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Pressure-induced large enhancement of Néel temperature and electric polarization in the hexagonal multiferroic Lu0.5Sc0.5FeO3

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Physical Review B 2019年第21期100卷 214408-214408页

作者： Fengliang Liu Changsong Xu Shoudong Shen Nana Li Hangwen Guo Xujie Lü Hongjun Xiang L. Bellaiche Jun Zhao Lifeng Yin Wenge Yang Wenbin Wang Jian Shen State Key Laboratory of Surface Physics and Department of Physics Fudan University Shanghai 200433 China Center for High Pressure Science and Technology Advanced Research (HPSTAR) Shanghai 201203 China Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai 200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093 China

Hexagonal ferrites (h−RFeO3) have attracted great attention for their high ferroelectric transition temperature, strong magnetoelectric couplings, and tunable Néel temperature (TN) and electric polarization. While introducing structural distortion has been previously found to be effective to raise TN and polarization in h−RFeO3, it is generally difficult to create sizable structural distortion by common approaches including substrate-induced epitaxial strain and chemical doping. Here, we use high-pressure x-ray-diffraction measurements to show that pressure can generate large structural distortion and R-layer displacement of h−RFeO3, resulting with dramatically enhancement of polarization and TN. Density-functional theory calculations reveal that the enlarged c/a ratio results in an ∼70 K increase of TN along with a significant enhancement of ferroelectric polarization. Our results suggest that pressure is effective to tune structural distortions and related multiferroicity of the h−RFeO3 system, making h−RFeO3 a promising material for spintronic applications.

关键词： Crystal structure Ferroelectricity First-principles calculations Magnetic phase transitions Pressure effects Multiferroics Density functional calculations X-ray diffraction

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Illinois Express quantum Network (IEQNET): Metropolitan-scale experimental quantum networking over deployed optical fiber

arXiv

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arXiv 2021年

作者： Chung, Joaquin Kanter, Gregory Lauk, Nikolai Valivarthi, Raju Wu, Wenji Ceballos, Russell R. Peña, Cristián Sinclair, Neil Thomas, Jordan Xie, Si Kettimuthu, Rajkumar Kumar, Prem Spentzouris, Panagiotis Spiropulu, Maria Data Science and Learning Division Argonne National Laboratory 9700 S Cass Ave. LemontIL60439 United States University of Chicago Consortium for Advanced Science and Engineering 924 E 57th St ChicagoIL60637 United States NuCrypt LLC 1840 Oak Ave EvanstonIL60201 United States Center for Photonic Communication and Computing Department of Electrical and Computer Engineering McCormick School of Engineering and Applied Science Northwestern University 2145 Sheridan Road EvanstonIL60208-3118 United States Division of Physics Mathematics and Astronomy California Institute of Technology 1200 E. California Blvd. PasadenaCA91125 United States California Institute of Technology 1200 E. California Blvd. PasadenaCA91125 United States Fermi National Accelerator Laboratory Kirk Rd and Pine St BataviaIL60510 United States Department of Chemistry Physics and Engineering Studies Chicago State University 9501 S. King Dr. ChicagoIL60628 United States Pittsburgh Quantum Institute B4 Thaw Hall 4061 O'Hara Street PittsburghPA15260 United States John A. Paulson School of Engineering and Applied Sciences Harvard University 29 Oxford St. CambridgeMA02138 United States 2205 Tech Drive Suite 1-160 EvanstonIL60208 United States Department of Physics and Astronomy Northwestern University 2145 Sheridan Road EvanstonIL60208-3112 United States

The Illinois Express quantum Network (IEQNET) is a program to realize metro-scale quantum networking over deployed optical fiber using currently available technology. IEQNET consists of multiple sites that are geographically dispersed in the Chicago metropolitan area. Each site has one or more quantum nodes (Q-nodes) representing the communication parties in a quantum network. Q-nodes generate or measure quantum signals such as entangled photons and communicate the results via standard, classical, means. The entangled photons in IEQNET nodes are generated at multiple wavelengths, and are selectively distributed to the desired users via optical switches. Here we describe the network architecture of IEQNET, including the Internet-inspired layered hierarchy that leverages software-defined-networking (SDN) technology to perform traditional wavelength routing and assignment between the Q-nodes. Specifically, SDN decouples the control and data planes, with the control plane being entirely classical. Issues associated with synchronization, calibration, network monitoring, and scheduling will be discussed. An important goal of IEQNET is demonstrating the extent to which the control plane can coexist with the data plane using the same fiber lines. This goal is furthered by the use of tunable narrow-band optical filtering at the receivers and, at least in some cases, a wide wavelength separation between the quantum and classical channels. We envision IEQNET to aid in developing robust and practical quantum networks by demonstrating metro-scale quantum communication tasks such as entanglement distribution and quantum-state teleportation. © 2021, CC BY.

关键词： Optical fibers

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Tape-time processing: Kinetics and mechanisms of native oxidation of transition metal dichalcogenides ZrSxSe2-x and MoS2

arXiv

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arXiv 2020年

作者： Jo, Seong Soon Singh, Akshay Yang, Liqiu Tiwari, Subodh C. Hong, Sungwook Krishnamoorthy, Aravind Sales, Maria Gabriela Oliver, Sean M. Fox, Joshua Cavalero, Randal L. Snyder, David W. Vora, Patrick M. McDonnell, Stephen J. Vashishta, Priya Kalia, Rajiv K. Nakano, Aiichiro Jaramillo, Rafael Department of Materials Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Collaboratory for Advanced Computing and Simulation University of Southern California Los AngelesCA90089 United States Department of Physics and Engineering California State University BakersfieldCA93311 United States Department of Materials Science and Engineering University of Virginia CharlottesvilleVA22904 United States Electronic Materials and Devices Department Applied Research Laboratory and 2-Dimensional Crystal Consortium Materials Research Institute Pennsylvania State University University ParkPA16802 United States Department of Physics and Astronomy George Mason University FairfaxVA22030 United States Quantum Materials Center George Mason University FairfaxVA22030 United States

A thorough understanding of the processing and properties of native oxides is essential for designing semiconductor devices. This is no less true for nanomaterials than it is for legacy semiconductors such as silicon, for which control and understanding of the native oxide was a seminal achievement of 20th century materials science. Layered transition metal dichalcogenides nominally have inert, fully-passivated surfaces, but it is well-known that this is an oversimplification and that many TMDs oxidize readily. Here we report on experiments and simulations that reveal the rate and mechanism of oxidation of MoS2 and ZrSxSe2-x alloys in laboratory conditions. We find that MoS2 surfaces are indeed stable, with no oxidation for up to a year exposure. In contrast, ZrSxSe2-x alloys oxidize spontaneously and the oxide growth is not self-limited. Oxidation proceeds by Zr-O bond switching that collapses the van der Waals gaps, and is facilitated by progressive redox transitions of the chalcogen. In contrast, the MoS2 surface remains inert due to energetically-unfavorable oxygen adsorption. Our results provide quantitative and conceptual guidance for designing and processing semiconductor devices based on MoS2 and ZrSxSe2-x, and identify the atomistic-scale mechanisms of bonding and phase transformations in layered materials with competing anions. Copyright © 2020, The Authors. All rights reserved.

关键词： Transition metals

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Quantifying the unextendibility of entanglementa

arXiv

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arXiv 2019年

作者： Wang, Kun Wang, Xin Wilde, Mark M. Institute for Quantum Computing Baidu Research Beijing100193 China Guangzhou China Hearne Institute for Theoretical Physics Department of Physics and Astronomy Center for Computation and Technology Louisiana State University Baton RougeLA70803 United States School of Electrical and Computer Engineering Cornell University IthacaNY14850 United States

Entanglement is a striking feature of quantum mechanics, and it has a key property called unextendibility. In this paper, we present a framework for quantifying and investigating the unextendibility of general bipartite quantum states. First, we define the unextendible entanglement, a family of entanglement measures based on the concept of a state-dependent set of free states. The intuition behind these measures is that the more entangled a bipartite state is, the less entangled each of its individual systems is with a third party. Second, we demonstrate that the unextendible entanglement is an entanglement monotone under two-extendible quantum operations, including local operations and one-way classical communication as a special case. Normalization and faithfulness are two other desirable properties of unextendible entanglement, which we establish here. We further show that the unextendible entanglement provides efficiently computable benchmarks for the rate of exact entanglement or secret key distillation, as well as the overhead of probabilistic entanglement or secret key distillation. Copyright © 2019, The Authors. All rights reserved.

关键词： Distillation

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Symmetry-protected ideal type-ii weyl phonons in cdte

arXiv

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arXiv 2019年

作者： Xia, B.W. Wang, R. Chen, Z.J. Zhao, Y.J. Xu, H. Department of Physics Shenzhen Key Laboratory of Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Department of Physics Hong Kong University of Science and Technology Clear Water Bay Hong Kong China Institute for Structure and Function & Department of physics Chongqing University Chongqing400044 China Department of Physics South China University of Technology Guangzhou510640 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen518055 China

Nontrivial low-energy excitations of crystalline solids have insightfully strengthened understanding of elementary particles in quantum field theory. Usually, topological quasiparticles are mainly focused on fermions in topological semimetals. In this work, we alternatively show by first-principles calculations and symmetry analysis that ideal type-II Weyl phonons are present in zinc-blende cadmium telluride (CdTe), a well-known II-VI semiconductor. Importantly, these type-II Weyl phonons originate from the inversion between the longitudinal acoustic and transverse optical branches. Symmetry guarantees the type-II Weyl points to lie along the high-symmetry lines at the boundaries of Brillouin zone even with breaking the inversion symmetry, exhibiting the robustness of protected phonon features. The nontrivial phonon surface states and surface arcs projected on the semi-finite (001) and (111) surfaces are investigated. The phonon surface arcs connecting the Weyl points with opposite chirality, guaranteed to be very long, are clearly visible. This work not only offers a promising candidate for studying type-II Weyl phonons, but also provides a route to realize symmetry-protected nontrivial phonons and related applications in realistic materials. Copyright © 2019, The Authors. All rights reserved.

关键词： Phonons

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U(1) CS Theory vs SL(2) CS Formulation: Boundary Theory and Wilson Line

arXiv

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arXiv 2020年

作者： Huang, Xing Ma, Chen-Te Shu, Hongfei Wu, Chih-Hung Institute of Modern Physics Northwest University Xi'An710069 China Shaanxi Key Laboratory for Theoretical Physics Frontiers Xi'An710069 China NSFC-SPTP Peng Huanwu Center for Fundamental Theory Xi'An710127 China Asia Pacific Center for Theoretical Physics Pohang University of Science and Technology Gyeongsangbuk-do Pohang37673 Korea Republic of Guangdong Provincial Key Laboratory of Nuclear Science Institute of Quantum Matter South China Normal University Guangdong Guangzhou510006 China School of Physics and Telecommunication Engineering South China Normal University Guangdong Guangzhou510006 China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Southern Nuclear Science Computing Center South China Normal University Guangzhou510006 China The Laboratory for Quantum Gravity and Strings Department of Mathematics and Applied Mathematics University of Cape Town Private Bag Rondebosch7700 South Africa Beijing101408 China Tsinghua University Beijing100084 China Nordita KTH Royal Institute of Technology Stockholm University Roslagstullsbacken 23 StockholmSE-106 91 Sweden Department of Physics Tokyo Institute of Technology Tokyo152-8551 Japan Department of Physics University of California Santa BarbaraCA93106 United States

We first derive the boundary theory from the U(1) Chern-Simons theory. The boundary action on an n-sheet manifold appears from its back-reaction of the Wilson line. The reason is that the U(1) Chern-Simons theory can provide an exact effective action when introducing the Wilson line. The Wilson line in the pure AdS3 Einstein gravity is equivalent to entanglement entropy in the boundary theory up to classical gravity. The U(1) Chern-Simons theory deviates by a self-interaction term from the gauge formulation on the boundary. We also compare the Hayward term in the SL(2) Chern-Simons formulation to the Wilson line approach. Introducing two wedges can reproduce the entanglement entropy for a single interval at the classical level. We propose quantum generalization by combining the bulk and Hayward terms. The quantum correction of the partition function vanishes. In the end, we calculate the entanglement entropy for a single interval. The pure AdS3 Einstein gravity theory shows a shift of central charge by 26 at the one-loop level. The U(1) Chern-Simons theory does not show a shift from the quantum effect. The result is the same in the weak gravitational constant limit. The non-vanishing quantum correction shows that the Hayward term is incorrect. Copyright © 2020, The Authors. All rights reserved.

关键词： Entropy

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quantum engineering with hybrid magnonics systems and materials

arXiv

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arXiv 2021年

作者： Awschalom, D.D. Du, C.H.R. He, R. Heremans, F.J. Hoffmann, A. Hou, J.T. Kurebayashi, H. Li, Y. Liu, L. Novosad, V. Sklenar, J. Sullivan, S.E. Sun, D. Tang, H. Tiberkevich, V. Trevillian, C. Tsen, A.W. Weiss, L.R. Zhang, W. Zhang, X. Zhao, L. Zollitsch, C.W. Pritzker School of Molecular Engineering University of Chicago ChicagoIL United States Materials Science Division Center for Molecular Engineering Argonne National Laboratory LemontIL United States Department of Physics University of California San Diego San DiegoCA92093 United States Department of Electrical and Computer Engineering Texas Tech University LubbockTX79409 United States Materials Research Laboratory Department of Materials Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA United States London Centre for Nanotechnology University College London 17-19 Gordon Street LondonWCH1 0AH United Kingdom Materials Science Division Argonne National Laboratory LemontIL United States Department of Physics and Astronomy Wayne State University DetroitMI48201 United States Department of Physics North Carolina State University RaleighNC27695 United States Department of Electrical Engineering Yale University New HavenCT United States Department of Physics Oakland University MI48309 United States Institute for Quantum Computing Department of Chemistry University of Waterloo WaterlooON Canada Center for Nanoscale Materials Argonne National Laboratory LemontIL United States Department of Physics University of Michigan Ann ArborMI48109 United States

quantum technology has made tremendous strides over the past two decades with remarkable advances in materials engineering, circuit design and dynamic operation. In particular, the integration of different quantum modules has benefited from hybrid quantum systems, which provide an important pathway for harnessing the different natural advantages of complementary quantum systems and for engineering new functionalities. This review focuses on the current frontiers with respect to utilizing magnetic excitatons or magnons for novel quantum functionality. Magnons are the fundamental excitations of magnetically ordered solid-state materials and provide great tunability and flexibility for interacting with various quantum modules for integration in diverse quantum systems. The concomitant rich variety of physics and material selections enable exploration of novel quantum phenomena in materials science and engineering. In addition, the relative ease of generating strong coupling and forming hybrid dynamic systems with other excitations makes hybrid magnonics a unique platform for quantum engineering. We start our discussion with circuit-based hybrid magnonic systems, which are coupled with microwave photons and acoustic phonons. Subsequently, we are focusing on the recent progress of magnon-magnon coupling within confined magnetic systems. Next we highlight new opportunities for understanding the interactions between magnons and nitrogen-vacancy centers for quantum sensing and implementing quantum interconnects. Lastly, we focus on the spin excitations and magnon spectra of novel quantum materials investigated with advanced optical characterization. Copyright © 2021, The Authors. All rights reserved.

关键词： quantum optics

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Tunable quantum switch realized with a single Λ-level atom coupled to the microtoroidal cavity

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Physical Review A 2019年第5期100卷 053851-053851页

作者： Davit Aghamalyan Jia-Bin You Hong-Son Chu Ching Eng Png Leonid Krivitsky Leong Chuan Kwek Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 Singapore 117543 Institute of High Performance Computing A*STAR (Agency for Science Technology and Research) 1 Fusionopolis Way #16-16 Connexis Singapore 138632 Institute of Materials Research and Engineering A*STAR (Agency for Science Technology and Research) 2 Fusionopolis Way #08-03 Innovis Singapore 138634 MajuLab CNRS-UNS-NUS-NTU International Joint Research Unit UMI 3654 Singapore National Institute of Education and Institute of Advanced Studies Nanyang Technological University 1 Nanyang Walk Singapore 637616

We propose a realization of the quantum switch for coherent light fields for the fiber-coupled microdisk cavities. We demonstrate by combining numerical and analytical methods that both in strong coupling and bad cavity limits it is possible to change a system's behavior from being fully transparent to being fully reflective by varying the amplitude of the external control field. We remark that tuning the amplitude of the control field instead of cavity-atom coupling strength, which was suggested by S. Parkins et al., [Phys. Rev. A 90, 053822 (2014)] for two-level atoms and works only in the strong coupling limit, brings more control and tunability over the transmitted and reflected intensities. We also demonstrate the possibility of controlling the statistics of the input coherent field with the control field which opens the venue for obtaining quantum states of light.

关键词： Cavity quantum electrodynamics Optical microcavities quantum cavities Jaynes-Cummings model

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Design for Elliptical Micropillar Triplets for a Highly Efficient quantum-Dot Entangle Photon Pair Source

Design for Elliptical Micropillar Triplets for a Highly Effi...

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Asia Communications and Photonics Conference and Exhibition (ACP)

作者： Zhenhua Li Siwu Li Haolin Lu Shunfa Liu Jiawei Yang Ying Yu Siyuan Yu State Key Laboratory of Optoelectronic Materials and Technologies School of Electronics and Information Technology Sun Yat-sen University Guangzhou China State Key Laboratory of High Performance Computing Institute for Quantum Information College of Computer National University of Defense Technology Changsha China Photonics Group Merchant Venturers School of Engineering University of Bristol Bristol UK

A design of quantum-dot-based polarized entangle photon pair source by implementing three overlapping elliptical micropillars, leading to >80% collection efficiency and high Purcell factor for both exciton and biex... 详细信息

ISBN: (纸本)9781943580705

关键词： Electric fields Finite difference time domain Photonic entanglement Purcell effect quantum communications Spontaneous emission

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Supercurrent interference in semiconductor nanowire Josephson junctions

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Physical Review B 2019年第15期100卷 155431-155431页

作者： Praveen Sriram Sandesh S. Kalantre Kaveh Gharavi Jonathan Baugh Bhaskaran Muralidharan Department of Electrical Engineering Indian Institute of Technology Bombay Powai Mumbai 400076 India Department of Physics Indian Institute of Technology Bombay Powai Mumbai 400076 India Institute for Quantum Computing University of Waterloo Waterloo Ontario Canada N2L 3G1 Department of Physics and Astronomy University of Waterloo Waterloo Ontario Canada N2L 3G1 Department of Chemistry University of Waterloo Waterloo Ontario Canada N2L 3G1

Semiconductor-superconductor hybrid systems provide a promising platform for hosting unpaired Majorana fermions towards the realization of fault-tolerant topological quantum computing. In this study we employ the Keldysh nonequilibrium Green's function formalism to model quantum transport in normal-superconductor junctions. We analyze III-V semiconductor nanowire Josephson junctions (InAs/Nb) using a three-dimensional discrete lattice model described by the Bogoliubov–de Gennes Hamiltonian in the tight-binding approximation, and compute the Andreev bound state spectrum and current-phase relations. Recent experiments [Zuo et al., Phys. Rev. Lett. 119, 187704 (2017) and Gharavi et al., arXiv:1405.7455] reveal critical current oscillations in these devices, and our simulations confirm these to be an interference effect of the transverse subbands in the nanowire. We add disorder to model coherent scattering and study its effect on the critical current oscillations, with an aim to gain a thorough understanding of the experiments. The oscillations in the disordered junction are highly sensitive to the particular realization of the random disorder potential, and to the gate voltage. A macroscopic current measurement thus gives us information about the microscopic profile of the junction. Finally, we study dephasing in the channel by including elastic phase-breaking interactions. The oscillations thus obtained are in good qualitative agreement with the experimental data, and this signifies the essential role of phase-breaking processes in III-V semiconductor nanowire Josephson junctions.

关键词： Hybrid quantum systems Topological superconductors Nanowires Nonequilibrium Green's function

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