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arXiv 2020年

作者： Zhang, Pengfei Huang, Zichang Song, Chao Guo, Qiujiang Song, Zixuan Dong, Hang Wang, Zhen Li, Hekang Han, Muxin Wang, Haohua Wan, Yidun Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation Zhejiang Province Key Laboratory of Quantum Technology and Device Department of Physics Zhejiang University Hangzhou310027 China State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Department of Physics Center for Field Theory and Particle Physics Institute for Nanoelectronic devices and Quantum computing Fudan University Shanghai200433 China Department of Physics Florida Atlantic University 777 Glades Road Boca RatonFL33431 United States Institut für Quantengravitation Universität Erlangen-Nürnberg Staudtstr. 7/B2 Erlangen91058 Germany Department of Physics and Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China

quantum computers are an increasingly hopeful means for understanding large quantum many-body systems bearing high computational complexity. Such systems exhibit complex evolutions of quantum states, and are prevailing in fundamental physics, e.g., quantum gravity. computing the transition amplitudes between different quantum states by quantum computers is one of the promising ways to solve such computational complexity problems. In this work, we apply a 10-qubit superconducting quantum processor, where the all-to-all circuit connectivity enables a many-body entangling gate that is highly efficient for state generation, to studying the transition amplitudes in loop quantum gravity. With the device metrics such as qubit coherence, control accuracy, and integration level being continuously improved, superconducting quantum processors are expected to outperform their classical counterparts in handling many-body dynamics and may lead to a deeper understanding of quantum gravity. Copyright © 2020, The Authors. All rights reserved.

关键词： Qubits

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Simulating gauge theories with variational quantum eigensolvers in superconducting microwave cavities

arXiv

引用

arXiv 2021年

作者： Zhang, Jinglei Ferguson, Ryan Kühn, Stefan Haase, Jan F. Wilson, C.M. Jansen, Karl Muschik, Christine A. Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Computation-based Science and Technology Research Center The Cyprus Institute 20 Kavafi Street Nicosia2121 Cyprus Institute of Theoretical Physics and IQST Universität Ulm Albert-Einstein-Allee 11 UlmD-89069 Germany Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada NIC DESY Zeuthen Platanenallee 6 Zeuthen15738 Germany Perimeter Institute for Theoretical Physics WaterlooONN2L 2Y5 Canada

quantum-enhanced computing methods are promising candidates to solve currently intractable problems. We consider here a variational quantum eigensolver (VQE), that delegates costly state preparations and measurements to quantum hardware, while classical optimization techniques guide the quantum hardware to create a desired target state. In this work, we propose a bosonic VQE using superconducting microwave cavities, overcoming the typical restriction of a small Hilbert space when the VQE is qubit based. The considered platform allows for strong nonlinearities between photon modes, which are highly customisable and can be tuned in situ, i.e. during running experiments. Our proposal hence allows for the realization of a wide range of bosonic ansatz states, and is therefore especially useful when simulating models involving degrees of freedom that cannot be simply mapped to qubits, such as gauge theories, that include components which require infinite-dimensional Hilbert spaces. We thus propose to experimentally apply this bosonic VQE to the U(1) Higgs model including a topological term, which in general introduces a sign problem in the model, making it intractable with conventional Monte Carlo methods. © 2021, CC BY-NC-SA.

关键词： Hilbert spaces

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Label-free phase change detection of lipid bilayers using nanoscale diamond magnetometry

arXiv

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arXiv 2020年

作者： Ishiwata, Hitoshi Watanabe, Hiroshi C. Hanashima, Shinya Iwasaki, Takayuki Hatano, Mutsuko PRESTO Japan Science and Technology Agency 7 Gobancho ChiyodaTokyo152-0076 Japan School of Engineering Department of Electrical and Electronic Engineering Tokyo Institute of Technology 2-12-1 Ookayama MeguroTokyo152-8552 Japan Quantum Computing Center Keio University 3-14-1 Hiyoshi Kohoku-kuYokohama223-8522 Japan Department of Chemistry Graduate School of Science Osaka University 1-1 Machikaneyama ToyonakaOsaka560-0043 Japan

The NV center in a diamond is a quantum sensor with exceptional quality for highly sensitive nanoscale analysis of NMR spectra and thermometry. In this study, we investigate nanoscale phase change detection of lipid bilayers utilizing ensemble-averaged nuclear spin detection from small volume ~ (6 nm)3, which was determined by the depth of the NV center. Analysis of nanoscale NMR signal confirm thickness of lipid bilayer to be 6.2 nm ± 3.4 nm with proton density of 65 proton/nm3 verifying formation of lipid bilayer on top of diamond sample. Correlation spectroscopy from nanoscale volume reveals quantum oscillation at 3.06 MHz corresponding to the Larmor frequency of proton at an applied magnetic field of 71.8 mT. The result of the correlation spectroscopy was compared with the 2D molecular diffusion model constructed by Monte Carlo simulation combined with results from molecular dynamics simulation. There is a change in diffusion constant from 1.5 nm2/μs to 3.5 nm2/μs when the temperature changes from 26.5 ℃ to 36.0 ℃. Our results demonstrate that simultaneous observation of changes in translational diffusion and temperature is possible in label-free measurements using nanoscale diamond magnetometry. Our method paves the way for label-free imaging of cell membranes for understanding its phase composition and dynamics. Copyright © 2020, The Authors. All rights reserved.

关键词： Nuclear magnetic resonance

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Symmetry-Protected Unpaired Weyl Phonons with Giant Arcs Spanning Full Surface Brillouin Zone

arXiv

引用

arXiv 2019年

作者： Wang, R. Xia, B.W. Chen, Z.J. Zheng, B.B. Zhao, Y.J. Xu, H. Department of Physics & Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 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

Weyl points are often believed to appear in pairs with opposite chirality. In this work, we propose that the number of right-handed Weyl points is not equal to that of left-handed Weyl points in topological phonon systems. Using first-principles calculations and symmetry analysis, we show that single Weyl phonons with linear dispersion and double Weyl phonons with quadratic dispersion coexist in realistic materials with trigonal or hexagonal lattices. These phonon Weyl points are guaranteed to locate at high-symmetry points due to the screw rotational symmetry, forming a unique triangular Weyl complex. In sharp contrast to conventional Weyl systems with surface arcs terminated at the projections of a pair of collinear Weyl points with opposite chirality, the phonon surface arcs of the unconventional triangular Weyl complex connect the projections of one double Weyl point and two single Weyl points. Importantly, the phonon surface arcs originating from the triangular Weyl complex are extremely long and span the entire surface Brillouin-zone. Furthermore, there are only nontrivial phonon surface states across the iso-frequency surface, which facilitates their detection in experiments and further applications. This work paves an avenue to explore unpaired Weyl quasiparticles and their nontrivial properties. Copyright © 2019, The Authors. All rights reserved.

关键词： Phonons

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Exotic Cooper pairing in multiorbital models of Sr2RuO4

引用

Physical Review B 2019年第13期100卷 134506-134506页

作者： Wen Huang Yi Zhou Hong Yao Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen 518055 China Institute for Advanced Study Tsinghua University Beijing 100084 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen 518005 China Beijing National Laboratory for Condensed Matter Physics & Institute of Physics Chinese Academy of Sciences Beijing 100190 China Kavli Institute for Theoretical Sciences & CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Low Dimensional Quantum Physics Tsinghua University Beijing 100084 China

The unconventional superconductivity in Sr2RuO4 continues to defy a unified interpretation. In this paper, we focus on some novel aspects of its superconducting pairing by exploiting the orbital degree of freedom in this material. The multiorbital nature, combined with the symmetry of the orbitals involved, leads to a plethora of exotic Cooper pairings not accessible in single-orbital systems. Essential physics is illustrated first using a two-orbital model with dxz and dyz orbitals. We classify the gap functions according to the underlying lattice symmetries, analyze the effective theories of a few representative pairings, and make connections to Sr2RuO4 in the course. In particular, we show how spin-orbit coupling may entangle spin-triplet and spin-singlet pairings. For completeness, the classification is generalized to the three-orbital model involving the dxy orbital as well. The orbital-basis approach distinguishes from the itinerant-band description for Sr2RuO4 and hence offers an alternative perspective to investigate its enigmatic superconducting state.

关键词： Pairing mechanisms Spin-singlet pairing Spin-triplet pairing Superconducting order parameter Superconductivity Topological materials Topological phases of matter Topological superconductors

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Roadmap on quantum nanotechnologies

arXiv

引用

arXiv 2021年

作者： Laucht, Arne Hohls, Frank Ubbelohde, Niels Fernando Gonzalez-Zalba, M. Reilly, David J. Stobbe, Søren Schröder, Tim Scarlino, Pasquale Koski, Jonne V. Dzurak, Andrew Yang, Chih-Hwan Yoneda, Jun Kuemmeth, Ferdinand Bluhm, Hendrik Pla, Jarryd Hill, Charles Salfi, Joe Oiwa, Akira Muhonen, Juha T. Verhagen, Ewold LaHaye, M.D. Kim, Hyun Ho Tsen, Adam W. Culcer, Dimitrie Geresdi, Attila Mol, Jan A. Mohan, Varun Jain, Prashant K. Baugh, Jonathan Centre for Quantum Computation and Communication Technology School of Electrical Engineering and Telecommunications UNSW SydneyNSW2052 Australia Physikalisch-Technische Bundesanstalt Braunschweig38116 Germany Quantum Motion Technologies Nexus Discovery Way LeedsLS2 3AA United Kingdom School of Physics University of Sydney SydneyNSW2006 Australia Microsoft Corporation Station Q Sydney University of Sydney SydneyNSW2006 Australia Department of Photonics Engineering DTU Fotonik Technical University of Denmark Building 343 Kgs. LyngbyDK-2800 Denmark Department of Physics Humboldt-Universität zu Berlin Berlin12489 Germany Department of Physics ETH Zürich ZürichCH-8093 Switzerland Niels Bohr Institute University of Copenhagen Copenhagen2100 Denmark JARA-FIT Institute for Quantum Information RWTH Aachen University and Forschungszentrum Jülich Aachen52074 Germany School of Physics University of Melbourne Melbourne Australia Department of Electrical and Computer Engineering The University of British Columbia VancouverBCV6T 1Z4 Canada The Institute of Scientific and Industrial Research Osaka University Ibaraki Osaka567-0047 Japan Center for Quantum Information and Quantum Biology Institute for open and Transdisciplinary Research Initiative Osaka University Osaka560-8531 Japan Center for Nanophotonics AMOLF Amsterdam1098 XG Netherlands School of Physics The University of New South Wales Sydney2052 Australia Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies UNSW Node The University of New South Wales Sydney2052 Australia QuTech and Kavli Institute of Nanoscience Delft University of Technology Delft2600 GA Netherlands School of Physics and Astronomy Queen Mary University of London E1 4NS United Kingdom Department of Materials Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Department of Chemistry University of Illinois at Urbana-Champaign Urbana

quantum phenomena are typically observable at length and time scales smaller than those of our everyday experience, often involving individual particles or excitations. The past few decades have seen a revolution in the ability to structure matter at the nanoscale, and experiments at the single particle level have become commonplace. This has opened wide new avenues for exploring and harnessing quantum mechanical effects in condensed matter. These quantum phenomena, in turn, have the potential to revolutionize the way we communicate, compute and probe the nanoscale world. Here, we review developments in key areas of quantum research in light of the nanotechnologies that enable them, with a view to what the future holds. Materials and devices with nanoscale features are used for quantum metrology and sensing, as building blocks for quantum computing, and as sources and detectors for quantum communication. They enable explorations of quantum behaviour and unconventional states in nano- and opto-mechanical systems, low-dimensional systems, molecular devices, nano-plasmonics, quantum electrodynamics, scanning tunnelling microscopy, and more. This rapidly expanding intersection of nanotechnology and quantum science/technology is mutually beneficial to both fields, laying claim to some of the most exciting scientific leaps of the last decade, with more on the horizon. © 2021, CC BY.

关键词： quantum computers

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Improved short-baseline neutrino oscillation search and energy spectrum measurement with the PROSPECT experiment at HFIR

引用

Physical Review D 2021年第3期103卷 032001-032001页

作者： M. Andriamirado A. B. Balantekin H. R. Band C. D. Bass D. E. Bergeron D. Berish N. S. Bowden J. P. Brodsky C. D. Bryan T. Classen A. J. Conant G. Deichert M. V. Diwan M. J. Dolinski A. Erickson B. T. Foust J. K. Gaison A. Galindo-Uribarri C. E. Gilbert B. W. Goddard B. T. Hackett S. Hans A. B. Hansell K. M. Heeger D. E. Jaffe X. Ji D. C. Jones O. Kyzylova C. E. Lane T. J. Langford J. LaRosa B. R. Littlejohn X. Lu J. Maricic M. P. Mendenhall A. M. Meyer R. Milincic I. Mitchell P. E. Mueller H. P. Mumm J. Napolitano C. Nave R. Neilson J. A. Nikkel D. Norcini S. Nour J. L. Palomino D. A. Pushin X. Qian E. Romero-Romero R. Rosero P. T. Surukuchi M. A. Tyra R. L. Varner D. Venegas-Vargas P. B. Weatherly C. White J. Wilhelmi A. Woolverton M. Yeh A. Zhang C. Zhang X. Zhang Department of Physics Illinois Institute of Technology Chicago Illinois USA Department of Physics University of Wisconsin Madison Madison Wisconsin USA Wright Laboratory Department of Physics Yale University New Haven Connecticut USA Department of Physics Le Moyne College Syracuse New York USA National Institute of Standards and Technology Gaithersburg Maryland USA Department of Physics Temple University Philadelphia Pennsylvania USA Nuclear and Chemical Sciences Division Lawrence Livermore National Laboratory Livermore California USA High Flux Isotope Reactor Oak Ridge National Laboratory Oak Ridge Tennessee USA George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia USA Brookhaven National Laboratory Upton New York USA Department of Physics Drexel University Philadelphia Pennsylvania USA Physics Division Oak Ridge National Laboratory Oak Ridge Tennessee USA Department of Physics and Astronomy University of Tennessee Knoxville Tennessee USA Department of Physics & Astronomy University of Hawaii Honolulu Hawaii USA Institute for Quantum Computing and Department of Physics and Astronomy University of Waterloo Waterloo Ontario Canada

We present a detailed report on sterile neutrino oscillation and U235 ν¯e energy spectrum measurement results from the PROSPECT experiment at the highly enriched High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. In 96 calendar days of data taken at an average baseline distance of 7.9 m from the center of the 85 MW HFIR core, the PROSPECT detector has observed more than 50,000 interactions of ν¯e produced in beta decays of U235 fission products. New limits on the oscillation of ν¯e to light sterile neutrinos have been set by comparing the detected energy spectra of ten reactor-detector baselines between 6.7 and 9.2 meters. Measured differences in energy spectra between baselines show no statistically significant indication of ν¯e to sterile neutrino oscillation and disfavor the reactor antineutrino anomaly best-fit point at the 2.5σ confidence level. The reported U235 ν¯e energy spectrum measurement shows excellent agreement with energy spectrum models generated via conversion of the measured U235 beta spectrum, with a χ2/d.o.f. of 31/31. PROSPECT is able to disfavor at 2.4σ confidence level the hypothesis that U235 ν¯e are solely responsible for spectrum discrepancies between model and data obtained at commercial reactor cores. A data-model deviation in PROSPECT similar to that observed by commercial core experiments is preferred with respect to no observed deviation, at a 2.2σ confidence level.

关键词： Neutrino oscillations Nuclear reactors Neutrino detectors

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Efficient parallel linear scaling method to get the response density matrix in all-electron real-space density-functional perturbation theory

arXiv

引用

arXiv 2020年

作者： Shang, Honghui Liang, Wanzhen Zhang, Yunquan Yang, Jinlong State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials Fujian Provincial KeyLaboratory of Theoretical and Computational Chemistry Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University XiamenFujian361005 China Hefei National Laboratory for Physical Sciences at Microscale Department of Chemical Physics Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui230026 China

The real-space density-functional perturbation theory (DFPT) for the computations of the response properties with respect to the atomic displacement and homogeneous electric field perturbation has been recently developed and implemented into the all-electron, numeric atom-centered orbitals electronic structure package FHI-aims. It is found that the bottleneck for large scale applications is the computation of the response density matrix, which scales as O(N3). Here for the response properties with respect to the homogeneous electric field, we present an efficient parallel linear scaling algorithm for the response density matrix calculation. Our scheme is based on the second-order trace-correcting purification and the parallel sparse matrix-matrix multiplication algorithms. The new scheme reduces the formal scaling from O(N3) to O(N), and shows good parallel scalability over tens of thousands of cores. As demonstrated by extensive validation, we achieve a rapid computation of accurate polarizabilities using DFPT. Finally, the computational efficiency of this scheme has been illustrated by making the scaling tests and scalability tests on massively parallel computer systems. Copyright © 2020, The Authors. All rights reserved.

关键词： Matrix algebra

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Vortex end Majorana zero modes in superconducting Dirac and Weyl semimetals

arXiv

引用

arXiv 2019年

作者： Yan, Zhongbo Wu, Zhigang Huang, Wen School of Physics Sun Yat-Sen University Guangzhou510275 China Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen518055 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen518005 China

Time-reversal invariant (TRI) Dirac and Weyl semimetals in three dimensions (3D) can simultaneously host open Fermi arcs and spin-momentum locking Fermi loops on the surfaces. This observation leads us to consider the presence of s-wave superconductivity in such semimetals and to study vortex bound states associated with-flux vortex lines. We find that when the doping level is lower than a critical value, straight vortex lines terminating at surfaces with spin-momentum locking Fermi loops realize 1D topological superconductivity and harbor Majorana zero modes at their ends. Comparisons of the vortex bounds states in these semimetals to those in the topological insulators are made and the distinctions between them elucidated. By studying the tilting effect of bulk Dirac and Weyl cones, we further find that type-I Dirac and Weyl semimetals in general have a much broader topological regime than type-II ones. Our findings build up a connection between TRI Dirac and Weyl semimetals and Majorana zero modes in vortices. Copyright © 2019, The Authors. All rights reserved.

关键词： Vortex flow

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Physical Layer Security Protocol for Poisson Channels for Passive Man-in-the-middle Attack

arXiv

引用

arXiv 2019年

作者： Hayashi, Masahito Vázquez-Castro, Ángeles Graduate School of Mathematics Nagoya University Nagoya Japan Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen China Center for Quantum Computing Peng Cheng Laboratory Shenzhen China Centre for Quantum Technologies National University of Singapore Singapore Singapore Department of Telecommunications and Systems Engineering Autonomous University of Barcelona Barcelona Spain

In this work, we focus on the classical optical channel having Poissonian statistical behavior and propose a novel secrecy coding-based physical layer protocol. Our protocol is different but complementary to both (computationally secure) quantum immune cryptographic protocols and (information theoretically secure) quantum cryptographic protocols. Specifically, our (information theoretical) secrecy coding protocol secures classical digital information bits at photonic level exploiting the random nature of the Poisson channel. It is known that secrecy coding techniques for the Poisson channel based on the classical one-way wiretap channel (introduced by Wyner in 1975) ensure secret communication only if the mutual information to the eavesdropper is smaller than that to the legitimate receiver. In order to overcome such a strong limitation, we introduce a two-way protocol that always ensures secret communication independently of the conditions of legitimate and eavesdropper channels. We prove this claim showing rigorous comparative derivation and analysis of the information theoretical secrecy capacity of the classical one-way and of the proposed two-way protocols. We also show numerical calculations that prove drastic gains and strong practical potential of our proposed two-way protocol to secure information transmission over optical channels. Copyright © 2019, The Authors. All rights reserved.

关键词： quantum cryptography

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