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Complex dielectric function of GaAs1−xBix as a function of Bi content

Physical Review materials 2019年第5期3卷 054601-054601页

作者： Mahsa Mahtab Ron Synowicki Vahid Bahrami-Yekta Lars C. Bannow Stephan W. Koch Ryan B. Lewis Thomas Tiedje Department of Electrical and Computer Engineering University of Victoria Victoria British Columbia Canada V8W 2Y2 J. A. Woollam Co. Inc. 645 M Street Suite 102 Lincoln Nebraska 68508 USA Department of Physics and Materials Science Center Philipps-Universität Marburg 35032 Marburg Germany Paul-Drude-Institut für Festkörperelektronik Hausvogteiplatz 5-7 Berlin 10117 Germany

The complex dielectric constants of GaAs1−xBix alloys grown by molecular beam epitaxy with x=0% to 17% have been measured over the spectral range from 0.37 to 9.1 eV using spectroscopic ellipsometry. Critical points in the joint density of states have been analyzed by fitting the line shape of the Van Hove singularities in the dielectric function derived from the ellipsometry data. The critical points generally match similar critical points in the dielectric function of GaAs with at least one alternative critical point. The energy of the critical points involving transitions from the top of the valence band show a strong dependence on Bi concentration similar to the composition dependence of the band gap, while the other critical points have a weaker dependence on Bi concentration. The measured composition dependence of the band gap and the energy of the split-off hole band are in good agreement with density functional calculations. The composition dependence of the index of refraction in the vicinity of the band gap for GaAs1−xBix alloys is an order of magnitude larger than the composition dependence of the index of refraction in Ga1−xInxAs alloys.

关键词： Dielectric properties Electro-optical spectra Electronic structure of atoms & molecules III-V semiconductors Semiconductor compounds Ellipsometry

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An efficient and accurate framework for calculating lattice thermal conductivity of solids:AFLOW-AAPL Automatic Anharmonic Phonon Library

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npj Computational materials 2017年第1期3卷 79-88页

作者： Jose J.Plata Pinku Nath Demet Usanmaz Jesus Carrete Cormac Toher Maarten de Jong Mark Asta Marco Fornari Marco Buongiorno Nardelli Stefano Curtarolo Department of Mechanical Engineering and Materials Science Duke UniversityDurhamNC 27708USA Institute of Materials Chemistry TU WienA-1060 ViennaAustria Department of Materials Science and Engineering University of CaliforniaBerkeley210 Hearst Memorial Mining BuildingBerkeleyUSA SpaceX 1 Rocket RoadHawthorneCA 90250USA Department of Physics and Science of Advanced Materials Program Central Michigan UniversityMount PleasantMI 48859USA Department of Physics and Department of Chemistry University of North TexasDentonTXUSA Materials Science Electrical EngineeringPhysics and ChemistryDuke UniversityDurhamNC 27708USA

One of the most accurate approaches for calculating lattice thermal conductivity,κ_(l),is solving the Boltzmann transport equation starting from third-order anharmonic force *** addition to the underlying approximations of ab-initio parameterization,two main challenges are associated with this path:high computational costs and lack of automation in the frameworks using this methodology,which affect the discovery rate of novel materials with ad-hoc ***,the Automatic Anharmonic Phonon Library(AAPL)is *** efficiently computes interatomic force constants by making effective use of crystal symmetry analysis,it solves the Boltzmann transport equation to obtain κ_(l),and allows a fully integrated operation with minimum user intervention,a rational addition to the current high-throughput accelerated materials development framework ***“experiment ***”study of the approach is shown,comparing accuracy and speed with respect to other available packages,and for materials characterized by strong electron localization and *** AAPL with the pseudo-hybrid functional ACBN0 is possible to improve accuracy without increasing computational requirements.

关键词： properties. harmonic calculating

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PAPR reduction using iterative clipping/filtering and ADMM approaches for OFDM-based mixed-numerology systems

arXiv

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arXiv 2019年

作者： Liu, Xiaoran Zhang, Xiaoying Zhang, Lei Xiao, Pei Wei, Jibo Zhang, Haijun Leung, Victor C.M. Department of Electronic Science National University of Defense Technology Changsha410073 China School of Engineering University of Glasgow GlasgowG12 8QQ United Kingdom 5G Innovation Centre Institute for Communication Systems University of Surrey GuildfordGU2 7XH United Kingdom Beijing Advanced Innovation Center for Materials Genome Engineering Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services University of Science and Technology Beijing Beijing100083 China Department of Electrical and Computer Engineering University of British Columbia VancouverBCV6T 1Z4 Canada

Mixed-numerology transmission is proposed to support a variety of communication scenarios with diverse requirements. However, as the orthogonal frequency division multiplexing (OFDM) remains as the basic waveform, the peak-to average power ratio (PAPR) problem is still cumbersome. In this paper, based on the iterative clipping and filtering (ICF) and optimization methods, we investigate the PAPR reduction in the mixed-numerology systems. We first illustrate that the direct extension of classical ICF brings about the accumulation of inter-numerology interference (INI) due to the repeated execution. By exploiting the clipping noise rather than the clipped signal, the noise-shaped ICF (NS-ICF) method is then proposed without increasing the INI. Next, we address the in-band distortion minimization problem subject to the PAPR constraint. By reformulation, the resulting model is separable in both the objective function and the constraints, and well suited for the alternating direction method of multipliers (ADMM) approach. The ADMM-based algorithms are then developed to split the original problem into several subproblems which can be easily solved with closed-form solutions. Furthermore, the applications of the proposed PAPR reduction methods combined with filtering and windowing techniques are also shown to be effective. Copyright © 2019, The Authors. All rights reserved.

关键词： Orthogonal frequency division multiplexing

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Stretchable Bioelectronics: A Versatile Sacrificial Layer for Transfer Printing of Wide Bandgap materials for Implantable and Stretchable Bioelectronics (Adv. Funct. Mater. 43/2020)

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Advanced Functional materials 2020年第43期30卷

作者： Tuan‐Anh Pham Tuan‐Khoa Nguyen Raja Kumar Vadivelu Toan Dinh Afzaal Qamar Sharda Yadav Yusuke Yamauchi John A. Rogers Nam‐Trung Nguyen Hoang‐Phuong Phan Queensland Micro and Nanotechnology Centre Griffith University Nathan QLD 4111 Australia Department of Chemical Systems Engineering The University of Tokyo Bunkyo‐ku Tokyo 113‐0033 Japan Department of Mechanical Engineering University of Southern Queensland Springfield QLD 4300 Australia Electrical Engineering Department University of Michigan Ann Arbor MI 48109 USA School of Chemical Engineering Australian Institute for Bioengineering and Nanotechnology The University of Queensland St Lucia Brisbane QLD 4072 Australia Department of Plant & Environmental New Resources Kyung Hee University Gyeonggi‐do Yongin 17104 South Korea Department of Materials Science and Engineering Department of Biomedical Engineering Department of Neurological Surgery Department of Chemistry Department of Mechanical Engineering Department of Electrical and Computer Science Center for Bio‐Integrated Electronics Simpson Querrey Institute for Nano/biotechnology Northwestern University Evanston IL 60208 USA

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Valley-selective optical Stark effect probed by Kerr rotation

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Physical Review B 2018年第4期97卷 045307-045307页

作者： Trevor LaMountain Hadallia Bergeron Itamar Balla Teodor K. Stanev Mark C. Hersam Nathaniel P. Stern Applied Physics Program Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA Department of Chemistry Northwestern University Evanston Illinois 60208 USA Department of Electrical Engineering and Computer Science Northwestern University Evanston Illinois 60208 USA

The ability to monitor and control distinct states is at the heart of emerging quantum technologies. The valley pseudospin in transition metal dichalcogenide (TMDC) monolayers is a promising degree of freedom for such control, with the optical Stark effect allowing for valley-selective manipulation of energy levels in WS2 and WSe2 using ultrafast optical pulses. Despite these advances, understanding of valley-sensitive optical Stark shifts in TMDCs has been limited by reflectance-based detection methods where the signal is small and prone to background effects. More sensitive polarization-based spectroscopy is required to better probe ultrafast Stark shifts for all-optical manipulation of valley energy levels. Here, we show time-resolved Kerr rotation to be a more sensitive probe of the valley-selective optical Stark effect in monolayer TMDCs. Compared to the established time-resolved reflectance methods, Kerr rotation is less sensitive to background effects. Kerr rotation provides a fivefold improvement in the signal-to-noise ratio of the Stark effect optical signal and a more precise estimate of the energy shift. This increased sensitivity allows for observation of an optical Stark shift in monolayer MoS2 that exhibits both valley and energy selectivity, demonstrating the promise of this method for investigating this effect in other layered materials and heterostructures.

关键词： Dielectric properties Excitons Semiconductors Transition metal dichalcogenides Kerr effect Reflectivity

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Switchable and unidirectional plasmonic beacons in hyperbolic two-dimensional materials

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Physical Review B 2019年第20期99卷 201405(R)-201405(R)页

作者： Andrei Nemilentsau Tobias Stauber Guillermo Gómez-Santos Mitchell Luskin Tony Low Department of Electrical & Computer Engineering University of Minnesota Minneapolis Minnesota 55455 USA Materials Science Factory Instituto de Ciencia de Materiales de Madrid CSIC E-28049 Madrid Spain Departamento de Física de la Materia Condensada Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC) Universidad Autónoma de Madrid E-28049 Madrid Spain School of Mathematics University of Minnesota Minneapolis Minnesota 55455 USA

In hyperbolic two-dimensional (2D) materials, energy is channeled into their deep subwavelength polaritonic modes via four narrow beams. Here, we consider the launching of surface polaritons in hyperbolic 2D materials and demonstrate that efficient unidirectional excitation is possible with an elliptically polarized electric dipole, with the optimal choice of dipole ellipticity depending on the materials' optical constants. The selection rules afforded by the choice of dipole polarization allow turning off up to two beams, and even three if the dipole is placed close to an edge. This makes the dipole a directionally switchable beacon for the launching of subdiffractional polaritonic beams, a potential logical gate. We develop an analytical approximation of the excitation process which describes well the results of the numerical simulations and affords a simple physical interpretation.

关键词： Nanoantennas Photonics Plasmonics Plasmons Hyperbolic metamaterials Metamaterials

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Remote Blind State Preparation with Weak Coherent Pulses in the Field

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Physical Review Letters 2019年第10期123卷 100503-100503页

作者： Yang-Fan Jiang Kejin Wei Liang Huang Ke Xu Qi-Chao Sun Yu-Zhe Zhang Weijun Zhang Hao Li Lixing You Zhen Wang Hoi-Kwong Lo Feihu Xu Qiang Zhang Jian-Wei Pan Shanghai Branch National Laboratory for Physical Sciences at Microscale and Department of Modern Physics University of Science and Technology of China Shanghai 201315 China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui 230026 China Centre for Quantum Information and Quantum Control Department of Electrical & Computer Engineering and Department of Physics University of Toronto Toronto Ontario M5S 3G4 Canada State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China

Quantum computing has seen tremendous progress in past years. Due to implementation complexity and cost, the future path of quantum computation is strongly believed to delegate computational tasks to powerful quantum servers on the cloud. Universal blind quantum computing (UBQC) provides the protocol for the secure delegation of arbitrary quantum computations, and it has received significant attention. However, a great challenge in UBQC is how to transmit a quantum state over a long distance securely and reliably. Here, we solve this challenge by proposing a resource-efficient remote blind qubit preparation (RBQP) protocol, with weak coherent pulses for the client to produce, using a compact and low-cost laser. We experimentally verify a key step of RBQP—quantum nondemolition measurement—in the field test over 100 km of fiber. Our experiment uses a quantum teleportation setup in the telecom wavelength and generates 1000 secure qubits with an average fidelity of (86.9±1.5)%, which exceeds the quantum no-cloning fidelity of equatorial qubit states. The results prove the feasibility of UBQC over long distances, and thus serves as a key milestone towards secure cloud quantum computing.

关键词： Optical quantum information processing Quantum computation Quantum cryptography Quantum optics Quantum protocols Quantum teleportation

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Nonlocal Spin Transport Mediated by a Vortex Liquid in Superconductors

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Physical Review Letters 2018年第18期121卷 187203-187203页

作者： Se Kwon Kim Roberto Myers Yaroslav Tserkovnyak Department of Physics and Astronomy University of California Los Angeles California 90095 USA Department of Physics and Astronomy University of Missouri Columbia Missouri 65211 USA Department of Materials Science and Engineering The Ohio State University Columbus Ohio 43210 USA Department of Electrical and Computer Engineering The Ohio State University Columbus Ohio 43210 USA

Departing from the conventional view on superconducting vortices as a parasitic source of dissipation for charge transport, we propose to use mobile vortices as topologically stable information carriers. To this end, we start by constructing a phenomenological theory for the interconversion between spin and vorticity, a topological charge carried by vortices, at the interface between a magnetic insulator and a superconductor, by invoking the interfacial spin Hall effect therein. We then show that a vortex liquid in superconductors can serve as a spin-transport channel between two magnetic insulators by encoding spin information in the vorticity. The vortex-mediated nonlocal signal between the two magnetic insulators is shown to decay algebraically as a function of their separation, contrasting with the exponential decay of the quasiparticle-mediated spin transport. We envision that hydrodynamics of topological excitations, such as vortices in superconductors and domain walls in magnets, may serve as a universal framework to discuss long-range transport properties of ordered materials.

关键词： Nucleation on surfaces Spin Hall effect Spintronics Superconductivity Topological defects Vortex flows Vortices in superconductors

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Quantum metamaterial for nondestructive microwave photon counting

arXiv

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arXiv 2020年

作者： Grimsmo, Arne Løhre Royer, Baptiste Kreikebaum, John Mark Ye, Yufeng O'Brien, Kevin Siddiqi, Irfan Blais, Alexandre Institut quantique Départment de Physique Université de Sherbrooke SherbrookeQCJ1K 2R1 Canada Centre for Engineered Quantum Systems School of Physics The University of Sydney SydneyNSW2006 Australia Department of Physics Yale University New HavenCT06520 United States Materials Science Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Quantum Nanoelectronics Laboratory Department of Physics University of California BerkeleyCA94720 United States Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Canadian Institute for Advanced Research Toronto Canada

Detecting traveling photons is an essential primitive for many quantum information processing tasks. We introduce a single-photon detector design operating in the microwave domain, based on a weakly nonlinear metamaterial where the nonlinearity is provided by a large number of Josephson junctions. The combination of weak nonlinearity and large spatial extent circumvents well-known obstacles limiting approaches based on a localized Kerr medium. Using numerical many-body simulations we show that the single-photon detection fidelity increases with the length of the metamaterial to approach one at experimentally realistic lengths. A remarkable feature of the detector is that the metamaterial approach allows for a large detection bandwidth. In stark contrast to conventional photon detectors operating in the optical domain, the photon is not destroyed by the detection and the photon wavepacket is minimally disturbed. The detector design we introduce offers new possibilities for quantum information processing, quantum optics and metrology in the microwave frequency domain. Copyright © 2020, The Authors. All rights reserved.

关键词： Photons

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Erratum: “Adsorption-controlled growth of Ga2O3 by suboxide molecular-beam epitaxy,” [APL. Mater. 9, 031101 (2021)]

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APL materials 2021年第4期9卷

作者： Patrick Vogt Felix V. E. Hensling Kathy Azizie Celesta S. Chang David Turner Jisung Park Jonathan P. McCandless Hanjong Paik Brandon J. Bocklund Georg Hoffmann Oliver Bierwagen Debdeep Jena Huili G. Xing Shin Mou David A. Muller Shun-Li Shang Zi-Kui Liu Darrell G. Schlom 1Department of Materials Science and Engineering Cornell University Ithaca New York 14853 USA 2School of Applied and Engineering Physics Cornell University Ithaca New York 14853 USA 3Air Force Research Laboratory Materials and Manufacturing Directorate Wright Patterson AFB Ohio 45433 USA 4Azimuth Corporation 2970 Presidential Drive Suite 200 Fairborn Ohio 45324 USA 5School of Electrical and Computer Engineering Cornell University Ithaca New York 14853 USA 6Platform for the Accelerated Realization Analysis and Discovery of Interface Materials (PARADIM) Cornell University Ithaca New York 14853 USA 7Department of Materials Science and Engineering Pennsylvania State University University Park Pennsylvania 16802 USA 8Paul-Drude-Institut für Festkörperelektronik Leibniz-Institut im Forschungsverbund Berlin e.V. Hausvogteiplatz 5-7 10117 Berlin Germany 9Kavli Institute at Cornell for Nanoscale Science Ithaca New York 14853 USA 10Leibniz-Institut für Kristallzüchtung Max-Born-Str. 2 12489 Berlin Germany

In the original article,1 the author Georg Hoffmann was misspelled as “Georg Hoffman.” The name appears correctly above.

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