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Building a Casimir Metrology Platform with a Commercial MEMS Accelerometer

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arXiv 2018年

作者： Stange, Alexander Imboden, Matthias Javor, Josh Barrett, Lawrence K. Bishop, David J. Division of Material Science and Engineering Boston University BostonMA02215 United States Department of Mechanical Engineering Boston University BostonMA02215 United States Department of Physics Boston University BostonMA02215 United States Department of Electrical and Computer Engineering Boston University BostonMA02215 United States Department of Biomedical Engineering Boston University BostonMA02215 United States Institute of Microengineering École Polytechnique Fédérale de Lausanne Neuchâtel2000 Switzerland

The Casimir Effect is a physical manifestation of quantum fluctuations of the electromagnetic vacuum. When two metal plates are placed closely together, typically much less than a micron, the long wavelength modes between them are frozen out, giving rise to a net attractive force between the plates, scaling as d-4 (or d-3 for a spherical-planar geometry) even when they are not electrically charged. In this paper we observe the Casimir Effect in ambient conditions using a modified capacitive MEMS accelerometer. Using a feedback assisted pick-and-place assembly process we are able to attach various micro-structures onto the post-release MEMS, converting it from an inertial force sensor to a direct force measurement platform with pN resolution. With this system we are able to directly measure the Casimir force between a silver-coated microsphere and gold-coated silicon plate. This device is a step towards leveraging the Casimir Effect for cheap, sensitive, room temperature quantum metrology. Copyright © 2018, The Authors. All rights reserved.

关键词： Quantum theory

Physics-Based Image Reconstruction of SiC Grain Boundaries

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Microscopy and Microanalysis 2017年第S1期23卷 188-189页

作者： Ziabari, Amirkoushyar Bouman, Charles A Rickman, Jeffrey M Simmons, Jeff P Electrical and Computer Engineering (ECE) Purdue University West Lafayette IN USA Department of Material Science and Engineering Lehigh University Bethlehem PA USA Air Force Research Laboratory Wright-Patterson AFB OH USA

Compact localized states of open scattering media

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arXiv 2018年

作者： Sgrignuoli, Fabrizio Röntgen, Malte Morfonios, Christian V. Schmelcher, Peter Dal Negro, Luca Department of Electrical and Computer Engineering Boston University BostonMA02215 United States Zentrum fur optische Quantentechnologien Universität Hamburg Luruper Chaussee 149 Hamburg22761 Germany Hamburg Centre for Ultrafast Imaging Universitat Hamburg Luruper Chaussee 149 Hamburg22761 Germany Division of Material Science and Engineering Boston University BostonMA02215 United States Department of Physics Boston University BostonMA02215 United States

We study the compact localized scattering resonances of periodic and aperiodic chains of dipolar nanoparticles by combining the powerful Equitable Partition Theorem (EPT) of graph theory with the spectral dyadic Green's matrix formalism for the engineering of embedded quasi-modes in non-Hermitian open scattering systems in three spatial dimensions. We provide analytical and numerical design of the spectral properties of compact localized states in electromagnetically coupled chains and establish a connection with the distinctive behavior of Bound States in the Continuum. Our results extend the concept of compact localization to the scattering resonances of open systems with arbitrary aperiodic order beyond tight-binding models, and are relevant for the efficient design of novel photonic and plasmonic metamaterial architectures for enhanced light-matter interaction. Copyright © 2018, The Authors. All rights reserved.

关键词： Graph theory

Real-space-transfer mechanism of negative differential conductivity in gated graphene-phosphorene hybrid structures: Phenomenological heating model

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arXiv 2018年

作者： Ryzhii, V. Ryzhii, M. Svintsov, D. Leiman, V. Maltsev, P.P. Ponomarev, D.S. Mitin, V. Shur, M.S. Otsuji, T. Research Institute of Electrical Communication Tohoku University Sendai980-8577 Japan Institute of Ultra High Frequency Semiconductor Electronics of RAS Moscow117105 Russia Center for Photonics and Infrared Engineering Bauman Moscow State Technical University Moscow111005 Russia Department of Computer Science and Engineering University of Aizu Aizu-Wakamatsu965-8580 Japan Laboratory of 2D Material's Optoelectronics Moscow Institute of Physics and Technology Dolgoprudny141700 Russia Department of Electrical Engineering University at Buffalo SUNY BuffaloNY1460-1920 United States Departments of Electrical Electronics and Systems Engineering and Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute TroyNY12180 United States Electronics of the Future Inc. ViennaVA22181 United States

We analyze the nonlinear carrier transport in the gated graphene-phosphorene (G-P) hybrid structures - the G-P field-effect transistors (G-P-FETs) using a phenomenological model. This model assumes that due to high carrier densities in the G-P-channel, the carrier system, including the electrons and holes in both the G- and P-layers, is characterized by a single effective temperature. We demonstrate that a strong electric-field dependence of the G-P-channel conductivity and substantially non-linear current-voltage characteristics, exhibiting a negative differential conductivity, are associated with the carrier heating and the real-space carrier transfer between the G- and P-layers. The predicted features of the G-P-systems can be used in the detectors and sources of electromagnetic radiation and in the logical circuits. Copyright © 2018, The Authors. All rights reserved.

关键词： Graphene

Intrinsic 1T̕ phase induced in atomically thin 2H-MoTe2 by a single terahertz pulse

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arXiv 2019年

作者： Shi, Jiaojian Bie, Ya-Qing Zong, Alfred Fang, Shiang Chen, Wei Han, Jinchi Cao, Zhaolong Zhang, Yong Taniguchi, Takashi Watanabe, Kenji Bulović, Vladimir Kaxiras, Efthimios Baldini, Edoardo Jarillo-Herrero, Pablo Nelson, Keith A. Department of Chemistry Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States State Key Lab of Optoelectronic Materials and Technologies Guangdong Province Key Laboratory of Display Material and Technology School of Electronics and Information Technology Sun Yat-sen University Guangzhou510275 China Department of Chemistry University of California BerkeleyCA94720 United States Department of Physics Harvard University CambridgeMA02138 United States Department of Physics and Astronomy Center for Materials Theory Rutgers University PiscatawayNJ08854 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Center for Materials Science & Engineering Massachusetts Institute of Technology CambridgeMA02139 United States International Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Functional Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Department of Physics Center for Complex Quantum System The University of Texas at Austin AustinTX78712 United States

Polymorphic transitions in layered transition metal dichalcogenides provide an excellent platform for discovering exotic phenomena associated with metastable states, ranging from topological phase transitions1 to enhanced superconductivity2. In particular, the transition from 2H to 1T0-MoTe2, which was thought to be induced by high-energy photon irradiation3–5 among many other means6–9, has been intensely studied for its technological relevance in nanoscale transistors3. Despite the remarkable electrical performance arising from this 2H-to-1T0 transition, it remains controversial whether a crystalline 1T0 phase is produced because optical signatures of this putative transition are found to be associated with the formation of elemental Te clusters instead10,11. Here, we demonstrate the creation of an intrinsic 1T0 lattice after irradiating a mono- or few-layer 2H-MoTe2 with a single field-enhanced terahertz pulse, whose low photon energy limits possible structural damage by optical pulses. To visualize the temporal evolution of this irreversible transition, we further develop a single-shot terahertz pump-second harmonic probe technique, and we find that the transition out of the 2H phase occurs within 10 ns after photoexcitation. Our results not only resolve the long-standing debate over the light-induced polymorphic transition in MoTe2, they also highlight the unique capability of strong-field terahertz pulses in manipulating the structure of quantum materials. Copyright © 2019, The Authors. All rights reserved.

关键词： Transition metals

Room-temperature nanoseconds spin relaxation in WTe2and MoTe2thin films

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arXiv 2018年

作者： Wang, Qisheng Li, Jie Besbas, Jean Hsu, Chuang-Han Cai, Kaiming Yang, Li Cheng, Shuai Wu, Yang Zhang, Wenfeng Wang, Kaiyou Chang, Tay-Rong Lin, Hsin Chang, Haixin Yang, Hyunsoo Department of Electrical and Computer Engineering NUSNNI National University of Singapore Singapore117576 Singapore Center for Joining and Electronic Packaging State Key Laboratory of Material Processing and Die And Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan430074 China Centre for Advanced 2D Materials National University of Singapore 6 Science Drive 2 117546 Singapore SKLSM Institute of Semiconductors Chinese Academy of Sciences P. O. Box 912 Beijing100083 China Department of Physics National Tsing Hua University Hsinchu30013 Taiwan

The Weyl semimetal WTe2and MoTe2show great potential in generating large spin currents since they possess topologically-protected spin-polarized states and can carry a very large current density. In addition, the intrinsic noncentrosymmetry of WTe2and MoTe2endows with a unique property of crystal symmetry-controlled spin-orbit torques. An important question to be answered for developing spintronic devices is how spins relax in WTe2and MoTe2. Here, we report a room-temperature spin relaxation time of 1.2 ns (0.4 ns) in WTe2(MoTe2) thin film using the time-resolved Kerr rotation (TRKR). Based on ab initio calculation, we identify a mechanism of long-lived spin polarization resulting from a large spin splitting around the bottom of the conduction band, low electron-hole recombination rate and suppression of backscattering required by timereversal and lattice symmetry operation. In addition, we find the spin polarization is firmly pinned along the strong internal out-of-plane magnetic field induced by large spin splitting. Our work provides an insight into the physical origin of long-lived spin polarization in Weyl semimetals which could be useful to manipulate spins for a long time at room temperature. Copyright © 2018, The Authors. All rights reserved.

关键词： Spin polarization

Moiré excitons in Van der Waals heterostructures

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arXiv 2018年

作者： Tran, Kha Moody, Galan Wu, Fengcheng Lu, Xiaobo Choi, Junho Singh, Akshay Embley, Jacob Zepeda, André Campbell, Marshall Kim, Kyounghwan Rai, Amritesh Autry, Travis Sanchez, Daniel A. Taniguchi, Takashi Watanabe, Kenji Lu, Nanshu Banerjee, Sanjay K. Tutuc, Emanuel Yang, Li MacDonald, Allan H. Silverman, Kevin L. Li, Xiaoqin Department of Physics Center for Complex Quantum Systems University of Texas at Austin AustinTX78712 United States National Institute of Standards & Technology BoulderCO80305 United States Materials Science Division Argonne National Laboratory ArgonneIL60439 United States Department of Physics Washington University in St. Louis St. LouisMI63136 United States Microelectronics Research Center Department of Electrical and Computer Engineering University of Texas at Austin AustinTX78758 United States Department of Aerospace Engineering and Engineering Mechanics University of Texas at Austin AustinTX78712 United States National Institute of Material Science 1-1 Namiki Tsukuba Ibaraki205-0044 Japan Texas Materials Institute University of Texas at Austin AustinTX78712 United States Department of Material Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States

In van der Waals (vdW) heterostructures formed by stacking two monolayer semiconductors, lattice mismatch or rotational misalignment introduces an in-plane moiré superlattice. While it is widely recognized that a moiré superlattice can modulate the electronic band structure and lead to novel transport properties including unconventional superconductivity and insulating behavior driven by correlations, its influence on optical properties has not been investigated experimentally. We present spectroscopic evidence that interlayer excitons are confined by the moiré potential in a high-quality MoSe2/WSe2heterobilayer with small rotational twist. A series of interlayer exciton resonances with either positive or negative circularly polarized emission is observed in photoluminescence, consistent with multiple exciton states confined within the moiré potential. The recombination dynamics and temperature dependence of these interlayer exciton resonances are consistent with this interpretation. These results demonstrate the feasibility of engineering artificial excitonic crystals using vdW heterostructures for nanophotonics and quantum information applications. Copyright © 2018, The Authors. All rights reserved.

关键词： Van der Waals forces

Local symmetry theory of resonator structures for the real-space control of edge states in binary aperiodic chains

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arXiv 2018年

作者： Röntgen, M. Morfonios, C.V. Wang, R. Dal Negro, L. Schmelcher, P. Zentrum für Optische Quantentechnologien Universität Hamburg Luruper Chaussee 149 Hamburg22761 Germany Department of Electrical and Computer Engineering and Photonics Center Boston University BostonMA02215 United States Department of Physics Boston University BostonMA02215 United States Department of Material Science and Engineering Boston University BostonMA02215 United States Hamburg Centre for Ultrafast Imaging Universität Hamburg Luruper Chaussee 149 Hamburg22761 Germany

We propose a real-space approach explaining and controlling the occurrence of edge-localized gap states between the spectral quasibands of binary tight binding chains with deterministic aperiodic long-range order. The framework is applied to the Fibonacci, Thue-Morse and Rudin-Shapiro chains, representing different structural classes. Our approach is based on an analysis of the eigenstates at weak inter-site coupling, where they are shown to generically localize on locally reflection-symmetric substructures which we call local resonators. A perturbation theoretical treatment demonstrates the local symmetries of the eigenstates. Depending on the degree of spatial complexity of the chain, the proposed local resonator picture can be used to predict the occurrence of gap-edge states even for stronger couplings. Moreover, we connect the localization behavior of a given eigenstate to its energy, thus providing a quantitative connection between the real-space structure of the chain and its eigenvalue spectrum. This allows for a deeper understanding, based on local symmetries, of how the energy spectra of binary chains are formed. The insights gained allow for a systematic analysis of aperiodic binary chains and offers a pathway to control structurally induced edge states. Copyright © 2018, The Authors. All rights reserved.

关键词： Resonators

A Critical Analysis on the Thin Crystalline Silicon PV Module of the Lightweight PV System

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A Critical Analysis on the Thin Crystalline Silicon PV Modul...

2017 IEEE 44th Photovoltaic Specialist Conference (PVSC)

作者： Meixi Chen Abhishek Iyer Cheng-Hao Shih Lado Kurdgelashvili Robert Opila Department of Material Science and Engineering University of Delaware Newark Delaware USA Department of Electrical and Computer Engineering University of Delaware Newark Delaware USA Department of Energy and Environmental Policy University of Delaware Newark Delaware USA

This work provides an analysis of the thin crystalline silicon PV module for a Lightweight PV (LPV) system. We first examine the advantages of the LPV system and then discuss the technical and economic challenges of the thin crystalline silicon PV module in assisting LPV system development for future market penetration. A critical analysis is conducted on the efficiency and yield challenge, and the system weight and costs reduction of thin crystalline silicon PV for the future development of the LPV system. It has shown that the key in speeding up thin silicon LPV market diffusion lies in developing cost-effective passivation and light trapping methods, as well as high-yield thin silicon fabrication technologies.

关键词： Silicon Passivation Fabrication Light trapping Photovoltaic systems