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4e04f9a6ada0b861f406e22d41c8aef11abd76646aa5cdfef61703ffbdfd1656
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2026-01-07T00:00:00-05:00
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Hydrodynamic Whispering: Enabling Near-Field Silent Communication via Artificial Lateral Line Arrays
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arXiv:2601.02394v1 Announce Type: cross Abstract: To address the imperative for covert underwater swarm coordination, this paper introduces "Hydrodynamic Whispering," a near-field silent communication paradigm utilizing Artificial Lateral Line (ALL) arrays. Grounded in potential flow theory, we model the transmitter as an oscillating dipole source. The resulting pressure field exhibits steep nearfield attenuation (scaling with 1/r^2, naturally delimiting a secure "communication bubble" with intrinsic Low Probability of Interception (LPI) properties. We propose a transceiver architecture featuring a Binary Phase Shift Keying (BPSK) modulation scheme adapted for mechanical actuator inertia, coupled with a bio-inspired 24-sensor conformal array. To mitigate low Signal-to-Noise Ratio (SNR) in turbulent environments,a Spatio-Temporal Joint Processing framework incorporating Spatial Matched-Field Beamforming is developed. Simulation results demonstrate that the system achieves an array gain of approximately 13.8 dB and maintains a near-zero Bit Error Rate (BER) within the effective range. This study validates the feasibility of utilizing localized hydrodynamic pressure fluctuations for reliable and secure short-range underwater networking.
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https://arxiv.org/abs/2601.02394
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Academic Papers
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93f2ee64a45952835296b80eea9f3c124731424cd95ebf5a6e6cbcf7bb2ecd40
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2026-01-07T00:00:00-05:00
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How Alice, long before her time, derived the principles of quantum mechanics
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arXiv:2601.02419v1 Announce Type: cross Abstract: This philosophical dialogue explores the idea that the foundational principles of quantum mechanics need not be interpreted as describing a new physics, but may instead arise from the logical necessity of formalising the act of measurement within a coherent algebraic framework. By pushing this perspective to its extreme, the dialogue argues that the core structures of quantum mechanics can be derived independently of any specifically quantum properties of atomic particles, and can be formulated within an otherwise classical theory once limitations of observability and measurement context are taken seriously.
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https://arxiv.org/abs/2601.02419
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Academic Papers
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621255ec4728b17b6aec98dbdd2908b0f7bae63743492846f277bc1339368c1f
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2026-01-07T00:00:00-05:00
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Thrust Regulation in a Solid Fuel Ramjet using Dynamic Mode Adaptive Control
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arXiv:2601.02429v1 Announce Type: cross Abstract: This paper presents the application of a novel data-driven adaptive control technique, called dynamic mode adaptive control (DMAC), for regulating thrust in a solid fuel ramjet (SFRJ). A high-fidelity computational model incorporating compressible flow theory and equilibrium chemistry is used to simulate the combustion dynamics. An adaptive tracking controller is designed using the DMAC framework, which leverages dynamic mode decomposition to approximate the local system behavior, followed by a tracking controller synthesized around the identified model. Simulation results demonstrate that DMAC provides an effective and reliable approach for thrust regulation in SFRJs. In addition, a systematic hyperparameter sensitivity study is conducted by varying the tuning parameters over several orders of magnitude. The resulting responses show that the closed-loop performance and tracking error remain stable across wide parameter variations, indicating that DMAC exhibits strong robustness to hyper parameter tuning.
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https://arxiv.org/abs/2601.02429
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Academic Papers
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e8bab59a2fd4f661527d5b63e121b571291aceac96ca3996bbe0f059ed075de8
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2026-01-07T00:00:00-05:00
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Anomalous Collision of Exceptional Points on Nonorientable Manifolds
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arXiv:2601.02442v1 Announce Type: cross Abstract: Band degeneracies, ranging from Hermitian Dirac points to non-Hermitian exceptional points (EPs), play a central role in topological phase transitions. Beyond the topology of individual degeneracies, their mutual interactions yield richer phenomena. A representative example is the anomalous non-annihilating collision of pairwise-created degeneracies, previously believed to occur only in non-Abelian multiband systems. Here, we theoretically reveal and experimentally demonstrate that such an anomalous collision can emerge even in a simple two-band system without non-Abelian nature. In a two-dimensional non-Hermitian lattice whose Brillouin zone forms a nonorientable Klein bottle, two EPs with opposite topological charges, pairwise created from a hybrid point, merge into a new vortex point upon re-encounter, instead of annihilating. Remarkably, the hybrid point is a defective degeneracy featuring no eigenenergy braiding, whereas the vortex point is a non-defective degeneracy yet exhibits nontrivial eigenenergy braiding. This process manifests a non-Hermitian phase transition from a gapped phase to a gapless phase, a scenario that we directly observe in a hybrid-dimensional acoustic lattice via momentum-resolved band braid and Berry phase measurements. Our findings identify nonorientability as a new arena for engineering band degeneracies and topological phases, and pave the way for experimentally exploring the interplay between exceptional and nonorientable topology.
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https://arxiv.org/abs/2601.02442
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Academic Papers
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b845d3cdccb0936a8588068c967e50b5528a36e5b02f117c117df301116c9e9f
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2026-01-07T00:00:00-05:00
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Magnetic reconnection with a 0.1 rate: Effective resistivity in general relativistic magnetohydrodynamics
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arXiv:2601.02460v1 Announce Type: cross Abstract: Relativistic magnetic reconnection is thought to power various multi-wavelength emission signatures from neutron stars and black holes. Relativistic resistive magnetohydrodynamics (RRMHD) offers the simplest model of reconnection. However, a small uniform resistivity underestimates the reconnection rate compared to first-principles kinetic models. By employing an effective resistivity based on kinetic models - which connects the reconnection electric field to the charge-starved current density - we show that RRMHD can reproduce the increased reconnection rate of kinetic models, both in local current sheets and in global black hole magnetospheres.
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https://arxiv.org/abs/2601.02460
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Academic Papers
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c34ad4610323750ee64521e90d447ca38e219b2e7c2ba18f7c722265d6f5df9c
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2026-01-07T00:00:00-05:00
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Resonances in b-EMRIs: playing the black hole piano
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arXiv:2601.02468v1 Announce Type: cross Abstract: Stellar-mass binaries evolving in the vicinity of supermassive black holes (SMBHs) may be common in the universe, either in active galactic nuclei or in other astrophysical environments. Here, we study in detail the resonant excitation of SMBH modes driven by a nearby stellar-mass binary. The resulting resonant energy fluxes vary with the orbital location and frequency of the binary, exhibiting a rich and complex structure. In particular, we find that the total energy flux radiated to infinity is maximized at a gravitational-wave frequency that is close to, but not exactly equal to, the real part of the corresponding quasinormal-mode frequency. Moreover, as the binary is moved farther away from the SMBH, this offset from the mode frequency becomes increasingly pronounced. In addition, for suitable orientations, the binary can effectively ``feed'' the light ring of the SMBH, selectively exciting particular oscillation modes. For rotating (Kerr) black holes, the mode spectrum is significantly more intricate; however, individual modes are also less strongly damped, leading to an enhanced - but more difficult to interpret - resonant response.
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https://arxiv.org/abs/2601.02468
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Academic Papers
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e57d85cd6edfe6925ced0290594a3cf62373fe98cafef11f577f2df9aced5516
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2026-01-07T00:00:00-05:00
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Deep learning parameter estimation and quantum control of single molecule
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arXiv:2601.02517v1 Announce Type: cross Abstract: Coherent control, a central concept in physics and chemistry, has sparked significant interest due to its ability to fine-tune interference effects in atoms and individual molecules for applications ranging from light-harvesting complexes to molecular qubits. However, precise characterization of the system's dissipative dynamics is required for its implementation, especially at high temperature. In a quantum control experiment, this means learning system-bath parameters and driving coupling strengths. Here, we demonstrate how to infer key physical parameters of a single molecule driven by spectrally modulated pulses at room temperature. We develop and compare two computational approaches based on two-photon absorption photoluminescence signals: an optimization-based minimization scheme and a feed-forward neural network. The robustness of our approach highlights the importance of reliable parameter estimation in designing effective coherent control protocols. Our results have direct applications in ultrafast spectroscopy, quantum materials and technology.
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https://arxiv.org/abs/2601.02517
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Academic Papers
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2380a403951de2a99b7224f0fa3e8d3165747fb7d0e8e36d521dfb3cbe2800a9
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2026-01-07T00:00:00-05:00
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Fluids at an electrostatically active surface: Optimum in interfacial friction and electrohydrodynamic drag
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arXiv:2601.02539v1 Announce Type: cross Abstract: While fluids near a solid surface are at the core of applications in energy storage/conversion, electrochemistry/electrowetting and adsorption/catalysis, their nanoscale behavior remains only partially deciphered. Beyond conventional effects (e.g. adsorption/reaction, interfacial transport, phase transition shifts), recent experimental and theoretical studies on metallic surfaces have unraveled exotic peculiarities such as complex electrostatic screening, unexpected wetting transition, and interfacial quantum friction. These novel features require developing and embarking new tools to tackle the coupling between charge relaxation in the metal and molecular behavior in the vicinal fluid. Here, using the concept of Virtual Thomas-Fermi fluids, we employ a molecular simulation approach to investigate interfacial transport of fluid molecules and metal charge carriers at their interface--including the underlying electrostatically-driven dynamic friction and the coupling between charge current/hydrodynamic flow (the so-called electrohydrodynamic drag). While conventional numerical techniques consider either insulating materials or metallic materials described as polarizable, non-conducting media, our atom-scale strategy provides an effective yet realistic description of the solid excitation spectrum--including charge relaxation modes and conductivity. By applying this approach to water near metallic surfaces of various electrostatic screening lengths, we unveil a non-monotonous dependence of the fluid/solid friction on the metallicity with a maximum occurring as the charge dynamic structure factors of the solid and fluid strongly overlap. Moreover, we report a direct observation of the electrohydrodynamic drag which arises from the momentum transfer between the solid and liquid through dynamic electrostatic interactions and the underlying interfacial friction.
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https://arxiv.org/abs/2601.02539
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Academic Papers
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a9afdb2bacd441b6149ef39d2ee2f68765b353b8548a8047c623758d85e6c83d
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2026-01-07T00:00:00-05:00
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Optomechanical platform for high-frequency gravitational wave and vector dark matter detection
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arXiv:2601.02576v1 Announce Type: cross Abstract: We present a proposal for a nanomechanical membrane resonator integrated into a moderate-finesse ($\mathcal{F}\sim 10$) optical cavity as a versatile platform for detecting high-frequency gravitational waves and vector dark matter. Gravitational-wave sensitivity arises from cavity-length modulation, which resonantly drives membrane motion via the radiation-pressure force. This force also enables in situ tuning of the membrane's resonance frequency by nearly a factor of two, allowing a frequency coverage from 0.5 to 40 kHz using six membranes. The detector achieves a peak strain sensitivity of $2\times 10^{-23}/\sqrt{\text{Hz}}$ at 40 kHz. Using a silicon membrane positioned near a gallium-arsenide input mirror additionally provides sensitivity to vector dark matter via differential acceleration from their differing atomic-to-mass number ratios. The projected reach surpasses the existing limits in the range of $2\times 10^{-12}$ to $2\times 10^{-10}$ $\text{eV}/c^2$ for a one-year measurement. Consequently, the proposed detector offers a unified approach to searching for physics beyond the Standard Model, probing both high-frequency gravitational waves and vector dark matter.
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https://arxiv.org/abs/2601.02576
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471fd5f7711fead40460598b402132bbc32c1f38c68d00af574e476e33cc69ca
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2026-01-07T00:00:00-05:00
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Dynamic Synchronization of Driven Self-Oscillators: Modeling and Experiment
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arXiv:2601.02584v1 Announce Type: cross Abstract: Synchronization of self-sustained oscillators under fixed-frequency and amplitude forcing is well understood, but how time-varying forcing mangles phase locking has been much less explored. Theory predicts that slow, deterministic modulation of the drive amplitude or frequency can lead to a peculiar synchronization regime characterized by intermittent locking of the oscillation phase beyond the Arnold-tongue boundaries associated with fixed harmonic forcing. We test these predictions in a controllable aeroacoustic self oscillator, i.e, a whistle, that exhibits a robust limit cycle and is subject to external acoustic forcing with programmable frequency and amplitude modulation. Under both slowly varying frequency or amplitude of the forcing, three regimes are observed: (i) strict synchronization (ii) intermittent synchronization, characterized by alternating phase locking and brief phase slip episodes and (iii) no synchronization, with regular phase slips. Particularly in strict synchronization regime, the phase of the oscillator will follow arbitrary slowly-varying drive phase and under amplitude modulation its amplitude fluctuations are strongly suppressed.
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https://arxiv.org/abs/2601.02584
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Academic Papers
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4cafb12f78da83faf6f97f01070f5a34917fca22b68dc05af357c0fbaf376549
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2026-01-07T00:00:00-05:00
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Contact resistance and interfacial engineering: Advances in high-performance 2D-TMD based devices
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arXiv:2601.02628v1 Announce Type: cross Abstract: The development of advanced electronic devices is contingent upon sustainable material development and pioneering research breakthroughs. Traditional semiconductor-based electronic technology faces constraints in material thickness scaling and energy efficiency. Atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDs) have emerged as promising candidates for next-generation nanoelectronics and optoelectronic applications, boasting high electron mobility, mechanical strength, and a customizable band gap. Despite these merits, the Fermi level pinning effect introduces uncontrollable Schottky barriers at metal-2D-TMD contacts, challenging prediction through the Schottky-Mott rule. These barriers fundamentally lead to elevated contact resistance and limited current-delivery capability, impeding the enhancement of 2D-TMD transistor and integrated circuit properties. In this review, we succinctly outline the Fermi pinning effect mechanism and peculiar contact resistance behavior at metal/2D-TMD interfaces. Subsequently, highlights on the recent advances in overcoming contact resistance in 2D-TMDs devices, encompassing interface interaction and hybridization, van der Waals (vdW) contacts, prefabricated metal transfer and charge-transfer doping will be addressed. Finally, the discussion extends to challenges and offers insights into future developmental prospects.
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https://arxiv.org/abs/2601.02628
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Academic Papers
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3e6672820e5a81c12c0435d7b506b86d6bb74ad567121e464e76f31629f3e3ac
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2026-01-07T00:00:00-05:00
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Cellular wrapping of elastic particles by a supported lipid membrane
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arXiv:2601.02657v1 Announce Type: cross Abstract: Constancy of life vitally depends on the internalization of particles through biomembranes. Of particular interest, cellular uptake, including phagocytosis, receptor-mediated endocytosis, and membrane fusion, critically depends on the elasticity of particles. Cellular membranes are strongly linked to a supporting cytoskeleton. However, in most previous studies, the effect of this cortical network somehow is overlooked. In this paper, we study the cellular wrapping of a membrane around a 2D elastic particle in the presence of a substrate mimicking cytoskeleton. Our simulations show that the impact of particle flexibility on the wrapping process depends on the magnitude of the membrane particle adhesion. In contrast, the extent of membrane protrusions formed around the target always increases with target stiffness. Since the extension of membrane protrusions is an essential step in the phagocytosis process, this result may indicate a selective behavior of macrophages in the phagocytosis of aged red blood cells.
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https://arxiv.org/abs/2601.02657
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4b963e7144938bca99e6f086bfb22a3f9143707ccc5acb6647ac892145b1135e
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2026-01-07T00:00:00-05:00
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Stable boundary modes for fragile topology from spontaneous PT-symmetry breaking
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arXiv:2601.02672v1 Announce Type: cross Abstract: Two-dimensional topological insulators protected by nonlocal symmetries or with fragile topology usually do not admit robust in-gap edge modes due to the incompatibility between the symmetry and the boundary. Here, we show that in a parity-time (PT) symmetric system robust in-gap topological edge modes can be stably induced by non-Hermitian couplings that spontaneously break the PT symmetry of the eigenstates. The topological edge modes traverse the imaginary spectral gap between a pair of fragile topological bands, which is opened by the presence of the non-Hermitian perturbation. We demonstrate that the net number of resulting in-gap modes is protected by an operator version of anomaly cancellation that extends beyond the Hermitian limit. The results imply that loss and gain can in principle drive fragile topological phenomena to stable topological phenomena.
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https://arxiv.org/abs/2601.02672
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Academic Papers
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080dcd68c2f664ba0afa7d2cc4df7f45ce4b9643d01060b3650a111f7a6d6cc5
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2026-01-07T00:00:00-05:00
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The Future of Higgs Physics
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arXiv:2601.02729v1 Announce Type: cross Abstract: In this lecture, I discuss measurements of the properties of the Higgs boson and related observables in the era of Higgs factories. This highly motivated experimental program is the challenge for the next generation of particle physicists.
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https://arxiv.org/abs/2601.02729
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Academic Papers
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9e880d49c6866e92fd05858858a5a3cc6841038828b4c5e87fffe42b3f2ca19c
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2026-01-07T00:00:00-05:00
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SpaceWire-based Data Acquisition Network for the Solar Flare Sounding Rocket Experiment FOXSI-4 and FOXSI-5
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arXiv:2601.02788v1 Announce Type: cross Abstract: We developed a SpaceWire-based data acquisition (DAQ) system for the FOXSI-4 and FOXSI-5 sounding rocket experiments, which aim to observe solar flares with high sensitivity and dynamic range using direct X-ray focusing optics. The FOXSI-4 mission, launched on April 17, 2024, achieved the first direct focusing observation of a GOES M1.6 class solar flare with imaging spectroscopy capabilities in the soft and hard X-ray energy ranges, using a suite of advanced detectors, including two CMOS sensors, four CdTe double-sided strip detectors (CdTe-DSDs), and a Quad-Timepix3 detector. To accommodate the high photon flux from a solar flare and these diverse detector types, a modular DAQ network architecture was implemented based on SpaceWire and the Remote Memory Access Protocol (RMAP). This modular architecture enabled fast, reliable, and scalable communication among various onboard components, including detectors, readout boards, onboard computers, and telemetry systems. In addition, by standardizing the communication interface and modularizing each detector unit and its associated electronics, the architecture also supported distributed development among collaborating institutions, simplifying integration and reducing overall complexity. To realize this architecture, we developed FPGA-based readout boards (SPMU-001 and SPMU-002) that support SpaceWire communication for high-speed data transfer and flexible instrument control. In addition, a real-time ground support system was developed to handle telemetry and command operations during flight, enabling live monitoring and adaptive configuration of onboard instruments in response to the properties of the observed solar flare. The same architecture is being adopted for the upcoming FOXSI-5 mission, scheduled for launch in 2026.
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https://arxiv.org/abs/2601.02788
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Academic Papers
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a32f8104453fb6b35d5fae66e82485ba78a20909ec525975584af259fd5bb324
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2026-01-07T00:00:00-05:00
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Transformation Journey of Zr-based MOFs: Study on Mechanics and Hydrogen Storage under Doping Regulation
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arXiv:2601.02794v1 Announce Type: cross Abstract: This study delves into the transformation journey of Zr-based Metal-Organic Frameworks (MOFs), focusing on enhancing their mechanical properties and hydrogen storage capacities through doping regulation. MOFs, a versatile class of crystalline porous materials, have garnered significant attention due to their unique properties and broad potential applications in gas storage, separation, catalysis, and sensing. Among them, Zr-based MOFs stand out for their exceptional stability and high surface area. This research systematically investigates six key Zr-based MOFs (UIO-66, UIO-67, UIO-68, MOF-801, MOF-802, and MOF-841) using multiscale computational methods, including molecular dynamics (MD) simulations, grand canonical Monte Carlo (GCMC) simulations, and density functional theory (DFT). The study explores the impact of metal ion substitution (Fe, Co, Ni, Cu, Zn) on the mechanical and hydrogen storage properties of these MOFs. Our findings reveal that metal ion substitution significantly influences the mechanical stability and hydrogen adsorption capacity of Zr-based MOFs, providing valuable insights for the design and optimization of high-performance MOF materials.
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https://arxiv.org/abs/2601.02794
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Academic Papers
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e11fa334a576d6328135323ba0d23a161ce48e0a3db3b3425cbf08cc6e433afb
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2026-01-07T00:00:00-05:00
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Interplay of Structure and Dynamics in Solid Polymer Electrolytes: a Molecular Dynamics Study of LiPF6/polypropylene carbonate
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arXiv:2601.02869v1 Announce Type: cross Abstract: Solid-state batteries (SSB) are emerging as next-generation electrochemical energy storage devices. Achieving high energy density in SSB relies on solid polymer electrolytes (SPE) that are electrochemically stable against both lithium metal and high-potential positive electrodes, two conditions that are difficult to satisfy without chemical degradation. In this work, molecular dynamics simulations are employed to investigate the relationship between structure and dynamics in carbonate-based SPE composed of polypropylene carbonate and lithium hexafluorophosphate (LiPF$_6$), at salt concentrations ranging from 0.32 to 1.21 mol$/$kg. Structural properties are analyzed under ambient pressure at the experimentally relevant temperature $T = 353$ K. Since the slow dynamical processes governing ion transport in these systems are inaccessible to direct molecular dynamics, transport properties are simulated at elevated temperatures up to 900 K and extrapolated to $T = 353$ K using Arrhenius behavior. The results reveal strong ionic correlations, a limited fraction of free ions, and a predominance of negatively charged clusters, especially at high salt concentration. At high temperature, the self-diffusion coefficient of Li$^+$ exceeds that of PF$_6^-$ due to weaker Li$^+$-carbonate and ion-ion interactions. However, at $T = 353$ K, Li$^+$ mobility becomes lower than that of the anion, consistent with typical experimental observations in SPE. As expected, the ionic conductivity $\sigma$ increases with temperature, while at $T = 353$ K it exhibits a maximum for salt concentrations between 1.0 and 1.1 mol$/$kg. Overall, the estimated physico-chemical parameters highlight the key role of ion correlations in SPE and suggest strategies to optimize electrolyte performance. The Arrhenius extrapolation approach used here provides valuable insight into ion transport mechanisms in solid polymer electrolytes.
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https://arxiv.org/abs/2601.02869
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32ab648a65e5fa10de4625b3eb10e00fa2c6b21b1c0876ed0ebe27d9dc00f610
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2026-01-07T00:00:00-05:00
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Data-driven Reduction of Transfer Operators for Particle Clustering Dynamics
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arXiv:2601.02932v1 Announce Type: cross Abstract: We develop an operator-based framework to coarse-grain interacting particle systems that exhibit clustering dynamics. Starting from the particle-based transfer operator, we first construct a sequence of reduced representations: the operator is projected onto concentrations and then further reduced by representing the concentration dynamics on a geometric low-dimensional manifold and an adapted finite-state discretization. The resulting coarse-grained transfer operator is finally estimated from dynamical simulation data by inferring the transition probabilities between the Markov states. Applied to systems with multichromatic and Morse interaction potentials, the reduced model reproduces key features of the clustering process, including transitions between cluster configurations and the emergence of metastable states. Spectral analysis and transition-path analysis of the estimated operator reveal implied time scales and dominant transition pathways, providing an interpretable and efficient description of particle-clustering dynamics.
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https://arxiv.org/abs/2601.02932
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Academic Papers
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dd605a507147658895416e0d11584b95660147c9848c25238d039756df81ad0f
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2026-01-07T00:00:00-05:00
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DeepH-pack: A general-purpose neural network package for deep-learning electronic structure calculations
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arXiv:2601.02938v1 Announce Type: cross Abstract: In computational physics and materials science, first-principles methods, particularly density functional theory, have become central tools for electronic structure prediction and materials design. Recently, rapid advances in artificial intelligence (AI) have begun to reshape the research landscape, giving rise to the emerging field of deep-learning electronic structure calculations. Despite numerous pioneering studies, the field remains in its early stages; existing software implementations are often fragmented, lacking unified frameworks and standardized interfaces required for broad community adoption. Here we present DeepH-pack, a comprehensive and unified software package that integrates first-principles calculations with deep learning. By incorporating fundamental physical principles into neural-network design, such as the nearsightedness principle and the equivariance principle, DeepH-pack achieves robust cross-scale and cross-material generalizability. This allows models trained on small-scale structures to generalize to large-scale and previously unseen materials. The toolkit preserves first-principles accuracy while accelerating electronic structure calculations by several orders of magnitude, establishing an efficient and intelligent computational paradigm for large-scale materials simulation, high-throughput materials database construction, and AI-driven materials discovery.
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https://arxiv.org/abs/2601.02938
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dcb54340b563a02908d84fddfa823b7e9ee97ec0a01985d269c99108e58438d7
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2026-01-07T00:00:00-05:00
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Nonseparability as Time-Averaged Dynamic States
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arXiv:2601.02977v1 Announce Type: cross Abstract: Nonseparability - multipartite states that cannot be factorized - is one of the most striking features of quantum mechanics, as it gives rise to entanglement and non-causal correlations. In quantum computing, it also contributes directly to the computational advantage of quantum computers over its digital counterparts. In this work, we introduce a simple mechanism that frames nonseparability as a time-averaged manifestation of an underlying oscillatory process within state space. The central idea is the inclusion of auxiliary angular frequencies that modulate the temporal evolution of composite states. These additional dynamical degrees of freedom act as coherence channels through which nonseparability is mediated. While the proposed formalism could eventually serve as an alternative theoretical handle on the mechanisms of quantum entanglement, its greater significance lies in opening practical routes for simulating multipartite entanglement in controlled classical wave systems.
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https://arxiv.org/abs/2601.02977
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6423b8c6285f11131d20233282984b94adcd4656d1eb203009ab45bf5a779f97
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2026-01-07T00:00:00-05:00
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Shubnikov-de Haas oscillations of two-dimensional electron gases in AlYN/GaN and AlScN/GaN heterostructures
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arXiv:2601.03022v1 Announce Type: cross Abstract: AlYN and AlScN have recently emerged as promising nitride materials that can be integrated with GaN to form two-dimensional electron gases (2DEGs) at heterojunctions. Electron transport properties in these heterostructures have been enhanced through careful design and optimization of epitaxial growth conditions. In this work, we report for the first time Shubnikov-de Haas (SdH) oscillations of 2DEGs in AlYN/GaN and AlScN/GaN heterostructures, grown by metal-organic chemical vapor deposition. SdH oscillations provide direct access to key 2DEG parameters at the Fermi level: (1) carrier density, (2) electron effective mass (m* ~ 0.24 me for AlYN/GaN and m* ~ 0.25 me for AlScN/GaN), and (3) quantum scattering time (~ 68 fs for AlYN/GaN and ~ 70 fs for AlScN/GaN). These measurements of fundamental transport properties provide critical insights for advancing emerging nitride semiconductors for future high-frequency and power electronics.
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https://arxiv.org/abs/2601.03022
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eb43c44cad23eb7aaacf580c37305d720ae46a5b2574db123a3980946467b17d
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2026-01-07T00:00:00-05:00
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Charge transport in liquid-crystalline phthalocyanine-based thin-film transistors
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arXiv:2601.03058v1 Announce Type: cross Abstract: We investigate a series of liquid-crystalline phthalocyanines (metal-free and Cu, Zn, Ni, Co complexes) by correlating their vibrational signatures with their electronic performance in organic thin-film transistors (OTFTs). Raman spectroscopy reveals metal-dependent distortions of the phthalocyanine macrocycle, reflected in systematic shifts of the C-N-C and M-N vibrational modes. When integrated into OTFTs, all compounds exhibit markedly enhanced current response under ultrahigh vacuum compared to an N2-rich environment, demonstrating that intrinsic charge transport is strongly suppressed by atmospheric species. Temperature-dependent measurements (100-300 K) show clear threshold-voltage shifts driven by deep interface and bulk traps, while all devices display thermally activated mobility with low activation energies (14-20 meV). These results highlight how mesomorphic order, metal coordination, and environmental conditions collectively govern charge transport in liquid-crystalline phthalocyanines, offering design guidelines for their use as orientable semiconducting materials in organic electronics.
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https://arxiv.org/abs/2601.03058
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6ef8f8e55bac3711fe867ffd01e5386174f2472338bf4e7d1d7486915a26354b
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2026-01-07T00:00:00-05:00
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Forward self-similar solutions to the 2D Navier--Stokes equations
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arXiv:2601.03161v1 Announce Type: cross Abstract: We construct self-similar solutions to the 2D Navier--Stokes equations evolving from arbitrarily large $-1$--homogeneous initial data and present numerical evidence for their non-uniqueness.
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https://arxiv.org/abs/2601.03161
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b8963e7bc79ba3581a13f9576ef56612c94a66fbc25a268c422d12f83d0104bc
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2026-01-07T00:00:00-05:00
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Dynamical bicontinuous networks from 3D active phase separation
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arXiv:2601.03221v1 Announce Type: cross Abstract: We study phase separation between coexisting active and passive fluids in three-dimensions, using both numerical simulation and experiments. Chaotic flows of the active phase drive giant interfacial deformations and cause the co-existing phases to interpenetrate, generating a continuously reconfiguring bicontinuous steady-state morphology that persists over the lifetime of the active fluid. We demonstrate how activity controls the structure of the bicontinuous network. Quantitative analysis reveals the dominance of dynamical steady-state sheet-like interfaces, in marked difference from the transient bicontinuous structures observed in passive liquid-liquid phase separation, where saddle-like surfaces dominate. These results demonstrate how active stresses suppress the coarsening dynamics of conventional phase separation, generating steady-state reconfigurable morphologies not accessible with conventional surface-modifying agents or through quenching of transient phase separated structures.
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https://arxiv.org/abs/2601.03221
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be4cb2a874f5a22fe10d1d71a293fdbc20056f53e9c330f1a38ca77f1659b628
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2026-01-07T00:00:00-05:00
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Restoring Bloch's Theorem for Cavity Exciton Polaron-Polaritons
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arXiv:2601.03230v1 Announce Type: cross Abstract: We introduce a symmetry-informed representation for hybrid photon--exciton--phonon quantum electrodynamics Hamiltonians to restore Bloch's theorem. The interchange of momenta between fermions and bosons breaks crystalline excitons' translational symmetry under strong coupling. Restoring said symmetry, we efficiently compute experimentally accessible observables without introducing approximations to the Hamiltonian, enabling investigations that elucidate material properties in strong coupling with applications enhancing coherent transport and unlocking symmetry-forbidden matter transitions.
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https://arxiv.org/abs/2601.03230
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6ea932bf013bf3d5ba792ae626594ea6c290634bbd7b395ec078ce62afb0cac5
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2026-01-07T00:00:00-05:00
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Monitoring the daily variation of Sun-Earth magnetic fields using galactic cosmic rays
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arXiv:2410.09064v2 Announce Type: replace Abstract: The interplanetary magnetic field (IMF) between the Sun and Earth is an extension of the solar magnetic field carried by the solar wind into interplanetary space. Monitoring variations in the IMF upstream of the Earth would provide very important information for the prediction of space weather effects, such as effects of solar storms and the solar wind, on human activity. In this study, the IMF between the Sun and Earth was measured daily for the first time using a cosmic-ray observatory. Cosmic rays mainly consist of charged particles that are deflected as they pass through a magnetic field.Therefore, the cosmic-ray Sun shadow, caused by high-energy charged cosmic rays blocked by the Sun and deflected by the magnetic field, can be used to explore the transverse IMF between the Sun and Earth. By employing the powerful kilometer-square array at the Large High Altitude Air Shower Observatory, the cosmic-ray Sun shadows were observed daily with high significance for the first time. The displacement of the Sun shadow measured in 2021 correlates well with the transverse IMF component measured in situ by spacecraft near the Earth, with a time lag of 3:31 $\pm$ 0:12 days. The displacement of the Sun shadow was also simulated using Parker's classic IMF model, yielding a time lag of 2:06 $\pm$ 0:04 days. This deviation may provide valuable insights into the magnetic field structure, which can improve space weather research.
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https://arxiv.org/abs/2410.09064
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2426b284577f609b5f2e3cb6c964a8d6e903c21c220bdfd83af21d9b633d6995
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2026-01-07T00:00:00-05:00
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Spatio-temporal analysis of extreme winter temperatures in Ireland
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arXiv:2412.10796v2 Announce Type: replace Abstract: We analyse extreme daily minimum temperatures in winter months over the island of Ireland from 1950-2022. We model the marginal distributions of extreme winter minima using a generalised Pareto distribution (GPD), capturing temporal and spatial non-stationarities in the parameters of the GPD. We investigate two independent temporal non-stationarities in extreme winter minima. We model the long-term trend in magnitude of extreme winter minima as well as short-term, large fluctuations in magnitude caused by anomalous behaviour of the jet stream. We measure magnitudes of spatial events with a carefully chosen risk function and fit an r-Pareto process to extreme events exceeding a high-risk threshold. Our analysis is based on synoptic data observations courtesy of Met \'Eireann and the Met Office. We show that the frequency of extreme cold winter events is decreasing over the study period. The magnitude of extreme winter events is also decreasing, indicating that winters are warming, and apparently warming at a faster rate than extreme summer temperatures. We also show that extremely cold winter temperatures are warming at a faster rate than non-extreme winter temperatures. We find that a climate model output previously shown to be informative as a covariate for modelling extremely warm summer temperatures is less effective as a covariate for extremely cold winter temperatures. However, we show that the climate model is useful for informing a non-extreme temperature model.
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https://arxiv.org/abs/2412.10796
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853be7afce33e48a2296486a9f685810c6c098f20e40b4304da8f1a6878c78f7
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2026-01-07T00:00:00-05:00
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Theoretical analysis of performance limitation of computational refocusing in optical coherence tomography
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arXiv:2501.13874v3 Announce Type: replace Abstract: High-numerical-aperture optical coherence tomography (OCT) enables sub-cellular imaging but faces a trade-off between lateral resolution and depth of focus. Computational refocusing can correct defocus in Fourier-domain OCT, yet its limitations remain unaddressed theoretically. We formulate the lateral imaging process of OCT by using pupil-based imaging theory and the constraints of the computational refocusing in point-scanning OCT and spatially-coherent full-field OCT (FFOCT) are analyzed. The constrains in lateral sampling density and the confocality are considered, and it is shown that the maximum correctable defocus (MCD) is primarily limited by confocality in point-scanning OCT, while spatially-coherent FFOCT has no such constraint and can achieve virtually infinite MCD with a proper and reasonable sampling density. This makes spatially-coherent FFOCT particularly suitable for optical coherence microscopy.
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https://arxiv.org/abs/2501.13874
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c46f2600b3a3b55d6f8349ab10049a18fe742f3e087f68e779a3fed794fe0837
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2026-01-07T00:00:00-05:00
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Optically trapped exciton-polariton condensates in a perovskite microcavity
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arXiv:2501.16861v2 Announce Type: replace Abstract: We demonstrate room temperature optical trapping and generation of high-order angular harmonics in exciton-polariton condensates in a monocrystalline CsPbBr$_3$ perovskite-filled microcavity. Using an annular nonresonant excitation profile focused onto the perovskite, we observed power-driven switching between different transverse modes of the optically induced trap. We explore the interplay between the perovskite crystal dimensions and the optical trap diameter that allows the condensate to transition from whispering gallery-like petal shapes to extended ripple states. Our results underline the feasibility in creating high-order quantum states in perovskite polariton condensates for reconfigurable and structured room temperature nonlinear lasing.
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https://arxiv.org/abs/2501.16861
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cd10b3f16ae76868fd98ae29bd20a5d4a8068ef8846466b313bc4e2a1b7c3741
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2026-01-07T00:00:00-05:00
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A practical guide to estimation and uncertainty quantification of aerodynamic flows
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arXiv:2502.20280v3 Announce Type: replace Abstract: Many applications in aerodynamics, particularly in closed-loop control, depend on sensors to estimate the evolving state of the flow. This estimation task is inherently accompanied by uncertainty due to the noisy measurements of sensors or the non-uniqueness of the underlying mapping. Knowledge of this uncertainty can be as important for decision-making as that of the state itself. Uncertainty tracking is challenged by the often-nonlinear relationship between the measurements and the flow state. For example, a collection of passing vortices leaves a footprint in wall pressure that depends nonlinearly on the vortices' strengths and positions. In this paper, we outline recent approaches to flow estimation and illuminate them with worked examples and selected case studies. We review relevant probability tools, including sampling and estimation, in the powerful setting of Bayesian inference and demonstrate these in static flow estimation examples. We then review unsteady examples and illustrate the application of sequential estimation, and particularly, the ensemble Kalman filter. Finally, we discuss uncertainty quantification in neural network approximations of the mappings between sensor measurements and flow states. Recent aerodynamic applications have shown that the flow state can be encoded into a very low-dimensional latent space. We discuss the uncertainty implications of this encoding.
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https://arxiv.org/abs/2502.20280
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51055c6c00ecc3f6c3938d63a8689aaab7d3d3949fe735f7ec467d2f78ec9286
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2026-01-07T00:00:00-05:00
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Light-Driven Skyrmion Crystal Generation in Plasmonic Metasurfaces Through the Inverse Faraday Effect
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arXiv:2503.23800v2 Announce Type: replace Abstract: Skyrmions are topological structures defined by a winding vector configuration that yields a quantized topological charge. In magnetic materials, skyrmions manifest as stable, mobile spin textures, positioning them at the forefront of spintronics research. Meanwhile, their optical counterparts unlock new possibilities for manipulating and directing light at the nanoscale. Exploring the territories where magnetism and optics meet therefore holds immense promise for ultrafast control over magnetic processes. Here, we report the generation of a skyrmion-topological lattice through the inverse Faraday effect in a plasmonic metasurface. Specifically, a hexagonal array of gold nanodisks induces unidirectional drift photocurrents in each nanodisk, while counterpropagating phantom currents arise in the hexagonal interstices. This interplay creates a lattice of skyrmionic magnetic textures. Crucially, the all optical, large scale formation of skyrmions potentially at ultrafast timescales offers a pathway for integrating these topological spin textures into magnetic materials, laying the groundwork for next-generation data storage and processing technologies.
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https://arxiv.org/abs/2503.23800
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1c0779b5dfc253c21eada872cf6b3bd1a9d41c5d4a04c56b1970547734838044
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2026-01-07T00:00:00-05:00
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Electrically tunable nonrigid moire exciton polariton supersolids at room temperature
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arXiv:2504.11057v2 Announce Type: replace Abstract: A supersolid is a macroscopic quantum state which sustains superfluid and crystallizing structure together after breaking the U(1) symmetry and translational symmetry. On the other hand, a moire pattern can form by superimposing two periodic structures along a particular direction. Up to now, supersolids and moire states are disconnected from each other. In this work we show that exciton polariton supersolids can form moire states in a double degenerate parametric scattering process which creates two constituted supersolids with different periods in a liquid crystal microcavity. In addition, we demonstrate the nonrigidity of the moire exciton polariton supersolids by electrically tuning the wavevector and period of one supersolid component with another one being fixed. Our work finds a simple way to link moire states and supersolids, which offers to study nontrivial physics emerging from the combination of moire lattices and supersolids which can be electrically tuned at room temperature.
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https://arxiv.org/abs/2504.11057
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18441a393a5bf334febf3cac5bc4312300a0c45ebef8768a5b37acbfa510b8c5
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2026-01-07T00:00:00-05:00
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Optically Switchable Fluorescence Enhancement at Critical Interparticle Distances
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arXiv:2504.11541v5 Announce Type: replace Abstract: Plasmonic nanostructures provide electric field localization to be used as a fluorescence enhancement tool for the closely located fluorophores. However, metallic structures exhibit non-radiative energy transfer at close proximity, which suppresses the boost in the photoluminescence spectrum due to inhomogeneous medium. Compensation to non-radiative losses is fundamentally restricted, therefore defining the critical interparticle distances, where the fluorescence enhancement is detectable hold utmost importance for device applications. In this work, we numerically identified the critical interparticle distances of a metal nanoparticle (MNP) and quantum emitters (QEs) with angstrom resolution by analyzing the interplay between quantum yield and non-radiative decay. By engaging a collimated light application on silver nanoparticle (AgNP) placed at a critical distance, we simulated an active fluorescence enhancement switch yielding observable 7-fold increase in fluorescence intensity. The provided free space simulation includes the complete response of AgNP with retardation and higher order multi-polar effects for which the previous analytical works fall short. While the model bridges the absorption and emission spectra via corresponding Stokes shift values and presents a general approach for the interaction of QEs and MNPs in Rayleigh regime, it can be extended to Mie regime for larger QEs and can be modified for dielectric device environment.
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https://arxiv.org/abs/2504.11541
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a3e59b24212bfd116ad60fc46d65fa85dc42467091d4adec935feda4322cae52
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2026-01-07T00:00:00-05:00
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Dynamics of a compressible gas injected into a confined porous layer
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arXiv:2505.05412v3 Announce Type: replace Abstract: Underground gas storage is a critical technology in global efforts to mitigate climate change. In particular, hydrogen storage offers a promising solution for integrating renewable energy into the power grid. When injected into the subsurface, hydrogen's low viscosity compared to the resident brine causes a bubble of hydrogen trapped beneath caprock to spread rapidly into an aquifer through release of a thin gas layer above the brine, complicating recovery. In long aquifers, the large viscous pressure drop between source and outlet induces significant pressure variations, potentially leading to substantial density changes in the injected gas. To examine the role of gas compressibility in the spreading dynamics, we use long-wave theory to derive coupled nonlinear evolution equations for the gas pressure and gas/liquid interface height, focusing on the limit of long domains, weak gas compressibility and low gas/liquid viscosity ratio. Simulations are supplemented with a comprehensive asymptotic analysis of parameter regimes. Unlike the near-incompressible limit, in which gas spreading rates are dictated by the source strength and viscosity ratio, and compressive effects are transient, we show how compression of the main gas bubble can generate dynamic pressure changes that are coupled to those in the thin gas layer that spreads over the liquid, with compressive effects having a sustained influence along the layer. This coupling allows compressibility to reduce spreading rates and gas pressures. We characterise this behaviour via a set of low-order models that reveal dominant scalings, highlighting the role of compressibility in mediating the evolution of the gas layer.
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https://arxiv.org/abs/2505.05412
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4c58ec8904afeec9722c28a883cff2f25ee19ddc73f5e20fe6d5c6aa30cf9a2c
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2026-01-07T00:00:00-05:00
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Optical excitation and stabilization of ultracold field-linked tetratomic molecules
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arXiv:2506.17341v2 Announce Type: replace Abstract: We propose a coherent optical population transfer of weakly bound field-linked (FL) tetratomic molecules (tetramers) to deeper FL bound states using stimulated Raman adiabatic passage. We consider static-electric-field shielded polar alkali-metal diatomic molecules and corresponding FL tetramers in their $\textrm{X}^1\Sigma^+$+$\textrm{X}^1\Sigma^+$ ground electronic state. We show that the excited metastable $\textrm{X}^1\Sigma^+$+$\textrm{b}^3\Pi$ electronic manifold supports FL tetramers in a broader range of electric fields with collisional shielding extended to zero field. We calculate the Franck-Condon factors between the ground and excited FL tetramers and show that they are highly tunable with the electric field. We also predict photoassociation of ground-state shielded molecules to the excited FL states in free-bound optical transitions. We propose proof-of-principle experiments to implement stimulated Raman adiabatic passage and photoassociation using FL tetramers, paving the way for the formation of deeply bound ultracold polyatomic molecules.
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https://arxiv.org/abs/2506.17341
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3700067539271b8af8c655d5be9f4e4befaeb464bdb197f3af106a3a2e8d02f1
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2026-01-07T00:00:00-05:00
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On the Role of Color Temperature and Color Rendering Index of White-Light LEDs on the Theoretical Efficiency Limit of Indoor Photovoltaics
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arXiv:2506.20811v2 Announce Type: replace Abstract: As the Internet of Things (IoT) continues to grow, the demand for sustainable indoor power sources is increasing. Indoor photovoltaics (IPVs), which are currently in development, present a renewable solution but need to be designed to match specific light sources. While previous studies have emphasized the role of white-light LED correlated color temperature (CCT) in determining IPV efficiency and optimum bandgap energy, the role of color rendering index (CRI) remains less understood. In this study, we employ detailed-balance calculations to assess the theoretical maximum efficiency and optimal bandgap energies of IPVs under commercial white-light LED irradiance varying in both CCT (2200 K to 6500 K) and CRI (70, 80, and 90). Our results confirm that lower CCTs indeed yield higher efficiencies and lower optimal bandgaps. However, contrary to prior assumptions that CRI has negligible impact on IPV material choice and performance, we demonstrate that high-CRI LEDs necessitate the use of materials with significantly lower bandgap energies for optimum efficiency due to the shift towards red in the higher CRI irradiance spectra. We also evaluate the performance of various IPVs at fixed bandgaps, revealing that while optimal IPV performance is achieved with wide-bandgap materials under lower CRI lighting, mature technologies like silicon and CdTe benefit from high-CRI illumination. These findings underscore the need to consider both CCT and CRI in the design, evaluation, and choice of IPVs for indoor IoT applications.
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https://arxiv.org/abs/2506.20811
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fe6c5831232fca5d3ef8ec707c00a55f50fc819cfc8a525738cef5ff0561e332
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2026-01-07T00:00:00-05:00
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All-Dielectric Metasurface with a Two-Dimensional Locally Flat Photonic Band
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arXiv:2506.20871v2 Announce Type: replace Abstract: Photonic flatbands offer promising light-matter interaction due to their unique slow-light nature. In recent years, flatbands have also attracted significant interest in optical engineering because of their angle-insensitive resonant characteristics. However, to date, no studies have reported the dispersionless behavior of flatbands under arbitrary two-dimensional incident angles. Here, we present a two-dimensional photonic flatband created using a silicon metasurface with a Lieb lattice-inspired structure which demonstrates a locally flat photonic band for both transverse electric (TE) and transverse magnetic (TM) polarized light. Employing Fourier imaging, we analyze the energy-momentum dispersion of the flatband metasurface under arbitrary two-dimensional incident angles, demonstrating dispersionless flatbands with a change in resonance within $\pm2 nm$ up to $\pm24\^o$ or $\pm5\^o$, depending on the polarization state and incident angle. This geometry can be adapted for various applications in local field enhancement, enhanced photodetection, and augmented reality displays.
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https://arxiv.org/abs/2506.20871
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6476200b25c5b9beee4e0c3c41c40bcabcda17c6c864121d2001080eba060205
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2026-01-07T00:00:00-05:00
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Magic wavelength at 477 nm for the strontium clock transition
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arXiv:2507.04532v2 Announce Type: replace Abstract: We report the experimental measurement of a magic wavelength at 476.82362(8) nm for the 88Sr clock transition. The magic wavelength is determined through AC-Stark shift spectroscopy of atoms in an optical dipole trap. The value slightly deviates from the theoretical prediction by 0.061(54) nm. This magic wavelength, being shorter than the common one at 813 nm, will be important for applications such as Bragg pulses for matter-wave interferometry involving both clock states. This work also paves the way for quantum simulation with a shorter lattice.
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https://arxiv.org/abs/2507.04532
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c64ebec7eb290e1e4e430b50c5c40377b75d23453b07fbef1f3b245d379ee739
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2026-01-07T00:00:00-05:00
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Scaling transition in horizontal convection near the density maximum
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arXiv:2508.12289v3 Announce Type: replace Abstract: Horizontal convection (HC) serves as a canonical model for geophysical and industrial flows driven by differential heating along a surface. While the classical Oberbeck-Boussinesq (OB) approximation is well-established, the impact of a nonlinear equation of state, specifically the density maximum of water near $4^\circ\mathrm{C}$, remains underexplored. This study investigates Non-Oberbeck-Boussinesq (NOB) effects on HC via direct numerical simulations (DNS) over a Rayleigh number range of $10^6 \le Ra \le 5\times 10^{10}$. We examine two configurations: Classical HC (CHC) and Symmetric HC (SHC). Our results reveal that the NOB-SHC case undergoes a structural transition, evolving from a bicellular structure to a full-depth, single-roll circulation driven by central `mixing plumes'. This reorganization manifests as transitional anomalies in Reynolds number ($Re$) scaling, whereas the emergence of full-depth plumes fundamentally alters the heat transport mechanism. Consequently, unlike the classical Rossby scaling ($Nu \sim Ra^{1/5}$) observed in reference cases, the NOB-SHC regime exhibits an enhanced heat transport scaling ranging from $Nu \sim Ra^{1/4}$ to $Ra^{1/3}$. To rationalize this behavior, we extend the Shishkina-Grossmann-Lohse (SGL) theory by incorporating a generalized potential energy transfer term ($\Phi_{i2}$). The theoretical framework demonstrates that the global scaling law is dictated by the characteristic plume height ($\hat{z}$). Specifically, when plumes penetrate the entire cavity depth ($\hat{z} \sim H$), as observed in the NOB-SHC case, the flow transcends classical bounds for OB HC, accessing a regime analogous to Rayleigh B\'enard convection. The proposed theory successfully unifies the scaling laws for both OB and NOB fluids, showing excellent agreement with numerical data.
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https://arxiv.org/abs/2508.12289
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1aecf4033363d3853924a07c3d9a9093f55f76f2e7a8ed711a67e57dd863ba3a
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2026-01-07T00:00:00-05:00
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Optimizing steady-state synchronization in disordered semiconductor lasers
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arXiv:2509.07302v2 Announce Type: replace Abstract: Disorder can profoundly influence synchronization in networks of nonlinear oscillators, sometimes enhancing coherence through external tuning. In semiconductor lasers, however, achieving high-quality steady-state synchronization is desired, while intrinsic and typically uncontrollable disorder poses a major challenge. Under fixed frequency disorder, we investigate homogeneous fully coupled external-cavity semiconductor lasers governed by the complex, time-delayed Lang-Kobayashi equations with experimentally relevant parameters and identify an optimal coupling strength that maximizes steady-state synchronization in the weak-coupling regime. This optimum appears for any fixed configuration of intrinsic frequency detuning and scales inversely with the number of lasers, leading to a linear scaling of the total coupling cost with the number of lasers. A theory based on an effective thermodynamic potential explains this disorder-mediated optimization, revealing a general mechanism by which moderate coupling can overcome static heterogeneity in nonlinear physical systems.
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https://arxiv.org/abs/2509.07302
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eaf298e698252625d0fb78c8973be7bf3e8f9a684cf8517eb81ee9765f2d0a2d
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2026-01-07T00:00:00-05:00
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High-Fidelity Simulations of Two Miscible Fluids in Small Scale Turbulent Mixers Using a Variational Multiscale Finite Element Method
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arXiv:2509.12029v2 Announce Type: replace Abstract: Turbulent mixers have been widely used in industrial settings for chemical production and increasingly for therapeutic nanoparticle formulation by antisolvent precipitation. The quality of the product is closely related to the fluid and mixing dynamics inside the mixers. Due to the rapid time scales and small sizes of many turbulent mixing geometries, computational fluid dynamics simulations have been the primary tool used to predict and understand fluid behavior within these mixers. In this study, we used the residual-based variational multiscale finite element method to perform high-fidelity turbulent simulations on two commonly used turbulent mixers: the multi-inlet vortex mixer (MIVM) and the confined impinging jets mixer (CIJM). We simulated two geometric variations, two-inlets and four-inlets, of the MIVM and two different inflow ratios of the CIJM. Through detailed turbulence results, we identify differences in turbulence onset, total energy, and mixing performance of the two MIVM configurations. With the CIJM results, we demonstrate the effect of the flow rate ratio on the impingement behavior, and as a result, on the mixing performance and turbulence. The cross-comparison between the two mixers shows key differences in turbulence and mixing behaviors, such as the turbulence onset, the energy decay, and the output mixing index. This study demonstrates the importance of a high-accuracy numerical scheme in simulating the turbulent mixers and understanding the similarities and differences among mixers. Furthermore, the results show potential for optimizing the operating conditions to achieve the best mixing performance.
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https://arxiv.org/abs/2509.12029
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cc2aa9c2d637dabb0d1ee4b7f45418047dceb436a1d6bd18892e7a7e8cbcb646
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2026-01-07T00:00:00-05:00
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The Role of Phase and Spatial Modes in Wave-Induced Plasma Transport
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arXiv:2509.15729v2 Announce Type: replace Abstract: We derive a two-dimensional symplectic map for particle motion at the plasma edge by modeling the electrostatic potential as a superposition of integer spatial harmonics with relative phase shift, then reduce it to a two-wave model to study the transport dependence on the perturbation amplitudes, relative phase, and spatial-mode choice. Using particle transmissivity as a confinement criterion, identical-mode pairs exhibit phase-controlled behavior: anti-phase waves produce destructive interference and strong confinement while in-phase waves add constructively and drive chaotic transport. Mode-mismatched pairs produce richer phase-space structure with higher-order resonances and sticky regions; the transmissivity boundaries become geometrically complex. Box-counting dimensions quantify this: integer dimension smooth boundaries for identical modes versus non-integer fractal-like dimension for distinct modes, demonstrating that phase and spectral content of waves jointly determine whether interference suppresses or promotes transport.
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https://arxiv.org/abs/2509.15729
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da1e8a008564b2e2476c96ba7f05caf0c8050cbd87fc90f7d81b3cf0fa543506
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2026-01-07T00:00:00-05:00
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Diagnostics of a Multicusp-Assisted Inductively-Coupled Radio-Frequency Plasma Source for Plasma Immersion Ion Implantation
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arXiv:2510.18384v2 Announce Type: replace Abstract: In this article, we present a detailed characterisation of a multicusp-assisted inductively coupled RF plasma source for plasma immersion ion implantation (PIII). Using laser-induced fluorescence (LIF) and RF-compensated Langmuir probe diagnostics, we measured ion temperature T i and drift velocity v z in argon plasmas near an immersed electrode. The multicusp configuration enhances plasma density at low pressure, enabling stable operation down to 0.8 mTorr. Timeaveraged measurements show no detectable perturbation near the pulsed electrode, indicating full plasma recovery between high-voltage pulses. LIF-derived potential profiles match Riemann's presheath theory, and ion velocity distributions reveal acceleration consistent with sheath dynamics. These results support the use of LIF for steady-state characterisation of the bulk and presheath regions in PIII systems.
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https://arxiv.org/abs/2510.18384
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2795fd06fb66d9e788576e37f7aadcb3625bc474ca37a56403cda5651e3863ef
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2026-01-07T00:00:00-05:00
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Effects of thermal annealing and film thickness on the structural and optical properties of indium-tin-oxide thin films
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arXiv:2512.01441v3 Announce Type: replace Abstract: Indium-tin oxide (ITO) is a crucial functional layer for the optoelectronic applications, such as non-volatile color display thin films based on the ITO/phase-change material (PCM)/ITO/reflective metal multilayer structures on a silicon substrate. In addition to non-volatile color tuning by PCMs, thermally induced crystallization may alter the optical properties of ITO layers as well. But the potential change in color of the ITO layers is not considered so far. In this work, we investigate the structural and optical properties of ITO thin films via X-ray diffraction, spectroscopic ellipsometry and ultraviolet-visible spectrophotometry measurements. After thermal annealing at 250 {\deg}C, the ITO thin films of 15-100 nm get crystallized with strong changes in refractive index n and extinction coefficient k in the visible light range. However, for the 5-nm ITO thin film, crystallization is only observed after thermal annealing at 350 {\deg}C and the change in color is limited upon phase transition. We provide a colormap of the ITO/platinum/silicon structure in terms of the annealing temperature (150-350 {\deg}C) and ITO film thickness (5-100 nm). Our work suggests that the intrinsic change in colors of ITO layers should also be considered for the PCM-based reconfigurable display application.
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https://arxiv.org/abs/2512.01441
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994ea58744b45f285c698a07f19067ea1e4dd95d4ff3f20d6d5c460668773a53
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2026-01-07T00:00:00-05:00
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A Dynamical-Time Framework for the Dynamics of Charged Particles
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arXiv:2512.19768v2 Announce Type: replace Abstract: We present a dynamical framework for modeling the motion of point-like charged particles, with or without mass, in general external electromagnetic fields. A key feature of this formulation is the treatment of time coordinate as a dynamical variable. The framework applies to the relativistic regime while consistently admitting a nonrelativistic limit. We also introduce a representation of particle trajectories in velocity space, which provides clear insight into the nature and asymptotic behavior of the dynamics. As an application, we compare the motion of massive and massless particles in a constant electromagnetic field and find that, for identical field configurations, their asymptotic behavior is independent of both mass and initial conditions. Finally, we explore the computational advantages of the dynamical-time formulation over the conventional uniform-time approach in two case studies: a uniform electromagnetic field, and an elliptically polarized wave propagating along a uniform magnetic field. In both scenarios, the proposed scheme exhibits improvements in accuracy and computational efficiency.
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https://arxiv.org/abs/2512.19768
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499c4e36f5b053caa7fa981855a93fdadcb4d641226f7c81cd1c26df1b26b239
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2026-01-07T00:00:00-05:00
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The Physics of Causation
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arXiv:2601.00515v2 Announce Type: replace Abstract: Assembly theory (AT) introduces a concept of causation as a material property, constitutive of a metrology of evolution and selection. The physical scale for causation is quantified with the assembly index, defined as the minimum number of steps necessary for a distinguishable object to exist, where steps are assembled recursively. Observing countable copies of high assembly index objects indicates that a mechanism to produce them is persistent, such that the object's environment builds a memory that traps causation within a contingent chain. Copy number and assembly index underlie the standardized metrology for detecting causation (assembly index), and evidence of contingency (copy number). Together, these allow the precise definition of a selective threshold in assembly space, understood as the set of all causal possibilities. This threshold demarcates life (and its derivative agential, intelligent and technological forms) as structures with persistent copies beyond the threshold. In introducing a fundamental concept of material causation to explain and measure life, AT represents a departure from prior theories of causation, such as interventional ones, which have so far proven incompatible with fundamental physics. We discuss how AT's concept of causation provides the foundation for a theory of physics where novelty, contingency and the potential for open-endedness are fundamental, and determinism is emergent along assembled lineages.
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https://arxiv.org/abs/2601.00515
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Academic Papers
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a289f31177e9a4312a40c36eec0148a678eb6df84e9abd5761de006f3d914ad2
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2026-01-07T00:00:00-05:00
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Overcoming the space-charge dilemma in low-energy heavy ion beams via a multistage acceleration lens system
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arXiv:2601.01367v2 Announce Type: replace Abstract: Low-energy heavy-ion beams are fundamentally limited by severe space-charge divergence, which constrains the transportable beam current to a few microamperes in conventional electrostatic accelerators. This limitation is particularly critical for high-mass ions, where the generalized perveance increases rapidly because of their low velocity. Here, we demonstrate that this apparent space-charge limit can be overcome by shaping the electrostatic potential configuration of an existing multistage accelerator, thereby transforming the acceleration column itself into a combined acceleration-focusing column. By optimizing the interstage voltage configuration, a strong electrostatic lens effect is superimposed on the accelerating field to counteract space-charge-driven expansion. We formulate a generalized design framework that quantitatively maps the transport 'design window' in terms of beam current, ion mass, and acceleration voltage. For gold ions at 64 keV, this approach enables stable transport of beam currents exceeding 100 microA, more than an order of magnitude higher than the conventional limit. Numerical phase-space analysis shows that this improvement is achieved by prioritizing envelope control over emittance preservation, a trade-off intrinsic to space-charge-dominated regimes. Our results establish a universal and practical guideline for high-current heavy-ion beam transport, relevant to fusion plasma diagnostics, ion implantation, and massive molecular ion applications.
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https://arxiv.org/abs/2601.01367
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Academic Papers
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fda48f4473220199daa8409060c6c84eef5caf2447035971b1e7da85c5a870b6
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2026-01-07T00:00:00-05:00
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Warming-driven rise in soil moisture entropy signals destabilization of the Asian Water Tower
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arXiv:2601.01534v2 Announce Type: replace Abstract: The Tibetan Plateau (TP), known as the "Asian Water Tower," is currently undergoing a rapid wetting trend. While this moisture increase is often viewed as beneficial for water availability, it remains unclear whether the hydrological system itself is becoming more resilient or drifting toward instability. Here, we apply an entropy-based framework to quantify the changing structural organization of the TP's soil moisture system. We show that from 2000 to 2024, regional wetting has driven a long-term decline in entropy, reflecting an increase in system order and stability due to enhanced hydrological buffering capacity. This stability is modulated by the El Ni\~no-Southern Oscillation (ENSO), which regulates regional heterogeneity via a distinct spatial dipole. Crucially, however, CMIP6 climate projections reveal an alarming reversal: future warming triggers a rise in entropy. This transition signals a loss of systemic resilience, characterized by intensified spatial disorder and potential abrupt regime shifts by the mid-century. Our findings suggest that while current wetting provides a stabilizing buffer, continued warming is projected to amplify spatial heterogeneity, thereby destabilizing the Asian Water Tower, with significant risks for downstream water security.
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https://arxiv.org/abs/2601.01534
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5f157902dca3f1a6d96b576b69da03defd21da9a0504625ca5fe421ac949fb9b
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2026-01-07T00:00:00-05:00
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Simourg2.0 - Geant4 application for simulation of nuclear detectors with simple geometries
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arXiv:2601.01640v2 Announce Type: replace Abstract: Simourg is a software based on the Geant4 toolkit and provides the Monte Carlo simulation of nuclear spectrometric setups with simple geometries for such applications as nuclear decay research, radiation safety, and nuclear medicine. With just a few command lines, users can define simple geometries, materials, and radiation sources to obtain reliable approximations for typical experimental setups. Simourg version 2.0, currently in its prerelease stage, introduces extended functionality for data extraction, geometry configuration, debugging, and visualization.
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https://arxiv.org/abs/2601.01640
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Academic Papers
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75dcbb078f1758358aa2ed756d631ba1c1ede2add72ee983ac527f1f13661704
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2026-01-07T00:00:00-05:00
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Magnetically Induced Transparency-Absorption and Normal-Anomalous Dispersion Characteristics of ${}^{87}\text{Rb}$ Medium or Any J-Type Configuration Atomic Vapors Subject to a Vector Magnetic Field and a Weak Resonant Pump
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arXiv:2601.02113v2 Announce Type: replace Abstract: We have developed an analytical framework for magnetically induced transparency-absorption (MITA) and normal-anomalous dispersion (MINAD) in a weakly driven ${}^{87}\text{Rb}$ vapor, or any J-type three-level system, under a vector magnetic field. By solving the Bloch equations in the stationary, quasi-stationary, and short-pulse regimes, we obtained closed-form expressions for the atomic populations and coherences and identified a bifurcation in the oscillatory dynamics at zero longitudinal Zeeman splitting. The Fourier-domain analysis reveals alternating transparency/absorption and normal/anomalous dispersion with frequency-dependent sign reversals, enabling spectrally selective filtering and group-delay effects. Slow oscillatory behavior in the radio-frequency range makes the system suitable for weak magnetic-field sensing, while fast oscillations at optical frequencies suggest applications in spectral filtering and frequency-comb-like signal shaping. The results provide a theoretical basis for experimental observation of MITA/MINAD and for optimizing atomic-vapor platforms for precision magnetometry and related photonic functionalities.
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https://arxiv.org/abs/2601.02113
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b0e1013d99db98ac42666adf2abc9904d8a90f5e51a76428031a581bca997049
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2026-01-07T00:00:00-05:00
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Addressing intramolecular vibrational redistribution in a single molecule through pump and probe surface-enhanced vibrational spectroscopy
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arXiv:2601.02117v2 Announce Type: replace Abstract: The development of accurate tools to characterize Intramolecular Vibrational Redistribution (IVR) is of major interest in chemistry. In this context, surface-enhanced vibrational spectroscopies stand up as well-established techniques to study molecular vibrational lines and populations with a sensitivity that can reach the singe-molecule level. However, to date, this possibility has not been fully developed to address IVR. Here, we establish a quantum mechanical framework based on molecular optomechanics that accounts for IVR, and adopt it to analyze strategies to optimize IVR characterization by vibrational spectroscopy. In particular, we model two different pump-and-probe configurations where the vibrational pumping is provided either by infrared laser illumination or by Stokes SERS. We show for the two pumping configurations the existence of clear signatures on the anti-Stokes SERS spectra of population transfer between coupled vibrational modes in a molecule. Our calculations adopt realistic molecular and SERS parameters, suggesting that these signatures of IVR are accessible at the single-molecule level with current experimental platforms.
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https://arxiv.org/abs/2601.02117
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b82bb21a3e812c02b7fe584f6ca32ff30bd0acfcca8625e26b1ff49a6b70c2a2
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2026-01-07T00:00:00-05:00
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A hitchhiker's guide to nuclear polarization in muonic atoms
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arXiv:2501.15274v3 Announce Type: replace-cross Abstract: I consider the so-called nuclear polarization correction to the 1S-levels in light to intermediate muonic atoms. An easy to use recipe to compute it is given. The calculation includes the effect of the nucleon polarization, i.e. the contribution from inelastic states in the hadronic range, and Coulomb corrections beyond the leading logarithm approximation to both nuclear and nucleon polarization. I provide numerical estimates for $4\leq Z\leq41$, compare to the estimates in the literature and discuss the need for future improvements.
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https://arxiv.org/abs/2501.15274
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139daac56aeac32c15e0641a75634665b5de170a150f1df4fa0f4e5ab05d96a4
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2026-01-07T00:00:00-05:00
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Thermodynamic uncertainty relations for multi-terminal systems with broken time-reversal symmetry
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arXiv:2503.13851v3 Announce Type: replace-cross Abstract: We investigate the thermodynamic uncertainty relations (TURs) in steady-state transport for a multi-terminal system consisting of two conducting terminals and N-2 probe terminals, within the linear response regime under broken time-reversal symmetry. We independently derive exact bounds on the TURs for the steady-state particle and heat currents under a strong constraint on the Onsager coefficients. Based on our proposed exact bounds, the analysis reveals that the bounds differ for particle and heat currents and are dependent on the system parameters. Furthermore, we demonstrate that under specific parameter conditions, the TURs of the particle and heat currents have a unified minimum value that depends solely on the number of terminals.
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https://arxiv.org/abs/2503.13851
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9a18f640d29b2c74fb4cbd3c8a0c8b3cd7efa03118fbe5bf45fa7e6d26fbb8ad
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2026-01-07T00:00:00-05:00
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Transforming Acidic Corrosion and Embrittlement into a Hydrogen-Trapping Cage
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arXiv:2506.05481v5 Announce Type: replace-cross Abstract: The vision of a hydrogen economy demands efficient platforms to close the gap between sustainable proton sources and solid-state hydrogen carriers. Metal hydrides serve as key carriers, yet their synthesis remains constrained by the energy-intensive use of high-pressure H2, which fragments the hydrogen chain. Here, we overturn this paradigm by transforming two classic degradation mechanisms, acidic corrosion and hydrogen embrittlement, into a constructive materials-design strategy. We demonstrate that synergistic control of these processes in acid enables the in-situ engineering of a "hydrogen-trapping cage" (HTC) microstructure within metals. Composed of a dense defect network, this cage directly captures and stabilizes protons as hydrides under mild conditions, guided by the universal criterion |DeltaPeq| > DeltaPph. Using this platform, we synthesize over 20 hydrides, including challenging targets such as LiH and NaH, and showcase its functional power with a cage-rich titanium hydride electrocatalyst. This catalyst achieves an exceptional current density of 1.07 A cm-2 for nitrate-to-ammonia conversion, attributed to rapid H- transport within the engineered cage. This work establishes a transformative "failure-to-function" paradigm, delivering an integrated platform that unifies hydrogen capture, stabilization, and conversion.
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https://arxiv.org/abs/2506.05481
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ff475eef99f7532f9cc25e9b3288ce8f84ea53d81ad047d9d39d04da3e56333c
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2026-01-07T00:00:00-05:00
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Making the $\mu$OST of the Muon Collider
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arXiv:2506.19301v2 Announce Type: replace-cross Abstract: The Muon Collider, recently highlighted as Recommendation 1 in the U.S. National Academies report on Elementary Particle Physics, offers a unique opportunity for fixed-target experiments with high energy and luminosity. This paper outlines some of the challenges and possibilities for fixed-target experiments to study the multi-dimensional structure of hadrons at the Muon Collider. We present a sketch of an experiment making use of the high-energy muon beam from the Muon Collider that could serve as the next-generation hadronic physics experiment after the Electron-Ion Collider.
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https://arxiv.org/abs/2506.19301
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b0b84135155196e3c137882820cead7a9db8f6137bd9ed0b853003272110cb87
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2026-01-07T00:00:00-05:00
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From Ising to Potts: Physics-inspired Potts machines of coupled oscillators for low-energy sampling and combinatorial optimization
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arXiv:2507.18379v2 Announce Type: replace-cross Abstract: The $q$-state Potts model is a fundamental model in statistical physics that generalizes the Ising model and plays a key role in the study of phase transitions, critical phenomena, complex systems, and combinatorial optimization. Sampling low-energy configurations of the $q$-state Potts model is essential to these studies, but it remains challenging. While physics-inspired dynamical sampling has been extensively explored for the Ising case ($q=2$) in the form of Ising machines, its generalization to general $q$-state Potts models remains largely unexplored. To fill this gap, we propose a class of physics-inspired dynamical samplers that directly target general $q$-state Potts models, which we refer to as the oscillator Potts machine (OPM). We show, through theoretical analysis and numerical experiments, that the OPM exhibits a systematic low-energy bias with respect to the underlying Potts energy landscape. Furthermore, we demonstrate, via phase perturbation analysis, that the OPM, as overdamped Langevin dynamics, can be realized with a network of self-sustaining oscillators, demonstrating that the OPM is naturally realizable in hardware using standard technology such as CMOS. We design a small-scale ring-oscillator circuit that implements a three-state OPM and validate its operation through transistor-level simulation. Leveraging the low-energy bias of the OPM for Potts models, we then apply it to large-scale max-$K$-cut problems by mapping these instances to $q$-state Potts Hamiltonians and compare its performance against established algorithms. Our results position the OPM as a promising, physically grounded dynamical system framework for multi-state sampling and combinatorial optimization.
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https://arxiv.org/abs/2507.18379
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544aacfe0f7e6371bec7294133d55a0223647f3d2b2a10b2c22cb8849137b625
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2026-01-07T00:00:00-05:00
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plasmonX: an Open-Source Code for Nanoplasmonics
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arXiv:2510.12731v2 Announce Type: replace-cross Abstract: We present the first public release of plasmonX, a novel open-source code for simulating the plasmonic response of complex nanostructures. The code supports both fully atomistic and implicit descriptions of nanomaterials. In particular, it employs the frequency-dependent fluctuating charges ($\omega$FQ) and dipoles ($\omega$FQF$\mu$) models to describe the response properties of atomistic structures, including simple and $d$-metals, graphene-based structures, and multi-metal nanostructures. For implicit representations, the Boundary Element Method is implemented in both the dielectric polarizable continuum model (DPCM) and integral equation formalism (IEF-PCM) variants. The distribution also includes a post-processing module that enables analysis of electric field-induced properties such as charge density and electric field patterns.
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https://arxiv.org/abs/2510.12731
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391fd7d17b727727dbf14561975b8521891178720ecf3617140e24be675feb9f
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2026-01-07T00:00:00-05:00
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Cluster percolation and dynamical scaling in the Baxter--Wu model
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arXiv:2510.15124v2 Announce Type: replace-cross Abstract: We investigate the percolation behavior of Fortuin-Kasteleyn--type clusters in the spin-$1/2$ Baxter--Wu model with three-spin interactions on a triangular lattice. The considered clusters are constructed by randomly freezing one of the three sublattices, resulting in effective pairwise interactions among the remaining spins. Using Monte Carlo simulations combined with a finite-size scaling analysis, we determine the percolation temperature of these stochastic clusters and show that it coincides with the exact thermal critical point of the model. The critical exponents derived from cluster observables are consistent with those of the underlying thermal phase transition. Finally, we analyze the dynamical scaling of the multi-cluster and single-cluster algorithms resulting from the cluster construction, highlighting their efficiency and scaling behavior with system size.
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https://arxiv.org/abs/2510.15124
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0bd73922c6d7ff963e66681a7c921692bf26cb734c55fe8e840cd6e5e82190b9
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2026-01-07T00:00:00-05:00
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Excitation of Inertial Modes in 3D Simulations of Rotating Convection in Planets and Stars
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arXiv:2511.16630v2 Announce Type: replace-cross Abstract: Thermal convection in rotating stars and planets drives anisotropic turbulence and differential rotation, both capable of feeding energy into global oscillations. Using 3D simulations of rotating convection in spherical shells, we show that inertial modes--oscillations restored by the Coriolis force--emerge naturally in rotationally constrained turbulence, without imposing any external forcing other than thermal/buoyancy driving. By varying the rotation rate at fixed Rayleigh number, we find that coherent modes appear only when the convective Rossby number, the ratio of the rotation period to the convective turnover time, falls below about one-half, where rotation dominates the dynamics. These modes are mostly retrograde in the rotating frame, equatorially symmetric, and confined to mid and high latitudes, with discrete frequencies well below twice the background rotation rate. At lower viscosities, or smaller Prandtl number, mode excitation becomes more efficient and a broader spectrum of inertial modes emerges. While the precise excitation mechanism remains uncertain, our results suggest that the modes are driven by instabilities due to differential rotation rather than stochastic forcing by convection. We conclude that similar inertial modes are likely to exist in the interiors of giant planets and stars, though their low frequencies will make them difficult to detect.
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https://arxiv.org/abs/2511.16630
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49b56c7fc26ffd7487dbcf9e3b7754b2019f4ded4bf38f1190ed80b864116b2b
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2026-01-07T00:00:00-05:00
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Spaceflight KID Readout Electronics for PRIMA
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arXiv:2512.04816v2 Announce Type: replace-cross Abstract: We present the design and testing of a prototype multiplexing kinetic inductance detector (KID) readout electronics for the PRobe far-Infrared Mission for Astrophysics (PRIMA) space mission. PRIMA is a Probe-class astrophysics mission concept that will answer fundamental questions about the formation of planetary systems, the co-evolution of stars and supermassive black holes in galaxies, and the rise of heavy elements and dust over cosmic time. The readout electronics for PRIMA must be compatible with operation at Earth-Sun L2 and capable of multiplexing more than 1000 detectors over 2.5 GHz bandwidth while consuming around 30 W per readout chain. The electronics must also be capable of switching between the two instruments, which have different readout bands: the hyperspectral imager (PRIMAger, 2.6-4.9 GHz) and the spectrometer (FIRESS, 0.4-2.4 GHz). The PRIMA readout electronics use high-heritage SpaceCube digital electronics with a build-to-print SpaceCube Mini v3.0 board using a radiation-tolerant Kintex KU060 field programmable gate array (FPGA) and a custom high-speed digitizer board, along with RF electronics that provide filtering and power conditioning. We present the driving requirements for the system, as well as the hardware, firmware, software, and system-level design that meets those requirements.
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https://arxiv.org/abs/2512.04816
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f8e1a01f27ce0183208d611bedaa47126b9049d36ddc23aeaa31ac4a5d111ba0
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2026-01-07T00:00:00-05:00
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Photon blockade effect from synergistic optical parametric amplification and driving force in Kerr-medium single-mode cavity
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arXiv:2601.01819v2 Announce Type: replace-cross Abstract: This work investigates photon blockade control in a hybrid quantum system containing a Kerr-nonlinear cavity coupled to an optical parametric amplifier (OPA). The dynamics are governed by a master equation derived from an effective Hamiltonian that includes cavity decay. To obtain analytical solutions, the system's quantum state is expanded in the Fock basis up to the two-photon level. Solving the steady-state Schrodinger equation yields probability amplitudes and the analytical conditions for optimal photon blockade. Results confirm that photon blockade is achievable with suitable parameters. Excellent agreement is found between the analytical solutions and numerical simulations for the steady-state, equal-time second-order correlation function, validating both the analytical method and the blockade effect. Numerically, the average intracavity photon number increases significantly under resonance, providing a theoretical pathway for enhancing single-photon source brightness. Furthermore, the driving phase is shown to regulate the optimal blockade region: it shifts the parabolic region within the two-dimensional parameter space of driving strength and OPA nonlinearity and can even reverse its opening direction. The influence of Kerr nonlinearity is also examined. Photon blockade remains robust across a wide range of Kerr strengths. Physical analysis attributes the effect to destructive quantum interference between two distinct excitation pathways that suppress two-photon states. While Kerr nonlinearity shifts the system's energy levels, it does not disrupt this interference mechanism, explaining the effect's stability over a broad parameter range.
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https://arxiv.org/abs/2601.01819
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4ed2d305a53a8b1b72af36cf691e04e9d72694be7da9b53b34b31011d8cbd3e8
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2026-01-07T00:00:00-05:00
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Mean Field Variational Bayesian Inference and Statistical Mechanics of Gaussian Mixture Model
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arXiv:2601.02418v1 Announce Type: new Abstract: One of the main modeling in many data science applications is the Gaussian Mixture Model (GMM), and Mean Field Variational Bayesian Inference (MFVBI) is classically used for approximate fast computation. In this paper, we provide a definitive answer to the fundamental inquiry about the uncertainty quantification of the MFVBI applied to the GMM. It turns out that GMM can be considered as a generalization of Curie--Weiss model in statistical mechanics. The standard quantities like partition function and free energy appear naturally in the process of our analysis.
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https://arxiv.org/abs/2601.02418
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8905b8b1cbda6aef37436ad489b341a59c44676583badd184e879c139f1090f6
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2026-01-07T00:00:00-05:00
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An Analogue of Heyde's Theorem for Discrete Torsion Abelian Groups with Cyclic $p$-Components
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arXiv:2601.02489v1 Announce Type: new Abstract: According to the well-known Heyde theorem, the Gaussian distribution on the real line is characterized by the symmetry of the conditional distribution of one linear form of $n$ independent random variables given another. In the article, we prove an analogue of this theorem for two independent random variables taking values in a discrete torsion Abelian group $X$ with cyclic $p$-components. In doing so, we do not impose any restrictions on coefficients of the linear forms and the characteristic functions of random variables. The proof uses methods of abstract harmonic analysis and is based on the solution some functional equation on the character group of the group $X$.
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https://arxiv.org/abs/2601.02489
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1389a67a5cc96723a00eb3e9f3cba60f765b9cbe93eb49b0d4f35441d0f4eb8a
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2026-01-07T00:00:00-05:00
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Long Time Asymptotics for the Stochastic Follow-the-Leader System
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arXiv:2601.02501v1 Announce Type: new Abstract: We introduce and analyze a class of interacting particle systems on the real line that combine features of the stochastic rat race and (deterministic) follow-the-leader models. The particle system evolves as a continuous-time pure jump process: the leading particle moves independently, at Exponential jump times, with constant jump rate and iid jump sizes distributed according to a law $\theta$, while each of the remaining particles jumps forward, at Exponential times, at rate equal to its distance from the particle immediately ahead, with jump sizes drawn uniformly from the corresponding gap. The dynamics thus encode competition for leadership together with distance-dependent stochastic interactions. Our main focus is the associated gap process, representing the vector of inter-particle distances. We establish the existence of a unique stationary distribution for the gap process and prove uniform geometric ergodicity. Further, when the leader's jump sizes follow an Exponential distribution, we identify the stationary law explicitly as a product of independent Exponential laws, and show that the associated mixing time scales between $\Theta(n)$ and $O(n(\log n)^2)$ for an $n$-particle system. As an application of the mixing time results we establish a functional limit theorem that characterizes fluctuations of particle states at large time, under a suitable spatial and temporal scaling and large particle limit. Finally, when the leader's jumps have heavy but integrable tails, we show that each gap has at least one additional finite moment under stationarity than that of the leader's jump size distribution. The model offers a tractable setting for exploring ergodicity, explicit invariant laws, and mixing behavior in non-diffusive particle systems.
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https://arxiv.org/abs/2601.02501
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bc35e59ca2604f2fe243ea2f60ad6c02d1b645798ea1191af362aa2ae7840543
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2026-01-07T00:00:00-05:00
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Lagrangian slice disks with symplectomorphic exteriors
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arXiv:2601.02524v1 Announce Type: new Abstract: By modifying a construction of Abe and Tange, we exhibit arbitrarily large families of Lagrangian slice disks with Weinstein deformation equivalent exteriors. This answers a Lagrangian version of a question of Hitt and Sumners. We raise other open questions related to Lagrangian slice disks and their exteriors.
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https://arxiv.org/abs/2601.02524
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ee5645ec25ee061abc53929ca058150ac8715ca150cb9fb6aefeb18c8b743d63
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2026-01-07T00:00:00-05:00
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Lee-Yang phenomena in edge-coloured graph counting
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arXiv:2601.02525v1 Announce Type: new Abstract: We study the accumulation of zeros of a polynomial arising from the enumeration of edge-coloured graphs along certain limit curves. The polynomial is a variant of an edge-chromatic polynomial, which specialises to the partition function of the ferromagnetic Ising model on a random regular graph. We call this accumulation behaviour a Lee-Yang phenomenon in analogy with the Lee-Yang theorem. The limiting loci are semialgebraic and arise from anti-Stokes curves of an exponential integral.
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https://arxiv.org/abs/2601.02525
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66b46e47c18869490c58e2dfa3b57b77c2d5e9de6d2bffc7b73779a5b5b21b83
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2026-01-07T00:00:00-05:00
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H\"older estimates of weak solutions to chemotaxis systems of fast diffusion type
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arXiv:2601.02528v1 Announce Type: new Abstract: We study a quasilinear chemotaxis system of singular type, where the diffusion operator is given by $\Delta u^m$ with $0<1$, corresponding to the fast diffusion regime, and where the chemotactic drift is nonlinear. Since H\"older continuity constitutes the optimal regularity class for weak solutions to the porous medium equation, we establish analogous regularity results for bounded solutions of parabolic--parabolic chemotaxis systems in this setting. The proof is based on a refined De Giorgi--Di Benedetto iteration scheme adapted to the coupled structure of the system. These results advance the understanding of the fine regularity properties of chemotaxis models with nonlinear diffusion, and demonstrate that the interplay between singular diffusion and aggregation exhibits a regularizing mechanism consistent with the porous medium paradigm.
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https://arxiv.org/abs/2601.02528
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8323b9797e5114839debda27991dfbc9e8298154afb6fc01897ac34559b9aa10
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2026-01-07T00:00:00-05:00
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Affine mappings of translation surfaces: shrinking targets and Diophantine properties
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arXiv:2601.02541v1 Announce Type: new Abstract: Let $(X,\omega)$ be a translation surface whose Veech group $\Gamma$ is a lattice. We prove that the generic orbit of the group of affine homeomorphisms of $(X,\omega)$ can be used to approximate each point of $X$ with Diophantine precision. The proof utilizes an induced $SL_2(\mathbb{R})$-action on a fiber bundle $Y$ whose base is $SL_2(\mathbb{R})/\Gamma$ and whose fiber is $X$. We observe that this bundle embeds as an $SL_2(\mathbb{R})$-orbit closure in the moduli space of once marked translation surfaces, and hence we may invoke the spectral gap results of Avila and Gou\"ezel and a quantitative mean ergodic theorem for the $SL_2(\mathbb{R})$-action on the mean-zero, square-integrable functions on $Y$.
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https://arxiv.org/abs/2601.02541
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2824bb70db65b1d81f9fa852f59a36b0249ef327f5fd5953e68b87367d830dd3
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2026-01-07T00:00:00-05:00
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The fine spectral expansion of the Rankin-Selberg period
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arXiv:2601.02542v1 Announce Type: new Abstract: We state and prove the spectral expansion of the theta series attached to the Rankin-Selberg spherical variety $(\mathrm{GL}_{n+1} \times \mathrm{GL}_n)/\mathrm{GL}_n$. This is a key result towards the fine spectral expansion of the Jacquet-Rallis trace formula. Our expansion is written in terms of regularized Rankin--Selberg periods for non-tempered automorphic representations, which we show compute special values of $L$-functions. The proof relies on shifts of contours of integration \`a la Langlands. We also establish two technical but crucial results on bounds and singularities for discrete Eisenstein series of $\mathrm{GL}_n$ in the positive Weyl chamber.
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https://arxiv.org/abs/2601.02542
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54bf2eba673db9cb78453ae6f7007b6f77ae65d336d8c64246711ab0a5368713
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2026-01-07T00:00:00-05:00
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Construction of groups with triality and their corresponding code loops
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arXiv:2601.02546v1 Announce Type: new Abstract: We generalize the global construction of code loops introduced by Nagy, which is based on the connection between Moufang loops and groups with triality. This follows from the construction of a nilpotent group $G_n$ of class 3 with triality and $2n$ generators, based on embeddings of $G_n$ into direct products of copies of $G_3$. In the finite case, where $G_n$ is a group such that $|G_n| = 2^{4n+m}$ with $n \ge 3$ and $m = 3 {n \choose 2} + 2 {n \choose 3}$, we prove that the corresponding Moufang loop is the free loop $F_n$ with $n$ generators in the variety generated by code loops. The result depends on a construction similar to that of $G_n$, namely, embedding $F_n$ into direct products of copies of $F_3$, the free code loop associated with $G_3$.
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https://arxiv.org/abs/2601.02546
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7b19850b3e76e443f74c568f96cf306bb43f483d9705d13051f740ce202501ba
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2026-01-07T00:00:00-05:00
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Tree metrics and log-concavity for matroids
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arXiv:2601.02547v1 Announce Type: new Abstract: We show that a set function $\nu$ satisfies the gross substitutes property if and only if its homogeneous generating polynomial $Z_{q,\nu}$ is a Lorentzian polynomial for all positive $q \le 1$, answering a question of Eur-Huh. We achieve this by giving a rank 1 upper bound for the distance matrix of an ultrametric tree, refining a classical result of Graham-Pollak. This characterization enables us to resolve two open problems that strengthen Mason's log-concavity conjectures for the number of independent sets of a matroid: one posed by Giansiracusa-Rinc\'on-Schleis-Ulirsch for valuated matroids, and another posed by Pak for ordinary matroids.
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https://arxiv.org/abs/2601.02547
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41da4201134daba90464e03dcb61d6f00a267221cd5e331bfb33a72bb7cb5598
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2026-01-07T00:00:00-05:00
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Lamperti scaling for fractional Gaussian processes with non-stationary increments
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arXiv:2601.02558v1 Announce Type: new Abstract: The Lamperti transform offers a powerful bridge between self-similar processes and stationary dynamics, making it especially useful for analyzing anomalous diffusion models that lack stationary increments. In this paper we examine the Lamperti transforms of scaled sub-fractional and bi-fractional Brownian motions, deriving explicit covariance formulas, asymptotic behaviour, and precise exponential mixing rates. We also introduce Langevin type integral processes driven by these Gaussian fields, identify their self-similarity exponents, and show that their Lamperti images again form stationary Gaussian processes with rapid decorrelation. Through inverse Lamperti relations and Birkhoff's theorem, we establish rigorous single trajectory reconstruction of ensemble quantities for the original non-stationary processes. The results extend the scope of the scaled Lamperti framework to Gaussian processes with non-stationary increments and richer dependence structures.
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https://arxiv.org/abs/2601.02558
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f212a01a131899cf6f9baad6b7773b1ce391b13aa98f5035421d46299185fb24
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2026-01-07T00:00:00-05:00
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Travelling Waves in a Mathematical Model for Oncolytic Virotherapy
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arXiv:2601.02568v1 Announce Type: new Abstract: Oncolytic virotherapy (OVT) is a promising cancer treatment strategy in which engineered viruses selectively infect and destroy tumor cells. Motivated by the biological mechanisms underlying viral spread and tumor invasion into the tissue, we analyze a non-cooperative reaction-diffusion model capturing the invasion of tumor tissue by oncolytic viruses. Using carefully constructed upper and lower solutions together with Schauder's fixed point theorem, we establish the existence of positive travelling-wave solutions. In particular, we identify a minimal wave speed value $\bar c$ such that positive travelling waves exist for all $c \geq \bar c$ . Our analysis also highlights parameter regions where the existence of travelling waves remains ambiguous, suggesting new mathematical questions about the propagation of viral treatments through tumor environments.
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https://arxiv.org/abs/2601.02568
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432ac5d915789d9cfd2b7ff5f77c59b12c6a5a99a5ccb813c3e65b48b62c4e7f
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2026-01-07T00:00:00-05:00
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A modern perspective on Tutte's homotopy theorem
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arXiv:2601.02582v1 Announce Type: new Abstract: We begin with a review of Tutte's homotopy theory, which concerns the structure of certain graph associated to a matroid (together with some extra data). Concretely, Tutte's path theorem asserts that this graph is connected, and his homotopy theorem asserts that every cycle in the graph is a composition of ''elementary cycles'', which come in four different flavors. We present an extended version of the homotopy theorem, in which we give a more refined classification of the different types of elementary cycles. We explain in detail how the path theorem allows one to prove that the foundation of a matroid (in the sense of Baker--Lorscheid) is generated by universal cross-ratios, and how the extended homotopy theorem allows one to classify all algebraic relations between universal cross-ratios. The resulting ''fundamental presentation'' of the foundation was previously established in [Baker--Lorscheid], but the argument here is more self-contained. We then recall a few applications of the fundamental presentation to the representation theory of matroids. Finally, in the most novel but also the most speculative part of the paper, we discuss what a ''higher Tutte homotopy theorem'' might look like, and we present some preliminary computations along these lines.
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https://arxiv.org/abs/2601.02582
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ba3abdd0583a4cab392d2a18943e6372e10488fc56465c7d2c85414ee1c25358
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2026-01-07T00:00:00-05:00
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The fiber product of the Torelli map with any product $\mathcal{A}_{g_1}\times \dots \times \mathcal{A}_{g_k}\to\mathcal{A}_g$ is reduced
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arXiv:2601.02592v1 Announce Type: new Abstract: We prove that the fiber product of the Torelli map $t\colon \mathcal{M}^{ct}_g \to \mathcal{A}_g$ with any product $\mathcal{A}_{g_1}\times\dots\times \mathcal{A}_{g_k} \to \mathcal{A}_g$ for $g=g_1+\dots+g_k$ has a reduced scheme structure. As a consequence, letting $d=\text{codim}(t^*[\mathcal{A}_{g_1}\times\dots\times \mathcal{A}_{g_k}])$, we find that the class $t^*[\mathcal{A}_{g_1}\times\dots\times \mathcal{A}_{g_k}]\in \mathsf{CH}^{d}(\mathcal{M}^{ct}_g)$ is tautological. In particular, we obtain $t^*[\mathcal{A}_{g_1}\times\dots\times \mathcal{A}_{g_k}] = 0$ for $d > 2g-3.$
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https://arxiv.org/abs/2601.02592
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ab3d534616dd63b2213b2603a5da4aa0a2a66e8305b7c3cf783e1d7a8ce94c5c
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2026-01-07T00:00:00-05:00
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Antidiagonal Initial Complexes of Infinite Matrix Schubert Varieties are Cohen-Macaulay
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arXiv:2601.02612v1 Announce Type: new Abstract: We show that, under certain constraints, the Stanley-Reisner ring of an infinite simplicial complex is Cohen-Macaulay in the sense of ideals and weak Bourbaki unmixed. We apply this result to prove the wanted claim -- that initial complexes of matrix Schubert varieties corresponding to infinite permutations in $S_{\infty}$ with respect to an antidiagonal term order are Cohen-Macaulay (in the same sense), giving rise to new examples of non-Noetherian Cohen-Macaulay rings.
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https://arxiv.org/abs/2601.02612
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820194ae9a8ae906d9c9fa09e3cd7427b7ebe85749e06adc7ce3c54cb3e7b5ca
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2026-01-07T00:00:00-05:00
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A spectral product formula for repunits via a tridiagonal Toeplitz similarity
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arXiv:2601.02615v1 Announce Type: new Abstract: For $b>0$ and $n\geqslant 1$, we consider the $n\times n$ tridiagonal matrix $V_n(b)$ with diagonal entries $b+1$, superdiagonal entries $1$, and subdiagonal entries $b$. A diagonal similarity reduces $V_n(b)$ to a symmetric tridiagonal Toeplitz matrix and hence makes its spectrum explicit. Since $\det\left(V_n(b)\right)$ equals the geometric sum $1+b+\cdots+b^{n}$, taking determinants yields a finite cosine product evaluation for this quantity. As further consequences, we derive sharp bounds from the extremal eigenvalues, write down explicit eigenvectors with respect to a natural weighted inner product, and obtain a closed formula for $V_n(b)^{-1}$.
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https://arxiv.org/abs/2601.02615
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d219d59fcfe481bcc81afa93a10af3a0c726999ffa8a2eb9c3aa2d1522766b7b
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2026-01-07T00:00:00-05:00
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Mass splitting in the time-discrete generalized Euler equations and non-Monge solutions in multi-marginal optimal transport
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arXiv:2601.02616v1 Announce Type: new Abstract: The time-discretized, spatially continuous generalized Euler equations are a prototype example of multi-marginal optimal transport, yet the question whether they exhibit mass-splitting (or equivalently, whether they have solutions that are not of Monge form) has remained open. Here we resolve this question by giving a mass-splitting example in one spatial dimension. Moreover we present a related and very simple fully discrete example of mass-splitting which reveals a transparent underlying mechanism.
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https://arxiv.org/abs/2601.02616
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55e6a55d886b1961a48462e1a42443097a103d292a5571e074c7523ab858983a
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2026-01-07T00:00:00-05:00
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$K$-Bad Spheres
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arXiv:2601.02620v1 Announce Type: new Abstract: In this paper we look at the $E$-completion of topological spaces where $E$ is a $p$-local ring spectrum. After a brief review of the concept of $E$-completion, we specialize to the case where $E=K$, $p$-local complex periodic $K$-theory, and consider the $K$-theory of the unstable sphere $S^{2n+1}$. We show that for certain values of $n$ and an odd prime $p$, the $K$-homology of the $K$-completion is not isomorphic to the $K$-homology of the sphere itself, thus in the terminology of Bousfield and Kan, these spheres are '$K$-bad'.
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https://arxiv.org/abs/2601.02620
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72a7e26a4d742a35e017b4dff26ffe98267b09940e5e7972b64f52fcd703b28b
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2026-01-07T00:00:00-05:00
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Local Asymptotic Normality for Mixed Fractional Brownian Motion with $H>3/4$ Under High-Frequency Observation
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arXiv:2601.02622v1 Announce Type: new Abstract: In this paper we will consider the LAN property for both the Hurst parameter $H>3/4$ and the variance of the fractional Brownian motion plus an independent standard Brownian motion (called mixed fractional Brownian motion) with high-frequency observation. We will first remove the $H$-score linear term and orthogonalize the remainder through two non-diagonal transformations, then we can construct the CLT for the quadratic form base on $\| \cdot \|_{\mathrm{op}}/\|\cdot\|_F\to0$. At last we obtain a diagonal Gaussian LAN expansion with an explicit information matrix.
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https://arxiv.org/abs/2601.02622
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696a9337bb30a8027b5a0a37dc0120397cce982dcbef16f654f91b0efe5e0bba
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2026-01-07T00:00:00-05:00
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Joint extreme values of the Riemann zeta function at harmonic points
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arXiv:2601.02623v1 Announce Type: new Abstract: Using the resonance method, we obtain refined estimates for joint extreme values of the Riemann zeta function at harmonic points, improving upon Levinson's 1972 results and providing new insight into the behavior of the Riemann zeta function. Our proof is primarily based on Dirichlet series theory and the truncated Euler product for the Riemann zeta function. As a corollary, we can recover some previously known extreme value results for the zeta function.
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https://arxiv.org/abs/2601.02623
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2d194098444f7bb5def633818ec34ecda83c6a168351d9606260c03ee6fa243b
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2026-01-07T00:00:00-05:00
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New approach for elastic collisions with singular stress functions
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arXiv:2601.02639v1 Announce Type: new Abstract: A collision of a rubber rod to a hard floor is regarded as a simple example of obstacle problems for elastic material. In this article we have proposed a new mathematical model for the collision phenomenon by applying beam equations with singular stress functions, which is investigated in our recent works. As in the works we have established a mathematical method to deal with the singular stress function. Here, we demonstrate the validity of our modeling through observation to the numerical results. Also, we present existence and uniqueness results of the model given as initial boundary value problems.
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https://arxiv.org/abs/2601.02639
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4dba704b930978035d2f73dee98bb531e5dc84e7f5dd120299858905f61dc007
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2026-01-07T00:00:00-05:00
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Quasiconvexity in the Riemannian setting
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arXiv:2601.02642v1 Announce Type: new Abstract: We introduce a notion of quasiconvexity for continuous functions $f$ defined on the vector bundle of linear maps between the tangent spaces of a smooth Riemannian manifold $(M,g)$ and $\mathbb{R}^m$, naturally generalizing the classical Euclidean definition. We prove that this condition characterizes the sequential lower semicontinuity of the associated integral functional \[ F(u, \Omega) = \int_{\Omega} f(du) \, d\mu \] with respect to the weak$^*$ topology of $W^{1,\infty}(\Omega, \mathbb{R}^m)$, for every bounded open subset $\Omega\subseteq M$.
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https://arxiv.org/abs/2601.02642
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b4df3b61c4e78b810f889bdc3a2ce37501642b7a42f3627f455ee4d995674d0d
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2026-01-07T00:00:00-05:00
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Incubulable hyperbolic 3-pseudomanifold groups
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arXiv:2601.02655v1 Announce Type: new Abstract: We construct compact hyperbolic 3-manifolds with totally geodesic boundary, such that the closed 3-pseudomanifolds obtained by coning off the boundary components are negatively curved and contain locally convex subspaces whose fundamental groups have property (T). In particular, the fundamental groups of these 3-pseudomanifolds are word hyperbolic but not cubulable.
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https://arxiv.org/abs/2601.02655
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e3cae8d79aef1e3a47b1deb8c819d894d24885f3e6491d09c6e7033eba276ab7
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2026-01-07T00:00:00-05:00
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Powerful Fibonacci polynomials over finite fields
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arXiv:2601.02664v1 Announce Type: new Abstract: Bugeaud, Mignotte, and Siksek proved that the only perfect powers in Fibonacci sequence are 0, 1, 8, and 144. In this paper, we study the polynomial analogue of the problem. Especially, we give a complete characterization of the Fibonacci polynomials that are perfect powers or powerful over finite fields, where there are infinitely many of them. We also give similar characterizations for some of Horadam's generalized Lucas polynomial sequences, which include Fibonacci, Lucas, Chebyshev, and Jacobsthal polynomials.
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https://arxiv.org/abs/2601.02664
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e5c9454ebbb193653e2ee0faaa78742faf90b45793aa2ca05209cb717eefa048
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2026-01-07T00:00:00-05:00
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The weighted Forman and Lin-Lu-Yau Ricci flow on graphs
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arXiv:2601.02673v1 Announce Type: new Abstract: In this paper, we propose a type of Ricci flow on graphs where the probability distribution for the Lin-Lu-Yau curvature remains constant over time, and also study the related Forman curvature flow. These two curvature flows coincide on trees. We first prove the existence and uniqueness of solutions for both curvature flows in general graphs. Then, we obtain that the normalized curvature flow on trees converges to a constant curvature metric, and under the uniform measure, a complete classification of trees can be obtained based on the convergence results.
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https://arxiv.org/abs/2601.02673
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e4339dd59ae231506014cd5b4125c18a95f9031c625b61f469f7c01f42851e2b
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2026-01-07T00:00:00-05:00
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Revisiting a Fast Newton Solver for a 2-D Spectral Estimation Problem: Computations with the Full Hessian
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arXiv:2601.02690v1 Announce Type: new Abstract: Spectral estimation plays a fundamental role in frequency-domain identification and related signal processing problems. This paper revisits a 2-D spectral estimation problem formulated in terms of convex optimization. More precisely, we work with the dual optimization problem and show that the full Hessian of the dual function admits a Toeplitz-block Toeplitz structure which is consistent with our finding in a previous work. This particular structure of the Hessian enables a fast inversion algorithm in the solution of the dual optimization problem via Newton's method whose superior speed of convergence is illustrated via simulations.
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https://arxiv.org/abs/2601.02690
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b69b48be06292a431802395c929806a301ce7fb078586e8ea16ded24a9f0ee94
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2026-01-07T00:00:00-05:00
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A Classification of Fractal Squares
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arXiv:2601.02696v1 Announce Type: new Abstract: Let $\lambda_K:\bbR^2\rightarrow\{0,1,\ldots\}\cup\{\infty\}$ be the lambda function of a planar comapctum $K$, as defined in MR4488162. It is known that a planar continuum is locally connected if and only if its lambda function vanishes everywhere, or equivalently, $\lambda_K(K)=\{0\}$. In this article we show that every fractal square $K$ satisfies $\lambda_K(K)\subset\{0,1\}$ and find criterions to classify when $\lambda_K(K)$ equals $\{0\}$, $\{1\}$ or $\{0,1\}$. Here for any integer $N\ge2$ and any set $\Dc=\left\{(i,j): 0\le i,j\le N-1\right\}$ with cardinality $\ge2$, if we set $K^{(0)}=[0,1]^2$ and $\displaystyle K^{(n)}=\left\{\frac{x+d}{N}: x\in K^{(n-1)}, d\in\Dc\right\}(n\ge1)$ then $K=\bigcap_nK^{(n)}$ is called a fractal square.
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https://arxiv.org/abs/2601.02696
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3b1e25715a84ccb2467337ad62e6d2848640d215fc76e7ee0e718267fb71a72b
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2026-01-07T00:00:00-05:00
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Diffusion limit for the stationary distribution of a history-dependent two-level M/M/1 queue
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arXiv:2601.02705v1 Announce Type: new Abstract: Recently, Atar and Miyazawa [2] introduced a multi-level GI/G/1 queue with a finite number of levels, where both the arrival and service rates depend on the level corresponding to the current queue length. For this model, they proved that the diffusion limit of its queue length process in heavy traffic is the level-dependent reflected Brownian motion of [6]. In a subsequent study, Kobayashi et al. [4] derived the corresponding diffusion limit of the stationary distribution. These studies are motivated by the control of service capacity depending on the queue length. We are interested in the more general case where this control may also depend on the history of the queue length. As the first step toward such a generalization, we specialize the multi-level GI/G/1 queue to a two-level M/M/1 queue. We then extend the dynamics of this model so that its arrival and service rates depend not only on the current queue length but also on the recent history of queue lengths. Under the stability condition for this model, we first compute its stationary distribution in closed form, then derive its diffusion limit in heavy traffic. Finally, using this diffusion limit, we derive approximation formulas for the stationary distribution and then numerically assess their accuracy.
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https://arxiv.org/abs/2601.02705
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bb008429aca43e771e18071b4f97aa4897605098e3911ee67a460562faf809f9
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2026-01-07T00:00:00-05:00
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The Effective Ehrenpreis Conjecture
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arXiv:2601.02710v1 Announce Type: new Abstract: Let $M$ and $N$ be two closed hyperbolic Riemann surfaces. The Ehrenpreis Conjecture (proved by Kahn-Markovic) asserts that for any $\epsilon>0$ there are finite covers $M_\epsilon \to M$, and $N_\epsilon \to N$, such that the Teichmuller distance (in the suitable moduli space) between $M_\epsilon$ and $N_\epsilon$ is less than $\epsilon$. It is natural to ask how large the degrees of these coverings need to be to achieve that the distance between $M_\epsilon$ and $N_\epsilon$ is less than $\epsilon$. In this paper we show that there exists a constant $k>0$, depending only on $M$ and $N$, so that the covers $M_\epsilon \to M$, and $N_\epsilon \to N$, can be chosen to have the degrees less than $\epsilon^{-k}$. We show that this bound is optimal by considering the case when $M$ and $N$ are arithmetic Riemann surfaces with the same invariant trace field which are not commensurable to each other.
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https://arxiv.org/abs/2601.02710
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e03f6fd01cf3384030c14f8003e19ea9cde66465524dc65179e3f60519137e2c
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2026-01-07T00:00:00-05:00
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Symmetric quiver varieties and critical stable envelopes
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arXiv:2601.02719v1 Announce Type: new Abstract: Symmetric quiver varieties with potentials are natural generalizations of Nakajima quiver varieties, and their equivariant critical cohomologies provide more flexible settings for geometric representation theory and enumerative geometry. In this paper, we study their geometric properties and show that they behave like universally deformed Nakajima quiver varieties. Based on this, we provide a new proof of the existence of critical stable envelopes on them. Following an idea of Nakajima, we give a sheaf theoretic interpretation of critical stable envelopes by the hyperbolic restriction in the affinization of symmetric quiver varieties. The associativity of hyperbolic restrictions implies the triangle lemma of critical stable envelopes.
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https://arxiv.org/abs/2601.02719
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8e3d09e3df3a0791007674346207eb8a793fde7baa557dd57921f86373f3b62c
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2026-01-07T00:00:00-05:00
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Manifolds with harmonic curvature and curvature operator of the second kind
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arXiv:2601.02722v1 Announce Type: new Abstract: We prove that compact Riemannian manifolds of dimension $n\ge3$ with harmonic curvature and $\frac{n(n+2)}{2(n+1)}$-nonnegative curvature operator of the second kind must be Einstein. In particular, Building upon Dai-Fu's work \cite{DF}, it follows that if the curvature operator of the second kind is $\min\{\frac{n(n+2)}{2(n+1)},\max\{4,\frac{(n+2)}{4}\}\}$-nonnegative , then such a manifold must be of constant curvature.
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https://arxiv.org/abs/2601.02722
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e3ec310ccb0df00abf7693a36db4652fd89333a07ef3c0c83621147d8df80820
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2026-01-07T00:00:00-05:00
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Sampling non-log-concave densities via Hessian-free high-resolution dynamics
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arXiv:2601.02725v1 Announce Type: new Abstract: We study the problem of sampling from a target distribution $\pi(q)\propto e^{-U(q)}$ on $\mathbb{R}^d$, where $U$ can be non-convex, via the Hessian-free high-resolution (HFHR) dynamics, which is a second-order Langevin-type process that has $e^{-U(q)-\frac12|p|^2}$ as its unique invariant distribution, and it reduces to kinetic Langevin dynamics (KLD) as the resolution parameter $\alpha\to0$. The existing theory for HFHR dynamics in the literature is restricted to strongly-convex $U$, although numerical experiments are promising for non-convex settings as well. We focus on studying the convergence of HFHR dynamics when $U$ can be non-convex, which bridges a gap between theory and practice. Under a standard assumption of dissipativity and smoothness on $U$, we adopt the reflection/synchronous coupling method. This yields a Lyapunov-weighted Wasserstein distance in which the HFHR semigroup is exponentially contractive for all sufficiently small $\alpha>0$ whenever KLD is. We further show that, under an additional assumption that asymptotically $\nabla U$ has linear growth at infinity, the contraction rate for HFHR dynamics is strictly better than that of KLD, with an explicit gain. As a case study, we verify the assumptions and the resulting acceleration for three examples: a multi-well potential, Bayesian linear regression with $L^p$ regularizer and Bayesian binary classification. We conduct numerical experiments based on these examples, as well as an additional example of Bayesian logistic regression with real data processed by the neural networks, which illustrates the efficiency of the algorithms based on HFHR dynamics and verifies the acceleration and superior performance compared to KLD.
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https://arxiv.org/abs/2601.02725
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38c604aa1e0978765ddd4d83be39fb015f65b7306de1a575006fb292254bd308
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2026-01-07T00:00:00-05:00
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Remark about scalar curvature on certain noncompact manifolds
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arXiv:2601.02726v1 Announce Type: new Abstract: We give a sufficient condition to rule out complete Riemannian metrics with nonnegative scalar curvature on the interior of handlebodies. In higher dimensions, we give examples of ends of manifolds with positive scalar curvature metrics.
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https://arxiv.org/abs/2601.02726
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ef0850408cda98a03d3f6d09e1b36ae7a3abd02c892e305d4ff02f61ab8dc139
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2026-01-07T00:00:00-05:00
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Almost complex totally geodesic surfaces in the nearly K\"ahler $\frac{\text{SL}(3,\mathbb R)}{\mathbb R\times \text{SO}(2)}$
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arXiv:2601.02733v1 Announce Type: new Abstract: We give a detailed description of the nearly K\"ahler $\frac{\mathrm{SL}(3,\mathbb R)}{\mathbb R\times \mathrm{SO}(2)}$, which is one of the pseudo-Riemannian counterparts of the flag manifold $F(\mathbb{C}^3)$. The main result is the classification of totally geodesic almost complex surfaces in this space.
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https://arxiv.org/abs/2601.02733
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919d11340c5df0773c2628755e23e570d376d0525d081c4e65fb6dc523ecf882
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2026-01-07T00:00:00-05:00
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Stacks of p-adic shtukas and spatial kimberlites
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arXiv:2601.02741v1 Announce Type: new Abstract: The main purpose of this article is to show that the special Newton polygon map from the stack of p-adic shtukas to the stack of G-bundles on the Fargues--Fontaine curve is representable in diamonds and sufficiently nice for cohomological considerations (i.e. fdcs). The second purpose is to show that the $\bar{\mathbb{F}}_p$-fibers of the special Newton polygon map behave like formal schemes, and in particular, satisfy henselianity properties with respect to their reduced locus. These two goals achieved in this article are two of the crucial ingredients used in our collaboration with Hamman, Ivanov, Louren\c{c}o and Zou to construct the equivalence that compares the schematic and analytic local Langlands categories of Zhu and of Fargues--Scholze. To achieve these goals, we introduce and study spatial kimberlites, which is a better behaved variant of the theory previously developed by the author.
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https://arxiv.org/abs/2601.02741
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266518f7e6ff1425207af81234ee24f83f45b368a337310916b9289a50cf555f
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2026-01-07T00:00:00-05:00
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Generalized Double Duals of the Riemann Tensor in Geometry and Gravity
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arXiv:2601.02742v1 Announce Type: new Abstract: The Riemann curvature tensor fully encodes local geometry, but its Ricci contraction retains only limited information: only the Ricci tensor and the scalar curvature survive, while the Weyl curvature vanishes identically. We show that contracting instead the double dual of the Riemann tensor unlocks the full curvature structure, producing a canonical hierarchy of symmetric, divergence--free $(p,p)$ double forms. These tensors satisfy the first Bianchi identity and obey a hereditary contraction relation interpolating between the double dual tensor and the Einstein tensor. We prove that, in a generic geometric setting, each tensor in this hierarchy is the unique divergence--free $(p,p)$ double form depending linearly on the Riemann curvature tensor, thereby providing canonical higher--rank parents of the Einstein tensor. Their sectional curvatures coincide with the $p$--curvatures; notably, the $2$--curvature determines the full Riemann curvature tensor and forces the $\hat A$--genus of a compact spin manifold to vanish when nonnegative, a property not shared by Ricci or scalar curvature. Finally, we extend the construction to Gauss--Kronecker curvature tensors and Lovelock theory, showing in particular that the second Lovelock tensor $T_4$ admits a genuine four--index parent tensor.
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https://arxiv.org/abs/2601.02742
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Academic Papers
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f098cc2f8f7ca94e6dba8c68c3cf5d2b559becf033ee788266632dc002b72a27
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2026-01-07T00:00:00-05:00
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Counting Polynomial-type Exceptional Units on Algebraic Varieties over Number Fields
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arXiv:2601.02743v1 Announce Type: new Abstract: Previous research on exceptional units has primarily focused on the ring of rational integers or abstract finite rings, often restricted to linear or quadratic constraints. In this paper, we extend the concept of polynomial-type exceptional units to the ring of integers of an arbitrary algebraic number field. We investigate the number of these polynomial-type exceptional units on general algebraic varieties. By employing the Chinese Remainder Theorem and Hensel's lifting technique, we derive an exact counting formula for the number of these exceptional units on a smooth closed subscheme under the assumption of good reduction. Furthermore, using the Lang-Weil inequality, we establish an asymptotic estimate for the counting function. In particular, we prove that for varieties of degree at most two, the error term can be significantly improved, yielding a sharper asymptotic bound.
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https://arxiv.org/abs/2601.02743
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Academic Papers
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svg
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5b14000f4454969a73083a0b0d08a2c537ad9b00a32f92ce740218351ba32cd4
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2026-01-07T00:00:00-05:00
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Affirmative Results on a Conjecture on the Column Space of the Adjacency Matrix
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arXiv:2601.02746v1 Announce Type: new Abstract: The Akbari-Cameron-Khosrovshahi (ACK) conjecture, which appears to be unresolved, states that for any simple graph $G$ with at least one edge, there exists a nonzero {$\{0,1\}$}-vector in the row space of its adjacency matrix that is not a row of the matrix itself. In this talk, we present a unified framework that includes several families and operations of graphs that satisfy the ACK conjecture. Using these fundamental results, we introduce new graph constructions and demonstrate, through graph structural and linear algebraic arguments, that these constructions adhere to the conjecture. Further, we show that certain graph operations preserve the ACK property. These results collectively expand the known classes of graphs satisfying the conjecture and provide insight into its structural invariance under composition and extension.
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https://arxiv.org/abs/2601.02746
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Academic Papers
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svg
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7bd9f35bf35dd003c8b1ab57d447e1c7a587de5f383ed531fbf172e8850d44db
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2026-01-07T00:00:00-05:00
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Data-Driven Output-Based Approach to the Output Regulation Problem of Unknown Linear Systems via Value Iteration
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arXiv:2601.02748v1 Announce Type: new Abstract: The output regulation problem for unknown linear systems has been studied using state-based and output-based internal model approaches in the special case with no disturbances. This paper further investigates the output regulation problem for unknown linear systems using a data-driven output-based approach via value iteration. For this purpose, we first develop a novel output-feedback control law that does not explicitly rely on the observer gain to solve the output regulation problem. We then show that the data-driven approach for designing an output-feedback control law for the given plant can be reduced to the data-driven design of a state-feedback control law for a well-defined augmented auxiliary system. As a result, we develop a systematic data-driven approach to solve the output regulation problem for unknown linear systems via value iteration. Finally, we establish a relation between the data-driven state-feedback control law and the data-driven output-feedback control law in the LQR sense.
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https://arxiv.org/abs/2601.02748
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Academic Papers
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