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arXiv 2017年

作者： Mahmood, Fahad Alpichshev, Zhanybek Lee, Yi-Hsien Kong, Jing Gedik, Nuh Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Materials Science and Engineering National Tsing-Hua University Hsinchu30013 Taiwan Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States

The valley pseudospin in monolayer transition metal dichalcogenides (TMDs) has been proposed as a new way to manipulate information in various optoelectronic devices. This relies on a large valley polarization that remains stable over long timescales (hundreds of ns). However, time resolved measurements report valley lifetimes of only a few ps. This has been attributed to mechanisms such as phonon-mediated inter-valley scattering and a precession of the valley psedospin through electron-hole exchange. Here we use transient spin grating to directly measure the valley depolarization lifetime in monolayer MoSe2. We find a fast valley decay rate that scales linearly with the excitation density at different temperatures. This establishes the presence of strong exciton-exciton Coulomb exchange interactions enhancing the valley depolarization. Our work highlights the microscopic processes inhibiting the efficient use of the exciton valley pseudospin in monolayer TMDs. Copyright © 2017, The Authors. All rights reserved.

关键词： Landforms

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Superconducting contact and quantum interference between two-dimensional van der Waals and three-dimensional conventional superconductors

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Physical Review materials 2021年第1期5卷 014001-014001页

作者： Michael R. Sinko Sergio C. de la Barrera Olivia Lanes Kenji Watanabe Takashi Taniguchi Susheng Tan David Pekker Michael Hatridge Benjamin M. Hunt Department of Physics Carnegie Mellon University Pittsburgh Pennsylvania 15213 USA Department of Physics and Astronomy University of Pittsburgh Pittsburgh Pennsylvania 15260 USA Advanced Materials Laboratory National Institute for Materials Science Tsukuba Ibaraki 305-0044 Japan Department of Electrical and Computer Engineering University of Pittsburgh Pittsburgh Pennsylvania 15260 USA Petersen Institute of Nanoscience and Engineering University of Pittsburgh Pittsburgh Pennsylvania 15260 USA

This paper is a contribution to the joint Physical Review Applied and Physical Review materials collection titled Two-Dimensional materials and Devices.

关键词： Josephson effect Superconductivity Interfaces Transition metal dichalcogenides

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Subwavelength-engineered Antislot Photonic Crystals in a Silicon Photonics Foundry for On-chip Communications

Subwavelength-engineered Antislot Photonic Crystals in a Sil...

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CLEO: science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

作者： Arnold, Kellen P. Allen, Joshua A. Halimi, Sami I. Ryder, Landen D. Afzal, Francis O. Bian, Yusheng Aboketaf, Abdelsalam Hirokawa, Takako Dezfulian, Kevin Rakowski, Michal Augur, Rod Nummy, Karen Weiss, Sharon M. Interdisciplinary Materials Science Program Vanderbilt University 2201 West End Ave NashvilleTN37235 United States Department of Electrical and Computer Engineering Vanderbilt University 2201 West End Ave NashvilleTN37235 United States NASA Goddard Space Flight Center Code 561 GreenbeltMD20771 United States GlobalFoundries 400 Stone Break Rd. Ext. MaltaNY12020 United States

We report scalable foundry fabrication and characterization of photonic crystal nanobeam waveguides incorporating subwavelength-scale dielectric antislot unit cells. This work enables enhanced light-matter interaction... 详细信息

关键词： Silicon photonics

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Recent Advances in Triboelectric Nanogenerators: From Technological Progress to Commercial Applications

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ACS Nano 2023年第12期17卷 11087-11219页

作者： Choi, Dongwhi Lee, Younghoon Lin, Zong-Hong Cho, Sumin Kim, Miso Ao, Chi Kit Soh, Siowling Sohn, Changwan Jeong, Chang Kyu Lee, Jeongwan Lee, Minbaek Lee, Seungah Ryu, Jungho Parashar, Parag Cho, Yujang Ahn, Jaewan Kim, Il-Doo Jiang, Feng Lee, Pooi See Khandelwal, Gaurav Kim, Sang-Jae Kim, Hyun Soo Song, Hyun-Cheol Kim, Minje Nah, Junghyo Kim, Wook Menge, Habtamu Gebeyehu Park, Yong Tae Xu, Wei Hao, Jianhua Park, Hyosik Lee, Ju-Hyuck Lee, Dong-Min Kim, Sang-Woo Park, Ji Young Zhang, Haixia Zi, Yunlong Guo, Ru Cheng, Jia Yang, Ze Xie, Yannan Lee, Sangmin Chung, Jihoon Oh, Il-Kwon Kim, Ji-Seok Cheng, Tinghai Gao, Qi Cheng, Gang Gu, Guangqin Shim, Minseob Jung, Jeehoon Yun, Changwoo Zhang, Chi Liu, Guoxu Chen, Yufeng Kim, Suhan Chen, Xiangyu Hu, Jun Pu, Xiong Guo, Zi Hao Wang, Xudong Chen, Jun Xiao, Xiao Xie, Xing Jarin, Mourin Zhang, Hulin Lai, Ying-Chih He, Tianyiyi Kim, Hakjeong Park, Inkyu Ahn, Junseong Huynh, Nghia Dinh Yang, Ya Wang, Zhong Lin Baik, Jeong Min Choi, Dukhyun Kyung Hee University Gyeonggi Yongin17104 Korea Republic of Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Department of Mechanical Engineering Soft Robotics Research Center Seoul National University Seoul08826 Korea Republic of Department of Mechanical Engineering Gachon University Seongnam13120 Korea Republic of Department of Biomedical Engineering National Taiwan University Taipei10617 Taiwan Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu30013 Taiwan School of Advanced Materials Science & Engineering Sungkyunkwan University Suwon16419 Korea Republic of Sungkyunkwan University 2066 Seobu-ro Gyeonggi Suwon16419 Korea Republic of Department of Chemical and Biomolecular Engineering National University of Singapore 4 Engineering Drive 4 117585 Singapore Division of Advanced Materials Engineering Jeonbuk National University 567 Baekje-daero Jeonbuk Jeonju54896 Korea Republic of Jeonbuk National University 567 Baekje-daero Jeonbuk Jeonju54896 Korea Republic of Department of Physics Inha University 100 Inha-ro Incheon22212 Korea Republic of School of Materials Science & Engineering Yeungnam University Gyeongbuk Gyeongsan38541 Korea Republic of 291 Daehak-ro Daejeon34141 Korea Republic of School of Materials Science and Engineering Nanyang Technological University 50 Nanyang Avenue 639798 Singapore Institute of Flexible Electronics Technology of Tsinghua Zhejiang Jiaxing314000 China Nanomaterials and System Lab Major of Mechatronics Engineering Faculty of Applied Energy System Jeju National University Jeju632-43 Korea Republic of School of Engineering University of Glasgow GlasgowG128QQ United Kingdom Seoul02792 Korea Republic of Department of Physics Inha University Incheon22212 Korea Republic of Suwon16419 Korea Republic of Department of

Serious climate changes and energy-related environmental problems are currently critical issues in the world. In order to reduce carbon emissions and save our environment, renewable energy harvesting technologies will serve as a key solution in the near future. Among them, triboelectric nanogenerators (TENGs), which is one of the most promising mechanical energy harvesters by means of contact electrification phenomenon, are explosively developing due to abundant wasting mechanical energy sources and a number of superior advantages in a wide availability and selection of materials, relatively simple device configurations, and low-cost processing. Significant experimental and theoretical efforts have been achieved toward understanding fundamental behaviors and a wide range of demonstrations since its report in 2012. As a result, considerable technological advancement has been exhibited and it advances the timeline of achievement in the proposed roadmap. Now, the technology has reached the stage of prototype development with verification of performance beyond the lab scale environment toward its commercialization. In this review, distinguished authors in the world worked together to summarize the state of the art in theory, materials, devices, systems, circuits, and applications in TENG fields. The great research achievements of researchers in this field around the world over the past decade are expected to play a major role in coming to fruition of unexpectedly accelerated technological advances over the next decade. © 2023 The Authors. Published by American Chemical Society

关键词： Nanogenerators

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Tuning light emission crossovers in atomic-scale aluminum plasmonic tunnel junctions

arXiv

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arXiv 2022年

作者： Zhu, Yunxuan Cui, Longji Abbasi, Mahdiyeh Natelson, Douglas Department of Physics and Astronomy Rice University HoustonTX77005 United States Paul M. Rady Department of Mechanical Engineering University of Colorado BoulderCO80309 United States Materials Science and Engineering Program University of Colorado BoulderCO80309 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States

Atomic sized plasmonic tunnel junctions are of fundamental interest, with great promise as the smallest on-chip light sources in various optoelectronic applications. Several mechanisms of light emission in electrically driven plasmonic tunnel junctions have been proposed, from single-electron or higher order multi-electron inelastic tunneling to recombination from a steady-state population of hot carriers. By progressively altering the tunneling conductance of an aluminum junction, we tune the dominant light emission mechanism through these possibilities for the first time, finding quantitative agreement with theory in each regime. Improved plasmonic resonances in the energy range of interest increase photon yields by two orders of magnitude. These results demonstrate that the dominant emission mechanism is set by a combination of tunneling rate, hot carrier relaxation timescales, and junction plasmonic properties. Copyright © 2022, The Authors. All rights reserved.

关键词： Tunnel junctions

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Flexible Polyolefin with Enhanced Dipolar Polarization for Energy Storage Capacitors

Flexible Polyolefin with Enhanced Dipolar Polarization for E...

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Conference on electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Jing Hao Irene Mutegi Jierui Zhou Omer Yassin Gregory A. Sotzing Yang Cao Electrical Insulation Research Center Institute of Materials Science University of Connecticut Storrs CT USA Institute of Materials Science University of Connecticut Storrs CT USA Department of Chemistry University of Connecticut Storrs CT USA Department of Electrical and Computer Engineering University of Connecticut Storrs CT US

Polymer dielectrics endowed with high dielectric constant and high breakdown strength are critical for high-power systems and compact electronics to realize ultrahigh energy density. Nevertheless, the constrained energy density attainment of prevalent commercial polymers such as BOPP has been impeded by their inadequately satisfied dielectric constant. A polynorbornenes-BP (PNB-BP) is introduced in this paper, which features a rigid backbone composed of bicyclic aliphatic, while the incorporation of an electron acceptor and aromatic groups facilitates the formation of an enhanced dipole, endowing it with a satisfied dielectric constant of 3.72. Leveraging its high breakdown strength, the PNB-BP polymer achieves a notable energy density of 12.7 J/cm 3 at room temperature. Furthermore, the PNB-BP polymer exhibits commendable thermal properties, including a high glass transition temperature (Tg) of 220°C, and satisfactory thermal stability as evidenced by the observed dielectric constants. The design strategy uncovered in this work unveils the to realize the ultrahigh energy density of the capacitor by introducing the enhanced dipole.

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Experimental Entanglement-Enhanced Covert Sensing

Experimental Entanglement-Enhanced Covert Sensing

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Conference on Lasers and Electro-Optics (CLEO)

作者： Shuhong Hao Haowei Shi Christos N. Gagatsos Mayank Mishra Boulat Bash Ivan Djordjevic Saikat Guha Quntao Zhuang Zheshen Zhang Department of Materials Science and Engineering University of Arizona Tucson Arizona USA James C. Wyant College of Optical Sciences University of Arizona Tucson Arizona USA Department of Electrical and Computer Engineering University of Arizona Tucson Arizona USA

We report the theory and experiment for entanglement-enhanced covert sensing, a paradigm that simultaneously offers high measurement precision and data integrity by concealing the execution of the protocol.

ISBN: (数字)9781957171050

ISBN: (纸本)9781665466660

关键词： Laser theory Protocols Quantum entanglement Data integrity Measurement by laser beam Lasers and electrooptics Optical sensors

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Curriculum-Based Reinforcement Learning for an Effective Multi-Agent Path Planning Algorithm in Warehouse Scenarios

Curriculum-Based Reinforcement Learning for an Effective Mul...

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IEEE/IAS International Conference on Industry Applications (INDUSCON)

作者： Iure Rosa L. De Oliveira Kevin B. De Carvalho Alexandre S. Brandão Graduate Program in Computer Science Universidade Federal de Viçosa Viçosa Brazil Electrical Engineering Department Universidade Federal de Vicosa Viçosa Brazil

Multi-robot systems can provide substantial increase in efficiency and/or flexibility in different scenarios. Applications in various settings have been studied in the literature, such as disaster management, surveillance, object transportation as well as search-and-rescue. A particular case that can highly benefit from the employment of multiple agents is the logistics in a warehouse scenario. This work proposes an multi-agent Q-learning based algorithm with curriculum learning and transfer learning to perform the path planning process. With progressively more complex stages of training as well as knowledge transfer from one stage to another, the algorithm is capable of achieve high success rates. In order to validate the proposed method, simulations were done to compare it to other combinations of the used techniques, as well as using Q-learning only. Scalability tests were also performed. The proposed method achieved up to 94% success rate after training.

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Ferroelectric domain nucleation and switching pathways in hafnium oxide.

arXiv

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arXiv 2023年

作者： Sebastian Calderon, V. Jaszewski, Samantha T. Kelley, Kyle P. Ihlefeld, Jon F. Dickey, Elizabeth Department of Materials Science and Engineering Carnegie Mellon University PittsburghPA15213 United States Department of Materials Science and Engineering University of Virginia CharlottesvilleVA22904 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Charles L. Brown Department of Electrical and Computer Engineering CharlottesvilleVA22904 United States

Nanoscale ferroelectrics that can be integrated into microelectronic fabrication processes are highly desirable for low-power computing and non-volatile memory devices. However, scalable novel ferroelectric materials, such as hafnium oxide (HfO2), remain in a state of development, and a clear understanding of the effects of relevant compositional and processing parameters to control their ferroelectric properties and the actual polarization switching mechanisms are still under investigation. One key fundamental knowledge gap is the polarization switching pathway in ferroelectric hafnia. To further our fundamental understanding of domain nucleation and switching, we have studied polarization switching pathways in HfO2-x thin films in real-time at the atomic scale using transmission electron microscopy. We employed differential phase contrast imaging that allows for the acquisition of both hafnium and oxygen atomic column signals and facilitates the observation of relative movement of atomic columns between both sublattices. Our results demonstrate that the switching pathway involves a transient tetragonal-like local structure, as oxygen ions shift in locations and remain within their parent hafnium polyhedra. © 2023, CC BY.

关键词： Hafnium oxides

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engineering Casimir interactions with epsilon-near-zero materials

arXiv

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arXiv 2021年

作者： Camacho, Miguel Gong, Tao Spreng, Benjamin Liberal, Iñigo Engheta, Nader Munday, Jeremy N. Department of Electrical and Systems Engineering University of Pennsylvania PhiladelphiaPA19104 United States Department of Electronics and Electromagnetism Universidad de Sevilla Seville41012 Spain Department of Electrical and Computer Engineering University of California DavisCA95616 United States Department of Materials Science and Engineering University of California DavisCA95616 United States Department of Electrical and Electronic Engineering Public University of Navarra Pamplona31006 Spain

In this paper we theoretically demonstrate the tunability of the Casimir force both in sign and magnitude between parallel plates coated with dispersive materials. We show that this force, existing between uncharged plates, can be tuned by carefully choosing the value of the plasma frequency (i.e., the epsilon-near-zero frequency) of the coating in the neighborhood of the resonance frequency of the cavity. The coating layer enables a continuous variation of the force between four limiting values when a coating is placed on each plate. We explore the consequences of such variation when pairs of electric and magnetic conductors (i.e. low and high impedance surfaces) are used as substrates on either side, showing that this continuous variation results in changes in the sign of the force, leading to both stable and unstable conditions, which could find interesting potential applications in nanomechanics including nanoparticle tweezing. Copyright © 2021, The Authors. All rights reserved.

关键词： Quantum theory

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