to the thermodynamic limit, which we demonstrate at the example of the staggered magnetization. Treating clusters sizes with up to $6\times 6$ sites we obtain significant improvement over the extrapolation accessible with exact diagonalization solvers when comparing to quantum Monte Carlo results. Finally, we illustrate the applicability of the MPS cluster solver to more complex models by calculating spectral properties as relevant for the electron-doped cuprate CaCuO$_2$.
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https://arxiv.org/abs/2310.10799
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Academic Papers
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e248692d731e2a32d7506f4c98e7419ea5eea02b7c92b3b3f1d9514013184c1d
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2026-01-21T00:00:00-05:00
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Light-enhanced nonlinear Hall effect
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arXiv:2401.18038v5 Announce Type: replace-cross Abstract: It is well known that a nontrivial Chern number results in quantized Hall conductance. What is less known is that, generically, the Hall response can be dramatically different from its quantized value in materials with broken inversion symmetry. This stems from the leading Hall contribution beyond the linear order, known as the Berry curvature dipole (BCD). While the BCD is in principle always present, it is typically very small outside of a narrow window close to a topological transition and is thus experimentally elusive without careful tuning of external fields, temperature, or impurities. In this work, we transcend this challenge by devising optical driving and quench protocols that enable practical and direct access to large BCD and nonlinear Hall responses. Varying the amplitude of an incident circularly polarized laser drives a topological transition between normal and Chern insulator phases, and importantly allows the precise unlocking of nonlinear Hall currents comparable to or larger than the linear Hall contributions. This strong BCD engineering is even more versatile with our two-parameter quench protocol, as demonstrated in our experimental proposal. Our predictions are expected to hold qualitatively across a broad range of Hall materials, thereby paving the way for the controlled engineering of nonlinear electronic properties in diverse media.
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https://arxiv.org/abs/2401.18038
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Academic Papers
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0c1231f34d9891291679693c6670c5f5ccb30ec46b000e45d8c8a02d55b731b8
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2026-01-21T00:00:00-05:00
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High-precision and low-depth quantum algorithm design for eigenstate problems
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arXiv:2406.04307v2 Announce Type: replace-cross Abstract: Estimating the eigenstate properties of quantum systems is a long-standing, challenging problem for both classical and quantum computing. Existing universal quantum algorithms typically rely on ideal and efficient query models (e.g. time evolution operator or block encoding of the Hamiltonian), which, however, become suboptimal for actual implementation at the quantum circuit level. Here, we present a full-stack design of quantum algorithms for estimating the eigenenergy and eigenstate properties, which can achieve high precision and good scaling with system size. The gate complexity per circuit for estimating generic Hamiltonians' eigenstate properties is $\tilde{O} (\log \varepsilon^{-1})$, which has a logarithmic dependence on the inverse precision $\varepsilon$. For lattice Hamiltonians, the circuit depth of our design achieves near-optimal system-size scaling, even with local qubit connectivity. Our full-stack algorithm has low overhead in circuit compilation, which thus results in a small actual gate count (CNOT and non-Clifford gates) for lattice and molecular problems compared to advanced eigenstate algorithms. The algorithm is implemented on IBM quantum devices using up to 2,000 two-qubit gates and 20,000 single-qubit gates, and achieves high-precision eigenenergy estimation for Heisenberg-type Hamiltonians, demonstrating its noise robustness.
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https://arxiv.org/abs/2406.04307
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Academic Papers
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812cfc1db17324d668d520522b64f090d08aeac0f1b4f6bd1ab775d9d822254d
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2026-01-21T00:00:00-05:00
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Anomalous quantized nonlinear Thouless pumping
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arXiv:2409.19515v2 Announce Type: replace-cross Abstract: It has recently been theoretically predicted and experimentally observed that a soliton resulting from nonlinearity can be pumped across an integer or fractional number of unit cells as a system parameter is slowly varied over a pump period. Nonlinear Thouless pumping is now understood as the flow of instantaneous Wannier functions, ruling out the possibility of pumping a soliton across a nonzero number of unit cells over one cycle when a corresponding Wannier function does not exhibit any flow, i.e., when the corresponding Bloch band that the soliton bifurcates from is topologically trivial. Here we surprisingly find an anomalous nonlinear Thouless pump where the displacement of a soliton over one cycle differs from the Chern number of the Bloch band from which the soliton comes. We develop a general theory showing that this anomalous behavior arises from a transition of a soliton between different Wannier functions by passing through an intersite-soliton (or dipole-soliton) state. Furthermore, we find a nonlinearity-induced integer quantized Thouless pump of a soliton, allowing a soliton to travel across one unit cell during a pump period, even when the corresponding band is topologically trivial. Our results open the door to studying nonlinearity-induced Thouless pumping of solitons.
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https://arxiv.org/abs/2409.19515
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Academic Papers
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3ece3c8ebc368477ecf51b923d897e5a6c97e859db26020045fde669dabcd004
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2026-01-21T00:00:00-05:00
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Typical Quantum States of the Universe are Observationally Indistinguishable
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arXiv:2410.16860v3 Announce Type: replace-cross Abstract: We establish three impossibility results regarding our knowledge of the quantum state of the universe. Suppose the universal quantum state is a typical unit vector in a high-dimensional subspace $\mathscr{H}_0$ of Hilbert space $\mathscr{H}$, such as the low-entropy subspace defined by the Past Hypothesis. We show that: (1) Any particular observation is incapable of identifying the universal state vector in $\mathscr{H}_0$ or substantially reducing the set of possibilities. In other words, the overwhelming majority of possible state vectors are observationally indistinguishable from each other. (2) For any reasonably probable measurement outcome and for most pairs of vectors in $\mathscr{H}_0$, that outcome will not appreciably favor one vector over the other. (3) Bayesian updating on any measurement result, unless it is extraordinarily improbable, has a negligible effect on the initial uniform probability distribution over the states in $\mathscr{H}_0$. These findings represent the most stringent epistemic constraints known for a quantum universe and are derived from a typicality theorem in quantum statistical mechanics. We close by considering how theoretical considerations beyond empirical evidence might inform our understanding of this fact and our knowledge of the universal quantum state.
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https://arxiv.org/abs/2410.16860
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Academic Papers
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9814bff337a9e4e551288da8d5663ab095712bf190d5b52b32e5510c29561a6d
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2026-01-21T00:00:00-05:00
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An Adaptive Online Smoother with Closed-Form Solutions and Information-Theoretic Lag Selection for Conditional Gaussian Nonlinear Systems
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arXiv:2411.05870v2 Announce Type: replace-cross Abstract: Data assimilation (DA) combines partial observations with dynamical models to improve state estimation. Filter-based DA uses only past and present data and is the prerequisite for real-time forecasts. Smoother-based DA exploits both past and future observations. It aims to fill in missing data, provide more accurate estimations, and develop high-quality datasets. However, the standard smoothing procedure requires using all historical state estimations, which is storage-demanding, especially for high-dimensional systems. This paper develops an adaptive-lag online smoother for a large class of complex dynamical systems with strong nonlinear and non-Gaussian features, which has important applications to many real-world problems. The adaptive lag allows the utilization of observations only within a nearby window, thus reducing computational complexity and storage needs. Online lag adjustment is essential for tackling turbulent systems, where temporal autocorrelation varies significantly over time due to intermittency, extreme events, and nonlinearity. Based on the uncertainty reduction in the estimated state, an information criterion is developed to systematically determine the adaptive lag. Notably, the mathematical structure of these systems facilitates the use of closed analytic formulae to calculate the online smoother and adaptive lag, avoiding empirical tunings as in ensemble-based DA methods. The adaptive online smoother is applied to studying three important scientific problems. First, it helps detect online causal relationships between state variables. Second, the advantage of reduced computational storage expenditure is illustrated via Lagrangian DA, a high-dimensional nonlinear problem. Finally, the adaptive smoother advances online parameter estimation with partial observations, emphasizing the role of the observed extreme events in accelerating convergence.
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https://arxiv.org/abs/2411.05870
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Academic Papers
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40063558dcdbb818eb432b4e139a79713680cfdc7c16c38855e972a292a68a78
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2026-01-21T00:00:00-05:00
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Riemannian Denoising Model for Molecular Structure Optimization with Chemical Accuracy
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arXiv:2411.19769v2 Announce Type: replace-cross Abstract: We introduce a framework for molecular structure optimization using denoising model on a physics-informed Riemannian manifold (R-DM). Unlike conventional approaches operating in Euclidean space, our method leverages a Riemannian metric that better aligns with molecular energy change, enabling more robust modeling of potential energy surfaces. By incorporating internal coordinates reflective of energetic properties, R-DM achieves chemical accuracy with an energy error below 1 kcal/mol. Comparative evaluations on QM9, QM7-X, and GEOM datasets demonstrate improvements in both structural and energetic accuracy, surpassing conventional Euclidean-based denoising models. This approach highlights the potential of physics-informed coordinates for tackling complex molecular optimization problems, with implications for tasks in computational chemistry and materials science.
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https://arxiv.org/abs/2411.19769
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Academic Papers
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cb43176194a7a9f59ae377bba810368db9142cf0efbaf0085c9d53714db9529b
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2026-01-21T00:00:00-05:00
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Addressing general measurements in quantum Monte Carlo
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arXiv:2412.01384v4 Announce Type: replace-cross Abstract: Quantum Monte Carlo is one of the most promising approaches for dealing with large-scale quantum many-body systems. It has played an extremely important role in understanding strongly correlated physics. However, two fundamental problems, namely the sign problem and general measurement issues, have seriously hampered its scope of application. We propose a universal scheme to tackle the problems of general measurement. The target observables are expressed as the ratio of two types of partition functions $\langle \mathrm{O} \rangle=\bar{Z}/Z$, where $\bar{Z}=\mathrm{tr} (\mathrm{Oe^{-\beta H}})$ and $Z=\mathrm{tr} (\mathrm{e^{-\beta H}})$. These two partition functions can be estimated separately within the reweight-annealing frame, and then be connected by an easily solvable reference point. We have successfully applied this scheme to XXZ model and transverse field Ising model, from 1D to 2D systems, from two-body to multi-body correlations and even non-local disorder operators, and from equal-time to imaginary-time correlations. The reweighting path is not limited to physical parameters, but also works for space and time. Essentially, this scheme solves the long-standing problem of calculating the overlap between different distribution functions in mathematical statistics, which can be widely used in statistical problems, such as quantum many-body computation, big data and machine learning.
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https://arxiv.org/abs/2412.01384
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Academic Papers
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79332ffc550463e152e875167cd788d336be797a88a3cbb6d5c7f3c2012331b0
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2026-01-21T00:00:00-05:00
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Recurrent convolutional neural networks for modeling non-adiabatic dynamics of quantum-classical systems
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arXiv:2412.06631v3 Announce Type: replace-cross Abstract: Recurrent neural networks (RNNs) have recently been extensively applied to model the time-evolution in fluid dynamics, weather predictions, and even chaotic systems thanks to their ability to capture temporal dependencies and sequential patterns in data. Here we present a RNN model based on convolution neural networks for modeling the nonlinear non-adiabatic dynamics of hybrid quantum-classical systems. The dynamical evolution of the hybrid systems is governed by equations of motion for classical degrees of freedom and von Neumann equation for electrons. The physics-aware recurrent convolution (PARC) neural network structure incorporates a differentiator-integrator architecture that inductively models the spatiotemporal dynamics of generic physical systems. We apply our RNN approach to learn the space-time evolution of a one-dimensional semi-classical Holstein model after an interaction quench. For shallow quenches (small changes in electron-lattice coupling), the deterministic dynamics can be accurately captured using a single-CNN-based recurrent network. In contrast, deep quenches induce chaotic evolution, making long-term trajectory prediction significantly more challenging. Nonetheless, we demonstrate that the PARC-CNN architecture can effectively learn the statistical climate of the Holstein model under deep-quench conditions.
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https://arxiv.org/abs/2412.06631
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Academic Papers
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1141ac09419de1c6c68564450728d4adba4eaff58bf6017e3cda1fddf8742254
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2026-01-21T00:00:00-05:00
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Machine Learning Symmetry Discovery for Integrable Hamiltonian Dynamics
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arXiv:2412.14632v2 Announce Type: replace-cross Abstract: We propose a data-driven Machine-Learning Symmetry Discovery (MLSD) framework for identifying continuous symmetry generators and their Lie-algebraic structure directly from phase-space trajectory data expressed in canonical coordinates. MLSD parameterizes candidate conserved quantities with neural networks and learns antisymmetric structure coefficients by enforcing Poisson-bracket closure, supplemented by a weak independence regularizer. We validate MLSD on two integrable benchmark systems -- the three-dimensional Kepler problem and the three-dimensional isotropic harmonic oscillator -- recovering the expected non-Abelian algebras (respectively $\mathfrak{so}(4)$ and $\mathfrak{su}(3)$) up to basis transformations. This work focuses on integrable benchmark dynamics, where global conserved quantities are well-defined and admit compact representations learnable from canonical-coordinate trajectories. Extending symmetry discovery to mixed or chaotic phase-space regimes is an important direction for future work.
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https://arxiv.org/abs/2412.14632
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Academic Papers
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b7fb606a609ae1ab8c3390d55831b8470b1625dc46e73353920a9e8190058785
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2026-01-21T00:00:00-05:00
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Tensorization of neural networks for improved privacy and interpretability
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arXiv:2501.06300v3 Announce Type: replace-cross Abstract: We present a tensorization algorithm for constructing tensor train/matrix product state (MPS) representations of functions, drawing on sketching and cross interpolation ideas. The method only requires black-box access to the target function and a small set of sample points defining the domain of interest. Thus, it is particularly well-suited for machine learning models, where the domain of interest is naturally defined by the training dataset. We show that this approach can be used to enhance the privacy and interpretability of neural network models. Specifically, we apply our decomposition to (i) obfuscate neural networks whose parameters encode patterns tied to the training data distribution, and (ii) estimate topological phases of matter that are easily accessible from the MPS representation. Additionally, we show that this tensorization can serve as an efficient initialization method for optimizing MPS in general settings, and that, for model compression, our algorithm achieves a superior trade-off between memory and time complexity compared to conventional tensorization methods of neural networks.
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https://arxiv.org/abs/2501.06300
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Academic Papers
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db123cf89f1551203cc81c66d4ee1637243fdca68d6fef40a6a8229738bb754d
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2026-01-21T00:00:00-05:00
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Decoherence of Schr\"odinger cat states in light of wave/particle duality
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arXiv:2501.12328v3 Announce Type: replace-cross Abstract: We challenge the standard picture of decohering Schr\"odinger cat states as an ensemble average obeying a Lindblad master equation, brought about locally from an irreversible interaction with an environment. We generate self-consistent collections of pure system states correlated with specific environmental records, corresponding to the function of the wave-particle correlator first introduced in Carmichael et al. [Phys. Rev. Lett. 85, 1855 (2000)]. In the spirit of Carmichael et al. [Coherent States: Past, Present and Future, pp. 75-91, World Scientific (1994)], we find that the complementary unravelings evince a pronounced disparity when the ``position'' and ``momentum'' of the damped cavity mode - an explicitly open quantum system - are measured. Intensity-field correlations may largely deviate from a monotonic decay, while Wigner functions of the cavity state display contrasting manifestations of quantum interference when conditioned on photon counts sampling a continuous photocurrent. In turn, the conditional photodetection events mark the contextual diffusion of both the net charge generated at the homodyne detector, and the electromagnetic field amplitude in the resonator.
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https://arxiv.org/abs/2501.12328
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Academic Papers
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dc6299aa2fc025a24f7068446458040fe247839477713eb0520d52867cb17e31
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2026-01-21T00:00:00-05:00
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Exceptional-Point-Induced Nonequilibrium Entanglement Dynamics in Bosonic Networks
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arXiv:2502.04639v2 Announce Type: replace-cross Abstract: Exceptional points (EPs), arising in non-Hermitian systems, have garnered significant attention in recent years, enabling advancements in sensing, wave manipulation, and mode selectivity. However, their role in quantum systems, particularly in influencing quantum correlations, remains underexplored. In this work, we investigate how EPs control multimode entanglement in bosonic chains. Using a Bogoliubov-de Gennes (BdG) framework to describe the Heisenberg equations, we identify EPs of varying orders and uncover spectral transitions between purely real, purely imaginary, and mixed eigenvalue spectra. These spectral regions, divided by EPs, correspond to three distinct entanglement dynamics: oscillatory, exponential, and hybrid. Remarkably, we demonstrate that higher-order EPs, realized by non-integer-pi hopping phases or nonuniform interaction strengths, significantly enhance the degree of multimode entanglement compared to second-order EPs. Our findings provide a pathway to leveraging EPs for entanglement control and exhibit the potential of non-Hermitian physics in advancing quantum technologies.
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https://arxiv.org/abs/2502.04639
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Academic Papers
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d0cc212559499477a2d4de3d6f6eeea34e177656403d5b28d1c2fa1a6de2560d
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2026-01-21T00:00:00-05:00
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Modeling and Simulation of Open Membranes in Stokes Flow with Mixed-Dimensional Coupling
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arXiv:2504.16823v2 Announce Type: replace-cross Abstract: In this work, we present a mathematical and computational framework to model the dynamics of open lipid bilayer membranes interacting with ambient Stokes flow. The model explicitly couples the three-dimensional viscous fluid, the two-dimensional membrane surface, and its one-dimensional free edge. We develop an axisymmetric hybrid BEM-FEM method that solves the problem with an effective one-dimensional formulation. A key component is a local mesh refinement strategy designed to accurately resolve singularities and boundary layers originating at the membrane edge. Several numerical examples are provided to showcase its ability to capture intricate edge dynamics and multiscale fluid-membrane coupling.
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https://arxiv.org/abs/2504.16823
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Academic Papers
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6cc8d812b9aaf61325f2991dcbf54a26ff71954793182b959c997b9ebf28861f
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2026-01-21T00:00:00-05:00
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$\mathcal{P}$, $\mathcal{T}$-violating axion-mediated interactions in RaOH molecule
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arXiv:2505.08667v3 Announce Type: replace-cross Abstract: If axion simultaneously has the scalar couplings to the nucleons and pseudo-scalar couplings to the electrons, it may mediate a $\mathcal{P}$, $\mathcal{T}$-violating interaction between the electronic shell and nuclei in the molecules. The polyatomic molecule RaOH, which is considered as a promising platform for the $\mathcal{P}$, $\mathcal{T}$ violation searches, is studied for its sensitivity to such interactions. Due to the long-range nature (on molecular scales) of the axion-mediated interaction, it is important whether the enhancement parameter would be sensitive to the vibration of the molecule. Our results imply that the impact of the vibrations on the axion-mediated electron-nucleon interaction in the molecule is similar to the impact on the short-range electron-nucleon scalar-pseudoscalar interaction studied earlier.
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https://arxiv.org/abs/2505.08667
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Academic Papers
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647450ef3c9151fb83e4e17b41b97bbd421185ffe8e50bd096026cc53ca24dc9
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2026-01-21T00:00:00-05:00
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Tunable spin-phonon polarons in a chiral molecular qubit framework
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arXiv:2506.04885v2 Announce Type: replace-cross Abstract: Chiral structures that produce asymmetric spin-phonon coupling can theoretically generate spin-phonon polarons -- quasiparticles exhibiting non-degenerate spin states with phonon displacements. These quasiparticles are speculated to be the origin of chirality-induced spin selectivity and presumably can display exotic dynamic behaviors. However, direct experimental evidence of spin-phonon polarons has been lacking. Using a chiral molecular qubit framework embedding stable semiquinone-like radicals, we report spin dynamic signatures that indicate the formation of spin-phonon polarons for the first time. Our non-adiabatic model reveals that these quasiparticles introduce an active spin relaxation channel when polaron reorganization energy approaches Zeeman splitting. This new channel manifests itself as anomalous, temperature-independent spin relaxation, which can be suppressed by high magnetic fields or pore-filling solvents (e.g. CH2Cl2, CS2). Such field- and guest-tunable relaxation is unattainable in conventional spin systems. Harnessing this mechanism could boost repetition rates in spin-based quantum information technologies without compromising coherence or quantum sensing performance.
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https://arxiv.org/abs/2506.04885
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Academic Papers
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fd8b72ab5789a4661285ba93411df5a35c1c5ed77f08f94a056e30e92a95bbde
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2026-01-21T00:00:00-05:00
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Evolution of a twisted electron wave packet perturbed by an inhomogeneous electric field
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arXiv:2506.06548v3 Announce Type: replace-cross Abstract: Laguerre-Gaussian (LG) wave packets, known for their vortex structure and nonzero orbital angular momentum (OAM), are of great interest in various scientific fields. Here we study the nonrelativistic dynamics of a spatially-localized electron LG wave packet interacting with an inhomogeneous external electric field that violates the axial symmetry of the initial wave function. We focus on the analysis of the electron density and demonstrate how it is affected by the external field. Within the first order of perturbation theory, we calculate the electron wave function and reveal that the electric field may significantly alter the wave packet's structure and distort its qualitative form. We demonstrate that due to the interaction with the external field, the degenerate zeros of the initial wave function located on the $z$ axis split into multiple nondegenerate nodes in the transverse plane representing separate single-charge vortices. This mechanism resembles the analogous effects known in topological optics. These findings provide new insights into controlling and manipulating twisted matter beams and into their possible instabilities.
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https://arxiv.org/abs/2506.06548
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Academic Papers
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