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Effect of Epsilon-Near-Zero Modes on the Casimir Interaction between Ultrathin Films

Physical Review Letters 2023年第19期130卷 196901-196901页

作者： Tao Gong Iñigo Liberal Benjamin Spreng Miguel Camacho Nader Engheta Jeremy N. Munday Department of Electrical and Computer Engineering University of California Davis California 95616 USA Department of Materials Science and Engineering University of California Davis California 95616 USA Institute of Smart Cities Public University of Navarre Pamplona Navarre 31006 Spain Department of Electronics and Electromagnetism University of Seville Sevilla Sevilla 41012 Spain Department of Electrical and Systems Engineering University of Pennsylvania Philadelphia Pennsylvania 19104 USA

Vacuum fluctuation-induced interactions between macroscopic metallic objects result in an attractive force between them, a phenomenon known as the Casimir effect. This force is the result of both plasmonic and photonic modes. For very thin films, field penetration through the films will modify the allowed modes. Here, we theoretically investigate the Casimir interaction between ultrathin films from the perspective of force distribution over real frequencies for the first time. Pronounced repulsive contributions to the force are found due to the highly confined and nearly dispersion-free epsilon-near-zero (ENZ) modes that only exist in ultrathin films. These contributions persistently occur around the ENZ frequency of the film irrespective of the interfilm separation. We further associate the ENZ modes with a striking thickness dependence of a proposed figure of merit (FOM) for conductive thin films, suggesting that the motion of objects induced by Casimir interactions is boosted for deeply nanoscale sizes. Our results shed light on the correlation between special electromagnetic modes and the vacuum fluctuation-induced force as well as the resulting mechanical properties of ultrathin ENZ materials, which may create new opportunities for engineering the motion of ultrasmall objects in nanomechanical systems.

关键词： Casimir effect Electromagnetic interactions Light-matter interaction Metamaterials Optical materials & elements

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Effects of Multifunctional Interlayers on the Performance of Perovskite Solar Cells

Effects of Multifunctional Interlayers on the Performance of...

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International Conference on electrical, computer and Communication engineering (ECCE)

作者： Md. Seium Mahtab Dipto Md Jahirul Islam Md Rejvi Kaysir Javid Atai Department of Materials Science and Engineering (MSE) Khulna University of Engineering & Technology (KUET) Khulna Bangladesh Department of Electrical and Electronic Engineering (EEE) Khulna University of Engineering & Technology (KUET) Khulna 9203 Bangladesh Department of Electrical and Computer Engineering Waterloo Institute for Nanotechnology University of Waterloo Waterloo ON Canada School of Electrical and Information Engineering The University of Sydney NSW Australia

The development of perovskite solar cell (PSC) is one of the major advances in photovoltaic technology in recent years due to its lower cost, simple fabrication process, lightweight, sustainability, and being environmentally friendly. However, the power conversion efficiency (PCE) of the conventional PSC is still lower for commercialization. The efficiency of PSC has increased from 5% to 25% within the past few years, where introducing interlayer shows a significant improvement in PCE. In this paper, we numerically investigate the effects of different combinations of interlayers on the performance of PSC using gpvdm simulation software. Three different PCEs of 28.08%, 17.89 % and 25.62 % are found for three different interlayer combinations i.e., (i) Model A (TIO 2 /PMMA), (ii) Model B (V 2 O 5 /PEDOTPSS) and (iii) Model C (P3HT/ spiroMeOTAD). Both optical and electrical characteristics of different interlayers-based PSCs are investigated by using the properties of different interlayer materials in the simulation. Additionally, the photon distribution, their absorption, and consequent charge carrier generation are investigated while modifying the layer thickness of each unit. This study could be helpful for optimizing the electron and hole transport materials-based interlayers of the PSC.

关键词： Photovoltaic cells Optical device fabrication Charge carrier processes Electron optics Perovskites Software Optical materials

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Measurement of Water Diffusion Coefficient in Cross-Linked Gelatins Using the Terahertz Time-Domain Spectroscopy Technique

Measurement of Water Diffusion Coefficient in Cross-Linked G...

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2024 Conference on Lasers and Electro-Optics, CLEO 2024

作者： Walden, D. Chakraborty, D. Cheng, J. Straksys, A. Stirke, A. Melo, W.C.M.A. Jukna, A. Komissarov, I. Sobolewski, Roman Department of Physics and Astronomy University of Rochester RochesterNY14627 United States Laboratory for Laser Energetics University of Rochester RochesterNY14623-1299 United States Materials Science Graduate Program University of Rochester RochesterNY14627 United States State Research Institute Center for Physical Sciences & Technology Vilnius Lithuania Department of Physics Vilnius Gediminas Technical University Vilnius Lithuania Department of Electrical and Computer Engineering University of Rochester RochesterNY14627 United States

A novel method has been developed to evaluate the water diffusion dynamics in gelatin-based gels, based on transient terahertz time-domain spectroscopy measurements. Such gels are widely used models for human skin. &#... 详细信息

ISBN: (纸本)9781957171395

关键词： Transient analysis

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A Dynamic Model for Pauses in the Synthesized Speech of Mathematical Expressions in MathML 22

A Dynamic Model for Pauses in the Synthesized Speech of Math...

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Proceedings of the 14th International Conference on Education Technology and computers

作者： Adriana Souza Diamantino Freitas Bahia Federal Institute of Education Science and Technology Brazil and Doctoral Program in Digital Media Faculty of Engineering Faculty of Engineering of University of Porto Portugal Department of Electrical and Computer Engineering Faculty of Engineering of University of Porto Portugal

ISBN: (纸本)9781450397766

Voice synthesizers still present several challenges in the speech of mathematical content, as spoken mathematics has quite peculiar rules. In the synthesized speech, pauses help blind and visually impaired students identify the limits of mathematical operators and subexpressions. However, most studies on pauses define them uniformly or use simple punctuation marks to force the synthesizer to introduce pauses in certain parts of the expression. Speech is a dynamic process and pauses in expressions also need to be dynamic to make the synthetic speech of expressions more natural, as this can help in memorizing this type of content. This work proposed a dynamic model of pauses for mathematical expressions. Collected math expressions spoken by teachers were used to create the model. These expressions were useful for identifying patterns and creating a linear regression model. Blind and visually impaired students evaluated the model. Some improvements were observed when we compared the synthesized mathematical expressions with the model and Audiomath, the parameter tool used in this study.

关键词： Accessibility Synthesized Speech Mathematics Visual Impairment

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Disentangled Motion Modeling for Video Frame Interpolation 39

Disentangled Motion Modeling for Video Frame Interpolation

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39th Annual AAAI Conference on Artificial Intelligence, AAAI 2025

作者： Lew, Jaihyun Choi, Jooyoung Shin, Chaehun Jung, Dahuin Yoon, Sungroh Interdisciplinary Program in AI Seoul National University Korea Republic of Department of Electrical and Computer Engineering Seoul National University Korea Republic of School of Computer Science and Engineering Soongsil University Korea Republic of AIIS ASRI and INMC Seoul National University Korea Republic of

ISBN: (纸本)157735897X

Video Frame Interpolation (VFI) aims to synthesize intermediate frames between existing frames to enhance visual smoothness and quality. Beyond the conventional methods based on the reconstruction loss, recent works have employed generative models for improved perceptual quality. However, they require complex training and large computational costs for pixel space modeling. In this paper, we introduce disentangled Motion Modeling (MoMo), a diffusion-based approach for VFI that enhances visual quality by focusing on intermediate motion modeling. We propose a disentangled two-stage training process. In the initial stage, frame synthesis and flow models are trained to generate accurate frames and flows optimal for synthesis. In the subsequent stage, we introduce a motion diffusion model, which incorporates our novel U-Net architecture specifically designed for optical flow, to generate bi-directional flows between frames. By learning the simpler low-frequency representation of motions, MoMo achieves superior perceptual quality with reduced computational demands compared to the generative modeling methods on the pixel space. MoMo surpasses state-of-the-art methods in perceptual metrics across various benchmarks, demonstrating its efficacy and efficiency in VFI. © 2025, Association for the Advancement of Artificial Intelligence (***). All rights reserved.

关键词： Interpolation

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Corner cutting connects chiral colorimetry to net electric flux in lossless all-dielectric metasurfaces

arXiv

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arXiv 2024年

作者： Haddadin, Zaid Nguyen, Anna M.Y. Poulikakos, Lisa V. Department of Electrical & Computer Engineering UC San Diego La Jolla CA92093-0021 United States Department of Mechanical & Aerospace Engineering UC San Diego La Jolla CA92093-0021 United States Program of Materials Science & Engineering UC San Diego La Jolla CA92093-0021 United States

All-dielectric metasurfaces can produce structural colors, but the most advantageous design criteria are still being investigated. This work numerically studies how the two-dimensional shape of nanoparticles affects the colorimetric response under circularly polarized light (CPL) to develop a sensor distinguishing CPL orientations. Using lossless dielectric materials (silicon nitride on silicon dioxide), we achieve far-field dichroism by modifying oblong nanoparticles into L-shaped structures through corner cuts. This design suppresses one electric dipole under CPL illumination, leading to differential colorimetric responses. We link these responses to a decoupling effect in the near-field net electric flux. Our findings provide design guidelines for all-dielectric, lossless colorimetric sensors of chiral light. Copyright © 2024, The Authors. All rights reserved.

关键词： Silicon nitride

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Measurement of Water Diffusion Coefficient in Cross-Linked Gelatins Using the Terahertz Time-Domain Spectroscopy Technique

Measurement of Water Diffusion Coefficient in Cross-Linked G...

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CLEO: Applications and Technology in CLEO 2024, CLEO: A and T 2024 - Part of Conference on Lasers and Electro-Optics

关键词： Terahertz spectroscopy

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Boxcar gating for time-resolved mid-infrared photothermal imaging of axon-bundle water boundaries

Boxcar gating for time-resolved mid-infrared photothermal im...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Panagis D. Samolis Xuedong Zhu Michelle Y. Sander Department of Electrical and Computer Engineering and BU Photonics Center Boston University Boston MA Department of Biomedical Engineering Boston University Boston Massachusetts USA Division of Materials Science and Engineering Boston University Brookline MA

Time-resolved mid-infrared photothermal imaging via boxcar gating is presented for the study of interface dynamics between axon bundles and the surrounding water.

ISBN: (纸本)9781957171258

Time-resolved mid-infrared photothermal imaging via boxcar gating is presented for the study of interface dynamics between axon bundles and the surrounding water.

关键词： Diode lasers Image stacking Infrared imaging Photothermal effects Quantum cascade semiconductor lasers Thermal effects

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Towards cross-modal causal structure and representation learning 2

Towards cross-modal causal structure and representation lear...

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2nd Machine Learning for Health Symposium, ML4H 2022

作者： Mao, Haiyi Liu, Hongfu Xiaotian Dou, Jason Benos, Panayiotis V. Joint CMU-Pitt PhD Program in Computational Biology University of Pittsburgh United States Michtom School of Computer Science Brandeis University United States Department of Electrical and Computer Engineering University of Pittsburgh United States Department of Epidemiology University of Florida United States

Does the SARS-CoV-2 virus cause patients' chest X-Rays ground-glass opacities? Does an IDH-mutation cause differences in patients' MRI images? Conventional causal discovery algorithms, although well developed to uncover the cause-effect relationships on structured data, cannot elucidate causal relations between unstructured images and structured scalar variables due to the complexity of the former. In this paper, we consider causal discovery between images and structured (scalar) variables. Specifically, we derive low dimensional image representations to analyze with structured variables. We propose a two-module amortized variational algorithm named Cross-Modal Variational Causal representation and structure Learning (CMCL). CMCL jointly learns identifiable representations given a set of independent structured variables and causal relations via formulating latent representations and structured variables into a direct acyclic graph. Moreover, we further enforce counterfactual invariance/variance onto representations. We demonstrate that CMCL outperforms other related methods on synthetic datasets and validate causal relations on semi-synthetic datasets by visualization. © 2022 P.N. Argaw, E. Healey & I.S. Kohane.

关键词： Coronavirus

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Ferromagnetism triggered by band tripling in ruthenate Sr4Ru3O10

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Physical Review B 2024年第15期110卷 155134页

作者： N. Watanabe S. Souma K. Nakayama K. Yamauchi J. F. Ribeiro Y. Wang Miho Kitamura Koji Horiba Hiroshi Kumigashira T. Oguchi Z. Q. Mao Y. P. Chen T. Sato Department of Physics Graduate School of Science Advanced Institute for Materials Research (WPI-AIMR) Center for Science and Innovation in Spintronics (CSIS) Precursory Research for Embryonic Science and Technology (PRESTO) Center for Spintronics Research Network (CSRN) School of Electrical and Computer Engineering and Birck Nanotechnology Center Department of Physics Institute of Materials Structure Science (QST) Sendai 980-8579 Japan Institute of Multidisciplinary Research for Advanced Materials (IMRAM) Department of Physics and Astronomy and Purdue Quantum Science and Engineering Institute International Center for Synchrotron Radiation Innovation Smart (SRIS) Mathematical Science Center for Co-creative Society (MathCCS)

Itinerant ferromagnetism is understood in terms of a quasiparticle picture with renormalized many-body effects. While the ferromagnetic ground state is destabilized by thermal and quantum fluctuations leading to exotic states such as unconventional superconductivity, how the quasiparticles evolve across the ferromagnetic transition is a target of intensive debate. Here, we present a type of ferromagnetic transition that is accompanied by a drastic reconstruction of quasiparticle spectrum in a layered ferromagnetic ruthenate, Sr4Ru3O10. Angle-resolved photoemission spectroscopy uncovered that the three-dimensional coherent states below the ferromagnetic transition temperature (TC) turn into two-dimensional incoherent electronic states slightly above TC characterized by the disappearance of trilayer band splitting, ferromagnetic exchange splitting, and long-lived quasiparticles. Our findings suggest that the electronic coherence strongly modifies the fermiology and magnetic order, pointing to an intriguing coupling between quasiparticles and magnetic properties.

关键词： Electronic structure Fermi surface Ferromagnetism Quasiparticles & collective excitations van Hove singularity Ruddlesden-Popper compounds Angle-resolved photoemission spectroscopy Density functional theory First-principles calculations

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