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arXiv 2024年

作者： Cotrufo, Michele Esfahani, Sedigheh Korobkin, Dmitriy Alù, Andrea Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States The Institute of Optics University of Rochester RochesterNY14627 United States Physics Program Graduate Center of the City University of New York New YorkNY10016 United States

Nonlocal metasurfaces have recently enabled an ultra-compact, low-power and high-speed platform to perform analog image processing. While several computational tasks have been demonstrated based on this platform, most of the previous studies have focused only on spatial operations, such as spatial differentiation and edge detection. Here, we demonstrate that metasurfaces with temporal nonlocalities – that is, with a tailored dispersive response – can be used to implement time-domain signal processing in deeply subwavelength footprints. In particular, we show a passive metasurface performing first-order differentiation of an input signal with high-fidelity and high-efficiency. We also demonstrate that this approach is prone to scalability and cascaded computation. Our work paves the way to a new generation of ultra-compact, passive devices for all-optical computation, with applications in neural networks and neuromorphic computing. © 2024, CC BY.

关键词： Optical data processing

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Trapping of isotropic droplets by disclinations in nematic liquid crystals controlled by surface anchoring and elastic constant disparity

arXiv

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arXiv 2024年

作者： Haputhanthrige, Nilanthi P. Paladugu, Sathyanarayana Lavrentovich, Maxim O. Lavrentovich, Oleg D. Advanced Materials and Liquid Crystal Institute Kent State University KentOH44242 United States Department of Physics Kent State University KentOH44242 United States Department of Earth Environment and Physics Worcester State University WorcesterMA01602 United States Department of Physics and Astronomy University of Tennessee KnoxvilleTN37996 United States Materials Science Graduate Program Kent State University KentOH44242 United States

Linear defects such as dislocations and disclinations in ordered materials attract foreign particles since they replace strong elastic distortions at the defect cores. In this work, we explore the behavior of isotropic droplets nucleating at singular disclinations in a nematic liquid crystal, predesigned by surface photopatterning. Experiments show that in the biphasic nematic-isotropic region, although the droplets are attracted to the disclination cores, their centers of mass shift away from the core centers as the temperature increases. The shift is not random, being deterministically defined by the surrounding director field. The effect is explained by the balance of interfacial anchoring and bulk elasticity. An agreement with the experiment can be achieved only if the model accounts for the disparity of the nematic elastic constants;the so-called one-constant approximation, often used in the theoretical analysis of liquid crystals, produces qualitatively wrong predictions. In particular, the experimentally observed shift towards the bend region around a +1/2 disclination core can be explained only when the bend constant is larger than the splay constant. The described dependence of the precise location of a foreign inclusion at defect cores on the elastic and surface anchoring properties can be used in rational design of microscale architectures. © 2024, CC BY.

关键词： Nematic liquid crystals

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Terahertz spin dynamics in rare-earth orthoferrites

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Photonics Insights 2022年第2期1卷 1-56页

作者： Xinwei Li Dasom Kim Yincheng Liu Junichiro Kono Department of Physics California Institute of TechnologyPasadenaUSA Department of Electrical and Computer Engineering Rice UniversityHoustonUSA Applied Physics Graduate Program Smalley-Curl InstituteRice UniversityHoustonUSA Department of Physics and Astronomy Rice UniversityHoustonUSA Department of Materials Science and NanoEngineering Rice UniversityHoustonUSA

Recent interest in developing fast spintronic devices and laser-controllable magnetic solids has sparked tremendous experimental and theoretical efforts to understand and manipulate ultrafast dynamics in *** of spin dynamics in the terahertz(THz)frequency range are particularly important for elucidating microscopic pathways toward novel device ***,we review THz phenomena related to spin dynamics in rare-earth orthoferrites,a class of materials promising for antiferromagnetic *** expand this topic into a description of four key elements.(1)We start by describing THz spectroscopy of spin excitations for probing magnetic phase transitions in thermal *** acoustic magnons are useful indicators of spin reorientation transitions,electromagnons that arise from dynamic magnetoelectric couplings serve as a signature of inversion-symmetry-breaking phases at low temperatures.(2)We then review the strong laser driving scenario,where the system is excited far from equilibrium and thereby subject to modifications to the free-energy *** pathways for ultrafast laser manipulation of magnetic order are discussed.(3)Furthermore,we review a variety of protocols to manipulate coherent THz magnons in time and space,which are useful capabilities for antiferromagnetic spintronic applications.(4)Finally,new insights into the connection between dynamic magnetic coupling in condensed matter and the Dicke superradiant phase transition in quantum optics are *** presenting a review on an array of THz spin phenomena occurring in a single class of materials,we hope to trigger interdisciplinary efforts that actively seek connections between subfields of spintronics,which will facilitate the invention of new protocols of active spin control and quantum phase engineering.

关键词： terahertz spin dynamics magnetism orthoferrite ultrafast spectroscopy magneto-optics

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Design, Fabrication, and Testing of Stiffened Composite Panels with Acoustically Tailored Stiffeners 79

Design, Fabrication, and Testing of Stiffened Composite Pane...

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79th Vertical Flight Society Annual Forum and Technology Display, FORUM 2023

作者： Brown, Avery Moorhouse, Anna M. Bakis, Charles E. Smith, Edward C. Beck, Ben S. Shepherd, Micah R. Engineering Science and Mechanics Dept. Pennsylvania State Univ. University ParkPA United States Graduate Program in Acoustics Pennsylvania State Univ. University ParkPA United States Aerospace Engineering Dept. Pennsylvania State Univ. University ParkPA United States Engineering Acoustics Dept. Applied Research Laboratory State CollegePA United States Physics and Astronomy Dept. Brigham Young Univ. ProvoUT United States

ISBN: (纸本)9781713874799

Carbon fiber reinforced epoxy composites are being increasingly used for load bearing structural elements in large transport rotorcraft. However, due to the increased stiffness-to-density ratio of composites, problems associated with vibration and interior noise can be exacerbated by the use of composites in airframes. The current investigation explores the potential of optimized composite meta-structures to reduce vibration and interior noise in rotorcraft. The approach involves designing a taper into the thickness of blade stiffeners which, when combined with a limited amount of absorbing material in the thinned region, creates what is known as an "acoustic black hole" (ABH) in the stiffener. It is hypothesized that optimally designed ABH stiffeners can reduce broadband vibrations in stiffened panels. An optimization routine has been developed to determine the tradeoffs between vibration, mass, and buckling load due to compression parallel to the stiffeners. The tradeoffs are visualized using a 3-D Pareto front that helps the designer decide on the optimal design. Carbon/epoxy panels were made using vacuum-bag-oven processing with out-of-autoclave prepreg and verified to be of good quality. Panel vibration, buckling onset, and post-buckling load-deflection behavior were simulated using finite elements and measured using model testing and compression testing. Based on preliminary results, ABH-tapered stiffened panels have the ability to reduce radiated noise without a significant penalty in the mass and compressive load-bearing capability. Copyright © 2023 by the Vertical Flight Society. All rights reserved.

关键词： Optimal systems

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Carrollian c functions and flat space holographic RG flows in BMS3/CCFT2

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Physical Review D 2023年第12期108卷 126008-126008页

作者： Daniel Grumiller Max Riegler Institute for Theoretical Physics TU Wien Wiedner Hauptstrasse 8–10/136 A-1040 Vienna Austria Theoretical Sciences Visiting Program Okinawa Institute of Science and Technology Graduate University Onna 904-0495 Japan Quantum Technology Laboratories Clemens-Holzmeister-Straße 6/6 1100 Austria Vienna

We discuss c functions and their holographic counterpart for two-dimensional field theories with Carrollian conformal fixed points in the UV and the IR. Specifically, we construct asymptotically flat domain wall solutions of three-dimensional Einstein-dilaton gravity that model holographic renormalization group (RG) flows between BMS3 invariant UV and IR fixed points. We prove three theorems for such flows: (1) for every holographic RG flow in AdS3, there is a corresponding one in flat space, (2) the BMS central charge in the UV cannot be smaller than in the IR, and (3) the UV/IR ratio of Virasoro central charges is identical to the UV/IR ratio of corresponding BMS central charges. Finally, we tentatively propose a Casini–Huerta-like c functions for BMS3-invariant quantum field theories, inspired by the AdS3/CFT2 relation between monotonicity of the c function and the quantum null energy condition.

关键词： Conformal field theory Entanglement in field theory Gauge-gravity dualities Lower-dimensional field theories Quantum field theory

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Early and advanced crystallization stages in lithia-alumina-silica glasses nucleated by ZrO2

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Ceramics International 2025年

作者： Revelo, Raúl Julián Souza, Mauricio Lima Pena, Rafaella Bartz Yoshida, Satoshi Zanotto, Edgar Dutra Federal University of São Carlos Graduate Program in Materials Science and Engineering SP São Carlos13565-905 Brazil São Carlos Institute of Physics University of São Paulo SP São Carlos13566-590 Brazil Materials Integration Laboratories AGC Inc 1-1 Suehiro-Cho Tsurumi-Ku Kanagawa Yokohama230-0045 Japan

ZrO2 is one of the most effective and widely used nucleating agents in various families of glass-ceramics;however, its detailed mechanism remains a subject of debate. Understanding its nucleation mechanism requires a thorough analysis of microstructural evolution and the identification of factors influencing this process. This study investigates the effects of ZrO2 incorporation on the internal nucleation and microstructural evolution in stoichiometric LAS (Li2O·Al2O3·nSiO2) glass-ceramics of varying composition. Glasses with different SiO2 molar ratios (n = 2, 4, 5, and 6) were prepared with ZrO2 additions of 3.0 and 3.5 mol%. Several thermal treatments were employed, followed by characterization using XRD, SEM, STEM, and Raman spectroscopy. The results indicate that a minimum of 3.5 mol% ZrO2 is required to induce internal nucleation in LAS glasses with n = 4, 5, and 6. In these compositions, Zr-enriched regions formed through liquid-liquid phase separation serve as preferential sites for ZrO2 crystal precipitation, which subsequently induces the nucleation of β-quartz solid solution. Upon further treatment at higher temperatures, this metastable phase transforms into β-spodumene or its solid solution. As expected, increasing SiO2 content enhances glass network polymerization, as evidenced by the increased presence of Q3 species in Raman spectroscopy, leading to higher characteristic temperatures of glass transition and peak crystallization in DSC analyses. A higher SiO2 content results in fewer but larger crystals, whereas a lower SiO2 content promotes a higher number density of crystals within the glass matrix. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Glass ceramics

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Nanoslot-Induced Ultrastrong Phonon-Photon and Phonon-Phonon Coupling in Hybrid Organic-Inorganic Perovskites

Nanoslot-Induced Ultrastrong Phonon-Photon and Phonon-Phonon...

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Pacific Rim Conference on Lasers and Electro-Optics (CLEO/Pacific Rim)

作者： Dasom Kim Jin Hou Geon Lee Ayush Agrawal Sunghwan Kim Hao Zhang Di Bao Andrey Baydin Wenjing WU Fuyang Tay Shengxi Huang Daivd Hagenmüller Elbert E. M. Chia Dai-Sik Kim Minah Seo Aditya D. Mohite Junichiro Kono Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston TX USA Department of Electrical and Computer Engineering Rice University Houston TX USA Department of Materials Science and NanoEngineering Rice University Houston TX USA Sensor System Research Center Korea Institute of Science and Technology Seoul Republic of Korea Department of Physics and Astronomy Seoul National University Seoul Republic of Korea Department of Chemical and Biomolecular Engineering Rice University Houston TX USA Department of Physics Long-wavelength Nanotechnology Laboratory Quantum Photonics Institute Ulsan National Institute of Science and Technology (UNIST) Ulsan Republic of Korea Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore Smalley-Curl institute Rice University Houston TX USA CESQ-ISIS (UMR 7006) Universite de Strasbourg and CNRS Strasbourg France KU-KIST Graduate School of Converging Science and Technology Korea University Seoul Republic of Korea Department of Physics and Astronomy Rice University Houston TX USA

Methods for harnessing vibrational states are desired for phonon-based technologies. We realized ultrastrong coupling of two phonon modes in perovskite materials induced by ultrastrong coupling with a common photonic ... 详细信息

ISBN: (数字)9798350372076

ISBN: (纸本)9798350372083

关键词： Couplings Phonons Laser modes Perovskites Electro-optical waveguides Photonics

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Analysis and Design of Metasurface Antennas Based on Temporal Metastructures

Analysis and Design of Metasurface Antennas Based on Tempora...

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European Conference on Antennas and Propagation, EuCAP

作者： L. Stefanini D. Ramaccia M. Barbuto M. Karamirad M. Longhi A. Monti S. Vellucci A. Toscano A. Alù V. Galdi F. Bilotti “Roma Tre” University Rome Italy “Niccolò Cusano” University Rome Italy Photonics Initiative Advanced Science Research Center New York New York USA Physics Program Graduate Center City University of New York New York NY USA Department of Engineering University of Sannio Benevento BN Italy

In this contribution, we present the analysis and design of a novel class of metasurface-based antennas, whose radiative capabilities are enabled by temporal (time-switched) metamaterials. In particular, we consider a thin metasurface supporting the propagation of a surface wave that can switch instantaneously from a finite capacitive value of the surface impedance to an open circuit, resulting in a temporal interface. We demonstrate that after the temporal switch of the metasurface properties, the surface wave is instantaneously coupled to free space realizing a highly directive beam in end-fire direction. Thanks to wavenumber conservation across a temporal interface, we demonstrate that the proposed metasurface-based antenna can radiate at a much higher frequency with respect to the source frequency. Analytical formulations and numerical simulations are provided to predict and verify the frequency upshift and the radiation characteristics of the proposed novel antenna.

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Strong lensing of high-energy neutrinos

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Physical Review D 2023年第2期107卷 023011-023011页

作者： Yoon Chan Taak Tommaso Treu Yoshiyuki Inoue Alexander Kusenko Physics and Astronomy Department University of California Los Angeles California 90095-1547 USA Department of Earth and Space Science Graduate School of Science Osaka University 1-1 Machikaneyama Toyonaka Osaka 560-0043 Japan Interdisciplinary Theoretical and Mathematical Science Program (iTHEMS) RIKEN 2-1 Hirosawa Saitama 351-0198 Japan Kavli Institute for the Physics and Mathematics of the Universe (WPI) The University of Tokyo Institutes for Advanced Study The University of Tokyo 5-1-5 Kashiwanoha Kashiwa Chiba 277-8583 Japan Theoretical Physics Department CERN 1211 Geneva 23 Switzerland

We consider the effects of strong gravitational lensing by galaxy-scale deflectors on the observations of high-energy (E≫GeV) neutrinos (HENs). For HENs at cosmological distances, the optical depth for multiple imaging is ∼10−3, implying that while we do not expect any multiply imaged HENs with present samples, next-generation experiments should be able to detect the first such event. We then present the distribution of expected time delays to aid in the identification of such events, in combination with directional and energy information. In order to assist in the evaluation of HEN production mechanisms, we illustrate how lensing affects the observed number counts for a variety of intrinsic luminosity functions of the source population. Finally, we see that the lensing effects on the cosmic neutrino background flux calculation would be negligible by taking kiloparsec-scale jets as an example.

关键词： Gravitational lenses Astrophysical jets Galactic halos Galaxies Neutrinos Normal galaxies Astronomical masses & mass distributions Neutrino detectors

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Polarimetric Study of GRS 1915+105: Estimation of Interstellar Polarization Component

arXiv

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arXiv 2025年

作者： Inokuchi, Jin Kawabata, Koji S. Uemura, Makoto Hiraga, Hiroyuki Hiroshima University High School Fukuyama 5-14-1 Kasuga-cho Fukuyama Hiroshima721-8551 Japan Hiroshima Astrophysical Science Center Hiroshima University 1-3-1 Kagamiyama Hiroshima Higashi-Hiroshima739-8526 Japan Physics Program Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Hiroshima Higashi-Hiroshima739-8526 Japan

GRS 1915+105 is a well-known X-ray binary system composed of a black hole with a low-mass companion star and is recognized for emitting relativistic jets. Imazato et al. (2021) performed extensive polarimetry in a near-infrared (NIR) Ks band from 2019 April through December when GRS 1915+105 experienced an X-ray low luminous state and found almost stable polarization of PP = 2.42% ± 0.08%. We performed NIR polarimetry of the field stars around GRS 1915+105 in 2023 April and October, and found that the field stars that are not listed in Gaia DR3 and StarHorse2 catalogues show well aligned polarization that is consistent with GRS 1915+105's polarization. Those suggest that the interstellar clouds existing beyond 4 kpc causes the large interstellar extinction and that the polarization the GRS 1915+105 is mostly originated from the magnetically aligned dust grains within the clouds. Therefore, the jet-origin synchrotron radiation polarization would have given only minor contribution in the NIR band in 2019 Apr-Dec. © 2025, CC BY.

关键词： Infrared devices

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