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arXiv 2025年

作者： Ghimire, Arjun Basnet, Bijaya Wang, Hao Guragain, Parikshit Baldwin, Alan Twieg, Robert Lavrentovich, Oleg D. Gleeson, James Jakli, Antal Sprunt, Samuel Department of Physics Kent State University KentOH44242 United States Materials Science Graduate Program and Advanced Materials Liquid Crystal Institute Kent State University KentOH44242 United States Advanced Materials and Liquid Crystal Institute Kent State University KentOH44242 United States Department of Chemistry Kent State University KentOH44242 United States

A dynamic light scattering study of director-layer fluctuations in the antiferroelectric smectic-ZA phase of the ferroelectric nematic liquid crystal DIO is reported. The dynamics are consistent with the distinctive feature of the ZA phase that the smectic layers form parallel to the axis of molecular orientational order (director). A model is developed to describe quantitatively the dispersion of the fluctuation relaxation rates. The model is based on a specialization of the elastic free energy density of the smectic-C phase to the case of 90◦ director tilt, a"first-order" approximation of the viscous stresses by their form for an incompressible uniaxial fluid, and a treatment of the effect of chevron layer structure that develops in planar sample cells due to temperature-dependent layer shrinkage, as documented in previous studies on DIO. From the modeling, the layer compression elastic constant is estimated to be ∼ 100 times lower in the smectic-ZA phase than in an ordinary smectic-A liquid crystal. Possible effects of the antiferroelectric layer polarization on the director splay elasticity and viscosity are described. The temperature dependencies of the splay, twist, and bend elastic constants and associated viscosities in the higher temperature nematic phase are also presented. © 2025, CC BY.

关键词： Viscosity

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Noncontextual ontological models of operational probabilistic theories

arXiv

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arXiv 2025年

作者： Soltani, Sina Erba, Marco Schmid, David Selby, John H. International Centre for Theory of Quantum Technologies Uniwersytet Gdański ul. Jana Bażyńskiego 1A Gdańsk80-309 Poland Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada Theoretical Sciences Visiting Program Okinawa Institute of Science and Technology Graduate University Onna904-0495 Japan

An experiment or theory is classically explainable if it can be reproduced by some noncontextual ontological model. In this work, we adapt the notion of ontological models and generalized noncontextuality so it applies to the framework of operational probabilistic theories (OPTs). A defining feature of quotiented OPTs, which sets them apart from the closely related framework of generalized probabilistic theories (GPTs), is their explicit specification of the structure of instruments, these being generalizations of quantum instruments (including nondestructive measurements);in particular, one needs to explicitly declare which collections of transformations constitute a valid instrument. We are particularly interested in strongly causal OPTs, in which the choice of a future instrument can be conditioned on a past measurement outcome. This instrument structure might seem to permit the possibility of a contextual kind of ontological representation, where the representation of a given transformation depends on which instrument it is considered a part of. However, we prove that this is not possible by showing that for strongly causal quotiented OPTs the structure of instruments does not allow for such a contextual ontological representation. It follows that ontological representations of strongly causal quotiented OPTs are entirely determined by their action on individual transformations, with no dependence on the structure of instruments. Copyright © 2025, The Authors. All rights reserved.

关键词： Quantum theory

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Evidence of a CP broken deconfined phase in 4D SU(2) Yang-Mills theory at θ = π from imaginary θ simulations

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Journal of High Energy physics 2025年第5期2025卷 1-28页

作者： Hirasawa, Mitsuaki Honda, Masazumi Matsumoto, Akira Nishimura, Jun Yosprakob, Atis Department of Physics University of Milano-Bicocca Piazza della Scienza 3 Milano I-20126 Italy Istituto Nazionale di Fisica Nucleare (INFN) Sezione di Milano-Bicocca Piazza della Scienza 3 Milano I-20126 Italy Yukawa Institute for Theoretical Physics Kyoto University Kitashirakawa Oiwakecho Sakyo-ku Kyoto 606-8502 Japan Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) RIKEN 2-1 Hirosawa Saitama Wako 351-0198 Japan Graduate School of Science and Engineering Saitama University 255 Shimo-Okubo Sakura-ku Saitama 338-8570 Japan KEK Theory Center High Energy Accelerator Research Organization (KEK) 1-1 Oho Ibaraki Tsukuba 305-0801 Japan Graduate Institute for Advanced Studies SOKENDAI 1-1 Oho Ibaraki Tsukuba 305-0801 Japan Department of Physics Niigata University 8050 Ikarashi 2-no-cho Nishi-ku Niigata 950-2181 Japan

The spontaneous breaking of CP symmetry in 4D SU(N) pure Yang-Mills theory at θ = π has recently attracted much attention in the context of the higher-form symmetry and the ’t Hooft anomaly matching condition. Here we use Monte Carlo simulations to study the N = 2 case, which is interesting since it is the case opposite to the large-N limit, where explicit calculations are available. In order to circumvent the severe sign problem due to the θ term for real θ, we first obtain results at imaginary θ, where the sign problem is absent, and make an analytic continuation to real θ. We use the stout smearing in defining the θ term in the action to be used in our simulations. Thus we obtain the expectation value of the topological charge and the deconfining temperature at θ = π, and provide evidence that the CP symmetry, which is spontaneously broken at low temperature, gets restored strictly above the deconfining temperature. This conclusion is consistent with the anomaly matching condition and yet differs from the prediction in the large-N limit. © The Author(s) 2025.

关键词： Lattice Quantum Field Theory Non-Zero Temperature and Density Spontaneous Symmetry Breaking

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Temporal refraction and reflection in modulated mechanical metabeams: theory and physical observation

arXiv

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arXiv 2025年

作者： Wang, Shaoyun Shao, Nan Chen, Hui Chen, Jiaji Qian, Honghua Wu, Qian Duan, Huiling Alù, Andrea Huang, Guoliang Department of Mechanical and Aerospace Engineering University of Missouri ColumbiaMO65211 United States Center for Mechanics Plus Under Extreme Environments School of Mechanical Engineering and Mechanics Ningbo University Ningbo315211 China Photonics Initiative Advanced Science Research Center City University of New York New YorkNY United States Physics Program Graduate Center City University of New York New YorkNY United States Department of Mechanics and Engineering Science College of Engineering Peking University Beijing100871 China

Wave reflection and refraction at a time interface follow different conservation laws compared to conventional scattering at a spatial interface. This study presents the experimental demonstration of refraction and reflection of flexural waves across a temporal boundary in a continuum-based mechanical metabeam, and unveils opportunities that emerge by tailoring temporal scattering phenomena for phononic applications. We observe these phenomena in an elastic beam attached to an array of piezoelectric patches that can vary in time the effective elastic properties of the beam. Frequency conversion and phase conjugation are observed upon a single temporal interface. These results are consistent with the temporal Snell’s law and Fresnel equations for temporal interfaces. Further, we illustrate the manipulation of amplitude and frequency spectra of flexural wave temporal refraction and reflection through multi-stepped temporal interfaces. Finally, by implementing a smooth time variation of wave impedance, we numerically and experimentally demonstrate the capabilities of the temporal metabeam to realize waveform morphing and information coding. Our findings lay the foundation for developing time-mechanical metamaterials and time-phononic crystals, offering new avenues for advanced phonon manipulation in both wave amplitude and frequency. © 2025, CC BY.

关键词： Phonons

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Gyromagnetic Angular Momentum Interconversion in Neutron Stars

arXiv

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arXiv 2025年

作者： Funaki, Hiroshi Sekino, Yuta Tajima, Hiroyuki Kisaka, Shota Yasutake, Nobutoshi Matsuo, Mamoru Kavli Institute for Theoretical Sciences University of Chinese Academy of Sciences Beijing100190 China RIKEN Saitama Wako351-0198 Japan Saitama Wako351-0198 Japan Saitama Wako351-0198 Japan Department of Physics School of Science The University of Tokyo Tokyo113-0033 Japan Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima739-8526 Japan 2-1-1 Shibazono Chiba Narashino275-0023 Japan Advanced Science Research Center Japan Atomic Energy Agency Tokai319-1195 Japan CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing100190 China Saitama Wako351-0198 Japan

We propose a novel mechanism for angular momentum (AM) exchange between the crust and core of a neutron star (NS) via the gyromagnetic effect. Using extended hydrodynamics, we model the star by incorporating macroscopic AM and microscopic AM originating from neutron orbital and spin AM. We reveal that macroscopic dynamics in the crust can inform microscopic AM in the core leading to neutron spin polarization, and offer alternative scenario of (anti-)glitches. This work highlights the overlooked multi-scale AM interconversions in NS physics, paving the way for gyromagnetic astrophysics. Copyright © 2025, The Authors. All rights reserved.

关键词： Spin polarization

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Computational design of serine hydrolases

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science (New York, N.Y.) 2025年第6744期388卷 eadu2454页

作者： Lauko, Anna Pellock, Samuel J. Sumida, Kiera H. Anishchenko, Ivan Juergens, David Ahern, Woody Jeung, Jihun Shida, Alexander F. Hunt, Andrew Kalvet, Indrek Norn, Christoffer Humphreys, Ian R. Jamieson, Cooper Krishna, Rohith Kipnis, Yakov Kang, Alex Brackenbrough, Evans Bera, Asim K. Sankaran, Banumathi Houk, K.N. Baker, David Department of Biochemistry University of Washington Seattle WA United States Institute for Protein Design University of Washington Seattle WA United States Graduate Program in Biological Physics Structure and Design University of Washington Seattle WA United States Department of Chemistry University of Washington Seattle WA United States Graduate Program in Molecular Engineering University of Washington Seattle WA United States Paul G. Allen School of Computer Science and Engineering University of Washington Seattle WA United States Medical Scientist Training Program University of Washington Seattle WA United States Howard Hughes Medical Institute University of Washington Seattle WA United States Department of Chemistry and Biochemistry University of California Los Angeles CA United States

The design of enzymes with complex active sites that mediate multistep reactions remains an outstanding challenge. With serine hydrolases as a model system, we combined the generative capabilities of RFdiffusion with an ensemble generation method for assessing active site preorganization at each step in the reaction to design enzymes starting from minimal active site descriptions. Experimental characterization revealed catalytic efficiencies (kcat/Km) up to 2.2 × 105 M-1 s-1 and crystal structures that closely match the design models (Cα root mean square deviations <1 angstrom). Selection for structural compatibility across the reaction coordinate enabled identification of new catalysts remove with five different folds distinct from those of natural serine hydrolases. Our de novo approach provides insight into the geometric basis of catalysis and a roadmap for designing enzymes that catalyze multistep transformations.

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Active modulation of plasmonic signal with a subwavelength metal/nonlinear dielectric material/metal structure

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Chinese Optics Letters 2010年第6期8卷 584-587页

作者：王小蕾王沛陈春翀陈俊学鲁拥华明海詹其文 Department of Physics Anhui Key Laboratory of Optoelectronic Science and TechnologyUniversity of Science and Technology of China Electro-Optics Graduate Program University of Dayton300 College ParkDaytonOH 45469USA

Light propagation through a metal/nonlinear dielectric material/metal（M-NL-M） structure is numerically *** design parameters of the M-NL-M structure are found with the waveguide theory so that the structure only supports the symmetric surface plasmon polaritons（SPP（0）） mode and the antisymmetric surface plasmon polaritons（SPP（1）） *** coupling between the two modes within the M-NL-M structure is *** controlling the propagation constants of the two modes with the intensity-dependent dielectric constant of the nonlinear Kerr material,an effective all-optical control of plasmonic signal modulator can be realized with this M-NL-M structure.

关键词： Modulation Phonons Photons Quantum theory Solids

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Ion-Implantation, Epilayer Growth, and Lift-Off of High-Quality Diamond Films

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Advanced Functional Materials 2025年

作者： Zhang, Xiang Pieshkov, Tymofii S. Chen, Di Nonis, Suresh Ngan, Kinfung Oliveira, Eliezer F. Gray, Tia Biswas, Abhijit Puthirath, Anand B. Pate, Bradford B. Garratt, Elias J. Birdwell, A. Glen Neupane, Mahesh R. Ivanov, Tony Sun, Shuo Vajtai, Robert Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Texas Center for Superconductivity University of Houston HoustonTX77204 United States JILA and Department of Physics University of Colorado BoulderCO80309 United States SP Bauru17033-360 Brazil Chemistry Division Naval Research Laboratory WashingtonDC20375 United States DEVCOM Army Research Laboratory RF Devices and Circuits AdelphiMD20783 United States

The development of high-quality diamond films is pivotal for driving advances in quantum technology, power electronics, and thermal management. The ion implantation and lift-off technique has emerged as a crucial method for fabricating diamond films with controlled thickness and scalable production of large-area diamond wafers. This study advances the understanding of critical interface dynamics during diamond epilayer growth on ion-implanted commercial diamond substrates. Leveraging high-resolution cross-sectional electron microscopy and spectroscopic analyses, the direct transformation of the damaged diamond layer is revealed into a graphitic layer during epilayer overgrowth, eliminating the need for high-temperature annealing. Raman and photoluminescence spectroscopy mappings along the side section highlight the exceptional quality and purity of the epilayer, showcasing nitrogen-vacancy center densities comparable to electronic-grade diamond, making it highly suitable for quantum and electronic applications. Finally, the epilayer detaches efficiently via electrochemical etching, leaving a substrate with low surface roughness that is reusable for multiple growth cycles. These results provide valuable insights into refining the ion implantation and lift-off process, bridging critical gaps in interface evolution, and establishing a foundation for sustainable, high-performance diamond films across diverse technological applications. © 2025 Wiley-VCH GmbH.

关键词： Photoluminescence spectroscopy

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Ultrafast carrier dynamics and layer-dependent carrier recombination rate in InSe

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Nanoscale 2023年第7期15卷 3169-3176页

作者： Wu, Ting-Hsuan Cheng, Hao-Yu Lai, Wei-Chiao Sankar, Raman Chang, Chia-Seng Lin, Kung-Hsuan Department of Physics National Taiwan University Taipei106319 Taiwan Institute of Physics Academia Sinica Taipei115201 Taiwan Nano-Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei115201 Taiwan

InSe layered semiconductors with high mobility have advantages over transition-metal dichalcogenides in certain device applications. Understanding the dynamics of carriers, especially around the major bandgaps, is not only of fundamental interest but also important for improving the performance of devices. We investigated ultrafast carrier dynamics in exfoliated InSe near the bandgap and found that the presence of photocarriers led to shrinkage in the optical bandgap. In addition, we observed that the carrier recombination rate increased when the thickness of the InSe nanoflakes was reduced and the process was dominated by surface recombination. For the same flakes, the recombination rate became lower after the freshly exfoliated InSe was exposed to air and oxidized. Using a free carrier diffusion model, layer-dependent surface recombination velocities were obtained. Our investigation reveals that the surface condition and the thickness of few-layer InSe play important roles in carrier lifetimes. © 2023 The Royal Society of Chemistry.

关键词： Energy gap

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Enhancing Diagnostic Accuracy for Knee Osteoarthritis Using a Deep Learning Approach

Enhancing Diagnostic Accuracy for Knee Osteoarthritis Using ...

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International Symposium on Applied science 2024, ISAS 2024

作者： Raza, Aquib Ching, Congo Tak Shing Liu, Peng-Ta Phan, Thien-Luan Tran, Ngoc-Luan Nguyen, Ha Anh T. Rameez, Mohammad Li, Hung-Chung Linh, Dao Nguyen Phuong Van Hieu, Nguyen Tran, Trung Nghia National Taiwan University Taipei City10673 Taiwan Research Center for Information Technology Academia Sinica Taipei City11529 Taiwan Graduate Institute of Biomedical Engineering National Chung Hsing University Taichung402 Taiwan Department of Electrical Engineering National Chi Nan University Nantou County Taiwan Advanced Plant and Food Crop Biotechnology Center National Chung Hsing University Taichung402 Taiwan International Doctoral Program in Agriculture National Chung Hsing University Taichung402 Taiwan Fall Prevention Center Department of Physical Medicine & Rehabilitation Changhua Christian Hospital Changhua500 Taiwan Department of Physics and Electronic Engineering University of Science Vietnam National University - Ho Chi Minh City Ho Chi Minh City70000 Viet Nam Department of Computer Science University of York York HeslingtonYO10 5DD United Kingdom Undergraduate Program of Intellectual Creativity Engineering National Chung Hsing University Taichung402 Taiwan Ho Chi Minh City72409 Viet Nam HCMUT Vietnam National University Ho Chi Minh City Thu Duc Ho Chi Minh City71308 Viet Nam

This research introduces a deep learning framework that combines convolutional neural networks with autoencoders to improve the diagnostic accuracy of knee osteoarthritis. The study utilized a publicly available dataset from the Mendeley Data repository, where knee joint images were preprocessed using Contrast Limited Adaptive Histogram Equalization to enhance contrast and ensure consistent image sizing. Initially, an autoencoder was employed in an unsupervised manner to learn compressed representations of the data. These representations were then used to train a CNN to classify knee images into 'healthy' and 'osteoarthritic' categories. The model was trained using an 80:20 split for training and testing data, incorporating early stopping and data augmentation techniques to prevent overfitting and enhance generalization. Performance metrics such as accuracy, precision, recall, and the area under the Receiver Operating Characteristic curve (ROCAUC) were used to evaluate the model, resulting in a high test accuracy of 98.95%. The high precision and recall rates further confirmed the model's robustness in diagnosing KOA. To enhance interpretability, Gradient-weighted Class Activation Mapping (Grad-CAM) was applied to identify critical regions in the images that influenced the model's decisions. Additionally, t-Distributed Stochastic Neighbor Embedding (t-SNE) was used to visualize the high-dimensional encoded features in a two-dimensional space, providing deeper insights into how the model differentiates between classes. The promising results of this deep learning approach suggest its potential for broader applications in medical imaging diagnostics. By providing healthcare professionals with a tool that enhances diagnostic accuracy and operational efficiency, this framework lays the foundation for developing scalable, AI-driven diagnostic systems for various complex medical conditions. © 2025 Institute of physics Publishing. All rights reserved.

关键词： Joints (anatomy)

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