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arXiv 2024年

作者： Venkatesan, Balaji Guan, Syu-You Chang, Jen-Te Chiu, Shiang-Bin Yang, Po-Yuan Su, Chih-Chuan Chang, Tay-Rong Raju, Kalaivanan Sankar, Raman Fongchaiya, Somboon Chu, Ming-Wen Chang, Chia-Seng Chang, Guoqing Lin, Hsin Del Maestro, Adrian Kao, Ying-Jer Chuang, Tien-Ming Department of Physics National Taiwan University Taipei10617 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica National Taiwan University Taipei11529 Taiwan Institute of Physics Academia Sinica Taipei11529 Taiwan Department of Physics National Cheng-Kung University Tainan701 Taiwan Center for Condensed Matter Sciences National Taiwan University Taipei10617 Taiwan Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei11529 Taiwan Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link 637371 Singapore Department of Physics and Astronomy University of Tennessee KnoxvilleTN37996 United States Institute for Advanced Materials & Manufacturing University of Tennessee KnoxvilleTN37996 United States Min H. Kao Department of Electrical Engineering and Computer Science University of Tennessee KnoxvilleTN37996 United States Center for Quantum Science and Technology National Taiwan University Taipei10607 Taiwan

Electronic liquid crystal (ELC) phases are spontaneous symmetry breaking states believed to arise from strong electron correlation in quantum materials such as cuprates and iron pnictides. Here, we report a direct observation of a smectic phase in a weakly correlated Dirac nodal line (DNL) semimetal GdSbxTe2-x. Incommensurate smectic charge modulation and intense local unidirectional nanostructure are visualized by using spectroscopic imaging - scanning tunneling microscopy. As topological materials with symmetry protected Dirac or Weyl fermions are mostly weakly correlated, the discovery of such an ELC phase are anomalous and raise questions on the origin of their emergence. Specifically, we demonstrate how chemical substitution generates these symmetry breaking phases before the system undergoes a charge density wave (CDW) - orthorhombic structural transition. Our results highlight the importance of impurities in realizing ELC phases and present a new material platform for exploring the interplay among quenched disorder, topology and electron correlation. Copyright © 2024, The Authors. All rights reserved.

关键词： Charge density waves

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!MESS: A modular, efficient speaker verification system

!MESS: A modular, efficient speaker verification system

引用

Workshop on Speaker Recognition and its Commercial and Forensic Applications, RLA2C 1998

作者： van Vuuren, Sarel Hermansky, Hynek Department of Electrical and Computer Engineering Oregon Graduate Institute of Science and Technology PO Box 91000 PortlandOR97291-1000 United States International Computer Science Institute BerkeleyCA United States

We describe a text-independent speaker verification system !MESS that was designed to be highly modular and efficient. The system incorporates an extension of the Tel script language that facilitates rapid prototyping and high overall execution speed. We provide an overview of the system and its implementation, detailing its applicability as a flexible research environment. Using the system we investigate the importance of parts of the modulation spectrum for speaker verification. We find that higher modulation frequencies are not particularly important for verification - removing them improves verification performance. On the 1997 Switchboard evaluation set, for test segments of 30 seconds, a relatively small system with lowpass filtering at 10Hz cutoff gives a 12% reduction in EER. Copyright © RLA2C 1998 - Speaker Recognition and its Commercial and Forensic *** rights reserved.

关键词： Low pass filters

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Channel Modeling for Ultraviolet Non-Line-of-Sight Communications Incorporating an Obstacle

Channel Modeling for Ultraviolet Non-Line-of-Sight Communica...

引用

IEEE Conference on Global Communications (GLOBECOM)

作者： Tianfeng Wu Fang Yang Tian Cao Ling Cheng Yupeng Chen Jian Song Julian Cheng Zhu Han Department of Electronic Engineering Beijing National Research Center for Information Science and Technology Tsinghua University Beijing P. R. China School of Telecommunications Engineering Xidian University Xi’an P. R. China School of Electrical and Information Engineering University of the Witwatersrand Johannesburg South Africa School of Microelectronics Southern University of Science and Technology Shenzhen P. R. China Shenzhen International Graduate School Tsinghua University Shenzhen P. R. China School of Engineering The University of British Columbia Kelowna Canada Department of Electrical and Computer Engineering University of Houston Houston TX USA

ISBN: (数字)9798350351255

ISBN: (纸本)9798350351262

Existing studies on ultraviolet (UV) non-line-of-sight (NLoS) channel modeling primarily focus on scenarios without any obstacle, which makes them unsuitable for small transceiver elevation angles in most cases. To address this issue, a UV NLoS channel model incorporating an obstacle was investigated in this paper, where the impacts of atmospheric scattering and obstacle reflection on UV signals were both taken into account. To validate the proposed model, we compared it to the related Monte-Carlo photon-tracing (MCPT) model that had been verified by outdoor experiments. Numerical results manifest that the path loss curves obtained by the proposed model agree well with those determined by the MCPT model, while its computation complexity is lower than that of the MCPT model. This work discloses that obstacle reflection can effectively reduce the channel path loss of UV NLoS communication systems.

关键词： Monte Carlo methods Atmospheric modeling Computational modeling Scattering Reflection Transceivers Numerical models Channel models Global communication Photonics

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Channel Modeling for Ultraviolet Non-Line-of-Sight Communications Incorporating an Obstacle

arXiv

引用

arXiv 2024年

作者： Wu, Tianfeng Yang, Fang Cao, Tian Cheng, Ling Chen, Yupeng Song, Jian Cheng, Julian Han, Zhu Department of Electronic Engineering Beijing National Research Center for Information Science and Technology Tsinghua University Beijing100084 China School of Telecommunications Engineering Xidian University Xi’an710071 China School of Electrical and Information Engineering University of the Witwatersrand Johannesburg2000 South Africa School of Microelectronics Southern University of Science and Technology Shenzhen518055 China Shenzhen International Graduate School Tsinghua University Shenzhen518055 China School of Engineering The University of British Columbia KelownaBCV1V 1V7 Canada Department of Electrical and Computer Engineering University of Houston HoustonTX77004 United States

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Near-field microwave microscopy of nanostructured materials: Modeling and experiment

Near-field microwave microscopy of nanostructured materials:...

引用

Low-Dimensional Materials and Devices 2021

作者： Lopez, Diego C. Ohlberg, Douglas A. A. Giraldo, Brian Ramirez, Jhonattan C. Kobayashi, Nobuhiko P. Do Rego, Cássio G. Medeiros-Ribeiro, Gilberto Electrical Engineering Graduate Program Universidade Federal de Minas Gerais Belo HorizonteMG 31270-901 Brazil Microscopy Center Universidade Federal de Minas Gerais Belo HorizonteMG 31270-901 Brazil Department of Electrical and Computer Engineering Baskin School of Engineering University of California Santa Cruz Santa CruzCA95064 United States Computer Science Department Universidade Federal de Minas Gerais Belo HorizonteMG 31270-901 Brazil

ISBN: (数字)9781510644397

ISBN: (纸本)9781510644380

Synthesis of novel material often times requires novel analysis and characterization techniques. The possibility of combining sputtering (SPU) and Atomic Layer Deposition (ALD) in the same chamber, Sputtering Atomic Layer Augmented Deposition (SALAD), has produced interesting meta-dielectric nanocomposite systems that have unique optical and electronic properties, which may find novel applications [1]. Scanning Microwave Impedance Microscopy (sMIM) is a relatively novel characterization tool which permits assessment of local impedance. More recently, the utilization of microwaves in the near field regime has been an exciting topic in the field of high-resolution microscopy. We were able to demonstrate 1 nm resolution using scanning Microwave Impedance Microscopy (sMIM) where a spontaneously forming water meniscus concentrated the microwave fields in small regions [2]. Here we analyzed numerically sMIM with Finite Element Method (FEM) to investigate complex metal-dielectric structures created in a SALAD system. sMIM measurements provide information on both real and imaginary parts of the reflected microwave signal, which can be associated with the local conductivity and permittivity. Yet, these quantities can be influenced by the local topography, so extraction of the electronic contribution is a challenge. In this work, we perform tip-surface distance scans in order to gain a better understanding of the substrate response and compare with the FEM results. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Finite element method

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Performance Analysis and Optimization for Jammer-Aided Multi-Antenna UAV Covert Communication

arXiv

引用

arXiv 2022年

作者： Du, Hongyang Niyato, Dusit Xie, Yuan-Ai Cheng, Yanyu Kang, Jiawen Kim, Dong In The School of Computer Science and Engineering Energy Research Institute @ NTU Interdisciplinary Graduate Program Nanyang Technological University Singapore The School of Computer Science and Engineering Nanyang Technological University Singapore The Institute of Electrical Engineering Yanshan University Qinhuangdao066004 China Alibaba-NTU Singapore Joint Research Institute Nanyang Technological University Singapore639798 Singapore The Department of Electrical and Computer Engineering Sungkyunkwan University Suwon16419 Korea Republic of

Unmanned aerial vehicles (UAVs) have attracted a lot of research attention because of their high mobility and low cost in serving as temporary aerial base stations (BSs) and providing high data rates for next-generation communication networks. To protect user privacy while avoiding detection by a warden, we investigate a jammer-aided UAV covert communication system, which aims to maximize the user's covert rate with optimized transmit and jamming power. The UAV is equipped with multi-antennas to serve multi-users simultaneously and enhance the Quality of Service. By considering the general composite fading and shadowing channel models, we derive the exact probability density (PDF) and cumulative distribution functions (CDF) of the signal-to-interference-plus-noise ratio (SINR). The obtained PDF and CDF are used to derive the closed-form expressions for detection error probability and covert rate. Furthermore, the covert rate maximization problem is formulated as a Nash bargaining game, and the Nash bargaining solution (NBS) is introduced to investigate the negotiation among users. To solve the NBS, we propose two algorithms, i.e., particle swarm optimization-based and joint two-stage power allocation algorithms, to achieve covertness and high data rates under the warden's optimal detection threshold. All formulated problems are proven to be convex, and the complexity is analyzed. The numerical results are presented to verify the theoretical performance analysis and show the effectiveness and success of achieving the covert communication of our algorithms. © 2022, CC BY.

关键词： Unmanned aerial vehicles (UAV)

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Terahertz Magnetospectroscopy of Gadolinium Gallium Garnet in Fields up to 25 T

Terahertz Magnetospectroscopy of Gadolinium Gallium Garnet i...

引用

JSAP-OSA Joint Symposia, JSAP 2021

作者： Bao, J. Peraca, N. Marquez Tay, F. Kritzell, T.E. Li, X. Noe, G.T. Katayama, I. Takeda, J. Nojiri, H. Yamahara, H. Tabata, H. Baydin, A. Kono, J. Department of Physics and Astronomy Rice University HoustonTX United States Department of Electrical and Computer Engineering Rice University HoustonTX United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX United States Department of Physics Graduate School of Engineering Science Yokohama National University Yokohama Japan Institute for Materials Research Tohoku University Sendai Japan Department of Electrical Engineering and Information Systems Graduate School of Engineering University of Tokyo Japan Smalley-Curl Institute Rice University HoustonTX United States Department of Materials Science and NanoEngineering Rice University HoustonTX United States

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engineering the directionality of hot carrier tunneling in plasmonic tunneling structures

arXiv

引用

arXiv 2023年

作者： Abbasi, Mahdiyeh Liao, Shusen Zhu, Yunxuan Natelson, Douglas Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Astronomy Engineering Rice University HoustonTX77005 United States Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States

Tunneling metal-insulator-metal (MIM) junctions can exhibit an open-circuit photovoltage (OCPV) response under illumination that may be useful for photodetection. One mechanism for photovoltage generation is hot carrier tunneling, in which photoexcited carriers generate a net photocurrent that must be balanced by a drift current in the open-circuit configuration. We present experiments in electromigrated planar MIM structures, designed with asymmetric plasmonic properties using Au and Pt electrodes. Decay of optically excited local plasmonic modes preferentially creates hot carriers on the Au side of the junction, leading to a clear preferred directionality of the hot electron photocurrent and hence a preferred polarity of the resulting OCPV. In contrast, in an ensemble of symmetric devices constructed from only one Au, polarity of the OCPV has no preferred direction. Copyright © 2023, The Authors. All rights reserved.

关键词： Plasmonics

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Enhancing Security in SDN: Systematizing Attacks and Defenses from a Penetration Perspective

TechRxiv

引用

TechRxiv 2024年

作者： Kim, Jinwoo Seo, Minjae Lee, Seungsoo Nam, Jaehyun Yegneswaran, Vinod Porras, Phillip Gu, Guofei Shin, Seungwon The School of Software Kwangwoon University Seoul01897 Korea Republic of The Graduate School of Information Security KAIST Daejeon34141 Korea Republic of The Department of Computer Science and Engineering Incheon National University Incheon22012 Korea Republic of The Department of Computer Engineering Dankook University Gyeonggi-do Yongin16890 Korea Republic of SRI International Menlo ParkCA94025 United States Texas A&M University College StationTX77843 United States The School of Electrical Engineering KAIST Daejeon34141 Korea Republic of

Over the last 15 years, Software-Defined Networking (SDN) has gained widespread support from both research communities and the industry owing to its open nature and programmability. This paradigm empowers stakeholders, including researchers, practitioners, and developers, to craft innovative networking services using robust APIs and a global network view, free from reliance on vendor-dependent control planes. However, the flexible architecture of SDN has introduced a plethora of security challenges absent in traditional network environments. While many surveys have presented existing attacks, there has been a lack of systematization of attacks from a penetration perspective, which is crucial for understanding attacks and their root causes. This paper aims to analyze previous literature that has disclosed attack cases in SDN, scrutinizing their vulnerabilities, penetration routes, and root causes. Additionally, we provide an in-depth and comprehensive discussion of the underlying problems associated with these attacks and present defenses proposed by researchers to mitigate them, analyzing how the root causes are remedied. Through this study, we aim to illuminate existing security issues within the current SDN architecture, prompting a reevaluation of various security problems and providing a future research guideline for SDN security. © 2024, CC BY.

关键词： Network intrusion

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engineering Andreev Bound States for Thermal Sensing in Proximity Josephson Junctions

arXiv

引用

arXiv 2025年

作者： Jung, Woochan Arnault, Ethan G. Huang, Bevin Park, Jinho Jang, Seong Watanabe, Kenji Taniguchi, Takashi Englund, Dirk Fong, Kin Chung Lee, Gil-Ho Physics Department Pohang University of Science and Technology Pohang37673 Korea Republic of Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Intelligence Community Postdoctoral Research Fellowship Program Massachusetts Institute of Technology CambridgeMA02139 United States Department of Mechanical Engineering Columbia University New YorkNY10027 United States Research Center for Functional Materials National Institute for Materials Science Tsukuba Japan International Center for Materials Nanoarchitectonics National Institute for Materials Science Tsukuba Japan Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Department of Electrical and Computer Engineering Northeastern University BostonMA02115 United States Department of Physics Northeastern University BostonMA02115 United States Quantum Materials and Sensing Institute BurlingtonMA01803 United States

The thermal response of proximity Josephson junctions (JJs) is governed by the temperature (T)- dependent occupation of Andreev bound states (ABS), making them promising candidates for sensitive thermal detection. In this study, we systematically engineer ABS to enhance the thermal sensitivity of critical current (lc) of proximity JJs, quantified as |dlc/dT/| for threshold readout scheme and |dlc/***−1| for inductive readout scheme. Using a gate-tunable graphene-based JJ platform, we explore the impact of key parameters—including channel length, transparency, carrier density, and superconducting material—on the thermal response. Our results reveal that the proximity-induced superconducting gap plays a crucial role in optimizing thermal sensitivity. Notably, we see a maximum |dlc/***−1| value of 0.6 K−1 at low temperatures with titanium-based graphene JJs. By demonstrating a systematic approach to engineering ABS in proximity JJs, this work establishes a versatile framework for optimizing thermal sensors and advancing the study of ABS-mediated transport. © 2025, CC BY.

关键词： Superconducting materials

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