检索结果-内蒙古大学图书馆

arXiv 2020年

作者： Zhang, Xin Zhou, Yuan Hu, Rui-Zi Ma, Rong-Long Ni, Ming Wang, Ke Luo, Gang Cao, Gang Wang, Gui-Lei Huang, Peihao Hu, Xuedong Jiang, Hong-Wen Li, Hai-Ou Guo, Guang-Can Guo, Guo-Ping CAS Key Laboratory of Quantum Information University of Science and Technology of China Anhui Hefei230026 China CAS Center for Excellence Synergetic Innovation Center in Quantum Information and Quantum Physics University of Science and Technology of China Anhui Hefei230026 China Key Laboratory of Microelectronics Devices & Integrated Technology Institute of Microelectronics Chinese Academy of Sciences Beijing100029 China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Guangdong Provincial Key Laboratory of Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Department of Physics University at Buffalo SUNY BuffaloNY14260 United States Department of Physics and Astronomy University of California Los AngelesCA90095 United States Origin Quantum Computing Company Limited Anhui Hefei230026 China

Tunable synthetic spin-orbit coupling (s-SOC) is one of the key challenges in various quantum systems, such as ultracold atomic gases, topological superconductors, and semiconductor quantum dots. Here we experimentally demonstrate controlling the s-SOC by investigating the anisotropy of spin-valley resonance in a silicon quantum dot. As we rotate the applied magnetic field in-plane, we find a striking nonsinusoidal behavior of resonance amplitude that distinguishes s-SOC from the intrinsic spin-orbit coupling (i-SOC), and associate this behavior with the previously overlooked in-plane transverse magnetic field gradient. Moreover, by theoretically analyzing the experimentally measured s-SOC field, we predict the quality factor of the spin qubit could be optimized if the orientation of the in-plane magnetic field is rotated away from the traditional working point. Copyright © 2020, The Authors. All rights reserved.

关键词： Semiconductor quantum dots

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Customized quantum annealing schedules

arXiv

引用

arXiv 2021年

作者： Khezri, Mostafa Dai, Xi Yang, Rui Albash, Tameem Lupascu, Adrian Lidar, Daniel A. Department of Electrical Engineering University of Southern California Los AngelesCA90089 United States Center for Quantum Information Science & Technology University of Southern California Los AngelesCA90089 United States Department of Physics and Astronomy University of Waterloo WaterlooON Canada Institute for Quantum Computing University of Waterloo WaterlooON Canada Department of Electrical and Computer Engineering University of New Mexico AlbuquerqueNM87131 United States Center for Quantum Information and Control CQuIC University of New Mexico AlbuquerqueNM87131 United States Department of Chemistry University of Southern California Los AngelesCA90089 United States Department of Physics University of Southern California Los AngelesCA90089 United States

In a typical quantum annealing protocol, the system starts with a transverse field Hamiltonian which is gradually turned off and replaced by a longitudinal Ising Hamiltonian. The ground state of the Ising Hamiltonian encodes the solution to the computational problem of interest, and the state overlap with this ground state gives the success probability of the annealing protocol. The form of the annealing schedule can have a significant impact on the ground state overlap at the end of the anneal, so precise control over these annealing schedules can be a powerful tool for increasing success probabilities of annealing protocols. Here we show how superconducting circuits, in particular capacitively shunted flux qubits (CSFQs), can be used to construct quantum annealing systems by providing tools for mapping circuit flux biases to Pauli coefficients. We use this mapping to find customized annealing schedules: appropriate circuit control biases that yield a desired annealing schedule, while accounting for the physical limitations of the circuitry. We then provide examples and proposals that utilize this capability to improve quantum annealing performance. Copyright © 2021, The Authors. All rights reserved.

关键词： Annealing

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Interactive Protocols for Classically-Verifiable quantum Advantage

arXiv

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arXiv 2021年

作者： Zhu, Daiwei Kahanamoku-Meyer, Gregory D. Lewis, Laura Noel, Crystal Katz, Or Harraz, Bahaa Wang, Qingfeng Risinger, Andrew Feng, Lei Biswas, Debopriyo Egan, Laird Gheorghiu, Alexandru Nam, Yunseong Vidick, Thomas Vazirani, Umesh Yao, Norman Y. Cetina, Marko Monroe, Christopher Joint Quantum Institute Departments of Physics and Electrical and Computer Engineering University of Maryland College ParkMD20742 United States Joint Center for Quantum Information and Computer Science NIST University of Maryland College ParkMD20742 United States Department of Physics University of California BerkeleyCA94720 United States Materials Sciences Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Computing and Mathematical Sciences California Institute of Technology CA91125 United States Division of Physics Mathematics and Astronomy California Institute of Technology CA91125-0001 United States Duke Quantum Center Department of Physics Duke University DurhamNC27708 United States Department of Electrical and Computer Engineering Duke University DurhamNC27708 United States IonQ Inc. College ParkMD20740 United States Institute for Theoretical Studies ETH Zürich CH 8001 Switzerland Chemical Physics Program Institute for Physical Science and Technology University of Maryland College ParkMD20742 United States Departments of Electrical and Computer Engineering University of Maryland College ParkMD20742 United States

Interaction is a powerful resource for quantum computation. It can be utilized in applications ranging from the verification of quantum algorithms all the way to verifying quantum mechanics itself. Here, we present the first implementation of interactive protocols for proofs of quantumness — which when suitably scaled promise the efficient verification of quantum computational advantage. The key feature that distinguishes these protocols from existing demonstrations of quantum advantage is that the classical verification is efficient and scales polynomially rather than exponentially with the number of qubits. The experimental implementation of such interactive protocols requires the ability to independently measure subsets of qubits in the middle of a quantum circuit and to continue coherent evolution afterwards. This is achieved by spatially isolating target qubits via shuttling, and opens the door to a range of quantum interactive protocols as well as new information processing architectures. Copyright © 2021, The Authors. All rights reserved.

关键词： Qubits

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Final Measurement of the U235 Antineutrino Energy Spectrum with the PROSPECT-I Detector at HFIR

引用

Physical Review Letters 2023年第2期131卷 021802-021802页

作者： M. Andriamirado A. B. Balantekin C. D. Bass D. E. Bergeron E. P. Bernard N. S. Bowden C. D. Bryan R. Carr T. Classen A. J. Conant G. Deichert A. Delgado M. V. Diwan M. J. Dolinski A. Erickson B. T. Foust J. K. Gaison A. Galindo-Uribari C. E. Gilbert S. Gokhale C. Grant S. Hans A. B. Hansell K. M. Heeger B. Heffron D. E. Jaffe S. Jayakumar X. Ji D. C. Jones J. Koblanski P. Kunkle O. Kyzylova D. LaBelle C. E. Lane T. J. Langford J. LaRosa B. R. Littlejohn X. Lu J. Maricic M. P. Mendenhall A. M. Meyer R. Milincic P. E. Mueller H. P. Mumm J. Napolitano R. Neilson J. A. Nikkel S. Nour J. L. Palomino Gallo D. A. Pushin X. Qian C. Roca R. Rosero M. Searles P. T. Surukuchi F. Sutanto M. A. Tyra D. Venegas-Vargas P. B. Weatherly J. Wilhelmi A. Woolverton M. Yeh C. Zhang X. Zhang Department of Physics Illinois Institute of Technology Chicago Illinois 60616 USA Department of Physics University of Wisconsin Madison Wisconsin 53706 USA Department of Physics Le Moyne College Syracuse New York 13214 USA National Institute of Standards and Technology Gaithersburg Maryland 20899 USA Nuclear and Chemical Sciences Division Lawrence Livermore National Laboratory Livermore California 94550 USA High Flux Isotope Reactor Oak Ridge National Laboratory Oak Ridge Tennessee USA Department of Physics United States Naval Academy Annapolis Maryland 21402 USA Physics Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Brookhaven National Laboratory Upton New York 11973 USA Department of Physics Drexel University Philadelphia PA 19104-2875 Pennsylvania USA George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 USA Wright Laboratory Department of Physics Yale University New Haven Connecticut 06520 USA Department of Physics and Astronomy University of Tennessee Knoxville Tennessee 37916 USA Department of Physics Boston University Boston Massachusetts 02215 USA Department of Physics Susquehanna University Selinsgrove Pennsylvania 17870 USA Department of Physics (035-08) Temple University 1925 N 12th Street Philadelphia Pennsylvania 19122-1801 USA Department of Physics and Astronomy University of Hawaii Honolulu Hawaii 96822 USA Institute for Quantum Computing and Department of Physics University of Waterloo Waterloo ON N2L 3G1 Ontario Canada

This Letter reports one of the most precise measurements to date of the antineutrino spectrum from a purely U235-fueled reactor, made with the final dataset from the PROSPECT-I detector at the High Flux Isotope Reactor. By extracting information from previously unused detector segments, this analysis effectively doubles the statistics of the previous PROSPECT measurement. The reconstructed energy spectrum is unfolded into antineutrino energy and compared with both the Huber-Mueller model and a spectrum from a commercial reactor burning multiple fuel isotopes. A local excess over the model is observed in the 5–7 MeV energy region. Comparison of the PROSPECT results with those from commercial reactors provides new constraints on the origin of this excess, disfavoring at 2.0 and 3.7 standard deviations the hypotheses that antineutrinos from U235 are solely responsible and noncontributors to the excess observed at commercial reactors, respectively.

关键词： Fission Neutrino interactions Nuclear reactors Neutrinos Neutrino detectors Scintillators

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First-step experiment in developing optical-spring quantum locking for DECIGO: sensitivity optimization for simulated quantum noise by completing the square

arXiv

引用

arXiv 2022年

作者： Ishikawa, Tomohiro Kawasaki, Yuki Tsuji, Kenji Yamada, Rika Watanabe, Izumi Wu, Bin Iwaguchi, Shoki Shimizu, Ryuma Umemura, Kurumi Nagano, Koji Enomoto, Yutaro Komori, Kentaro Michimura, Yuta Furusawa, Akira Kawamura, Seiji Department of Physics Nagoya University Aichi Nagoya464-8602 Japan Institute of Space and Astronautical Science Japan Aerospace Exploration Agency Kanagawa Sagamihara252-5210 Japan Department of Applied Physics School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan Department of Physics University of Tokyo Bunkyo Tokyo113-0033 Japan LIGO Laboratory California Institute of Technology PasadenaCA91125 United States Graduate School of Science University of Tokyo Bunkyo Tokyo113-0033 Japan Center for Quantum Computing RIKEN 2-1 Hirosawa Saitama Wako351-0198 Japan The Kobayashi-Maskawa Institute for the Origin of Particles and the Universe Nagoya University Aichi Nagoya464-8602 Japan

DECi-hertz Interferometer Gravitational Wave Observatory (DECIGO) is a future mission for a space-borne laser interferometer. DECIGO has 1,000-km-long arm cavities mainly to detect the primordial gravitational waves (PGW) at lower frequencies around 0.1 Hz. Observations in the electromagnetic spectrum have lowered the bounds on the upper limit of PGW energy density (Ωgw ∼ 10−15 → 10−16). As a result, DECIGO’s target sensitivity, which is mainly limited by quantum noise, needs further improvement. To maximize the feasibility of detection while constrained by DECIGO’s large diffraction loss, a quantum locking technique with an optical spring was theoretically proposed to improve the signal-to-noise ratio of the PGW. In this paper, we experimentally verify one key element of the optical-spring quantum locking: sensitivity optimization by completing the square of multiple detector outputs. This experiment is operated on a simplified tabletop optical setup with classical noise simulating quantum noise. We succeed in getting the best of the sensitivities with two different laser powers by the square completion method. © 2022, CC BY.

关键词： Gravity waves

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Naive lattice fermion without doublers

arXiv

引用

arXiv 2021年

作者： Guo, Xingyu Ma, Chen-Te Zhang, Hui Guangdong Provincial Key Laboratory of Nuclear Science Institute of Quantum Matter South China Normal University Guangzhou510006 China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Southern Nuclear Science Computing Center South China Normal University Guangzhou510006 China Asia Pacific Center for Theoretical Physics Pohang University of Science and Technology Gyeongsangbuk-do Pohang37673 Korea Republic of School of Physics and Telecommunication Engineering South China Normal University Guangdong Guangzhou510006 China The Laboratory for Quantum Gravity and Strings Department of Mathematics and Applied Mathematics University of Cape Town Private Bag Rondebosch7700 South Africa

We discuss the naive lattice fermion without the issue of doublers. A local lattice massless fermion action with chiral symmetry and hermiticity cannot avoid the doubling problem from the Nielsen-Ninomiya theorem. Here we adopt the forward finite-difference deforming the γ5-hermiticity but preserving the continuum chiral-symmetry. The lattice momentum is not hermitian without the continuum limit now. We demonstrate that there is no doubling issue from an exact solution. The propagator only has one pole in the first-order accuracy. Therefore, it is hard to know the avoiding due to the non-hermiticity. For the second-order, the lattice propagator has two poles as before. This case also does not suffer from the doubling problem. Hence separating the forward derivative from the backward one evades the doublers under the field theory limit. Simultaneously, it is equivalent to breaking the hermiticity. In the end, we discuss the topological charge and also demonstrate the numerical implementation of the Hybrid Monte Carlo. Copyright © 2021, The Authors. All rights reserved.

关键词： Poles

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Pseudo landau levels, negative strain resistivity, and enhanced thermopower in twisted graphene nanoribbons

arXiv

引用

arXiv 2020年

作者： Shi, Zheng Lu, Hai-Zhou Liu, Tianyu Dahlem Center for Complex Quantum Systems and Physics Department Freie Universität Berlin Berlin14195 Germany Institute for Quantum Computing Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Institute for Quantum Science and Engineering Department of Physics Southern University of Science and Technology Shenzhen518055 China Shenzhen Key Laboratory of Quantum Science and Engineering Shenzhen518055 China Max-Planck-Institut für Physik komplexer Systeme Dresden01187 Germany

As a canonical response to the applied magnetic field, the electronic states of a metal are fundamentally reorganized into Landau levels. In Dirac metals, Landau levels can be expected without magnetic fields, provided that an inhomogeneous strain is applied to spatially modulate electron hoppings in a way similar to the Aharonov-Bohm phase. We here predict that a twisted zigzag nanoribbon of graphene exhibits strain-induced pseudo Landau levels of unexplored but analytically solvable dispersions at low energies. The presence of such dispersive pseudo Landau levels results in a negative strain resistivity characterizing the (1 + 1)-dimensional chiral anomaly if partially filled and can greatly enhance the thermopower when fully filled. Copyright © 2020, The Authors. All rights reserved.

关键词： Graphene

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Skyrmion alignment and pinning effects in the disordered multiphase skyrmion material Co8Zn8Mn4

引用

Physical Review B 2022年第9期106卷 094435-094435页

作者： M. E. Henderson M. Bleuel J. Beare D. G. Cory B. Heacock M. G. Huber G. M. Luke M. Pula D. Sarenac S. Sharma E. M. Smith K. Zhernenkov D. A. Pushin Institute for Quantum Computing University of Waterloo Waterloo Ontario Canada N2L3G1 Department of Physics & Astronomy University of Waterloo Waterloo Ontario Canada N2L3G1 National Institute of Standards and Technology Gaithersburg Maryland 20899-8970 USA Department of Materials Science and Engineering University of Maryland College Park Maryland 20742-2115 USA Department of Physics and Astronomy McMaster University Hamilton Ontario Canada L8S 4M1 Department of Chemistry University of Waterloo Waterloo Ontario Canada N2L3G1 Brockhouse Institute for Materials Research Hamilton Ontario Canada L8S 4M1 Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum Forschungszentrum Jülich GmbH 85748 Garching Germany

Underlying disorder in skyrmion materials may both inhibit and facilitate skyrmion reorientations and changes in topology. The identification of these disorder-induced topologically active regimes is critical to realizing robust skyrmion spintronic implementations, yet few studies exist for disordered bulk samples. Here, we employ small-angle neutron scattering (SANS) and micromagnetic simulations to examine the influence of skyrmion order on skyrmion lattice formation, transition, and reorientation dynamics across the phase space of a disordered polycrystalline Co8Zn8Mn4 bulk sample. Our measurements reveal a disordered-to-ordered skyrmion square lattice transition pathway characterized by the promotion of fourfold order in SANS and accompanied by a change in topology of the system, reinforced through micromagnetic simulations. Pinning responses are observed to dominate skyrmion dynamics in the metastable triangular lattice phase, enhancing skyrmion stabilization through a remarkable skyrmion memory effect which reproduces previous ordering processes and persists in zero field. These results uncover the cooperative interplay of anisotropy and disorder in skyrmion formation and restructuring dynamics, establishing tunable pathways for skyrmion manipulation.

关键词： Magnetic order Magnetic phase transitions Magnetic texture Magnetism Skyrmions Spintronics Topological materials

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Effects of biased and unbiased illuminations on two-dimensional electron gases in dopant-free GaAs/AlGaAs

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Physical Review B 2022年第7期105卷 075302-075302页

作者： A. Shetty F. Sfigakis W. Y. Mak K. Das Gupta B. Buonacorsi M. C. Tam H. S. Kim I. Farrer A. F. Croxall H. E. Beere A. R. Hamilton M. Pepper D. G. Austing S. A. Studenikin A. Sachrajda M. E. Reimer Z. R. Wasilewski D. A. Ritchie J. Baugh Institute for Quantum Computing University of Waterloo Waterloo N2L 3G1 Canada Department of Chemistry University of Waterloo Waterloo N2L 3G1 Canada Cavendish Laboratory University of Cambridge Cambridge CB3 0HE United Kingdom Northern Quantum Lights Inc. Waterloo N2B 1N5 Canada Department of Physics Indian Institute of Technology Bombay Mumbai 40007 India Department of Physics and Astronomy University of Waterloo Waterloo N2L 3G1 Canada Department of Electrical and Computer Engineering University of Waterloo Waterloo N2L 3G1 Canada Department of Electronic and Electrical Engineering University of Sheffield Sheffield S1 3JD United Kingdom School of Physics University of New South Wales Sydney NSW 2052 Australia Department of Electronic and Electrical Engineering University College London London WC1E 7JE United Kingdom Security and Disruptive Technologies Research Centre National Research Council of Canada Ottawa K1A 0R6 Canada Waterloo Institute for Nanotechnology University of Waterloo Waterloo N2L 3G1 Canada

Illumination is performed at low temperature on dopant-free two-dimensional electron gases (2DEGs) of varying depths, under unbiased (gates grounded) and biased (gates at a positive or negative voltage) conditions. Unbiased illuminations in 2DEGs located more than 70 nm away from the surface result in a gain in mobility at a given electron density, primarily driven by the reduction of background impurities. In 2DEGs closer to the surface, unbiased illuminations result in a mobility loss, driven by an increase in surface charge density. Biased illuminations performed with positive applied gate voltages result in a mobility gain, whereas those performed with negative applied voltages result in a mobility loss. The magnitude of the mobility gain (loss) weakens with 2DEG depth, and is likely driven by a reduction (increase) in surface charge density. Remarkably, this mobility gain/loss is fully reversible by performing another biased illumination with the appropriate gate voltage, provided both n-type and p-type Ohmic contacts are present. Experimental results are modeled with Boltzmann transport theory, and possible mechanisms are discussed.

关键词： Photoinduced effect quantum transport Field-effect transistors III-V semiconductors Two-dimensional electron gas Boltzmann theory Hall bar Molecular beam epitaxy

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Towards provably efficient quantum algorithms for large-scale machine-learning models

arXiv

引用

arXiv 2023年

作者： Liu, Junyu Liu, Minzhao Liu, Jin-Peng Ye, Ziyu Wang, Yunfei Alexeev, Yuri Eisert, Jens Jiang, Liang Pritzker School of Molecular Engineering The University of Chicago ChicagoIL60637 United States Department of Computer Science The University of Chicago ChicagoIL60637 United States Chicago Quantum Exchange ChicagoIL60637 United States Kadanoff Center for Theoretical Physics The University of Chicago ChicagoIL60637 United States qBraid Co. ChicagoIL60615 United States SeQure ChicagoIL60615 United States Department of Physics The University of Chicago ChicagoIL60637 United States Computational Science Division Argonne National Laboratory LemontIL60439 United States Simons Institute for the Theory of Computing University of California BerkeleyCA94720 United States Department of Mathematics University of California BerkeleyCA94720 United States Center for Theoretical Physics Massachusetts Institute of Technology CambridgeMA02139 United States Martin A. Fisher School of Physics Brandeis University WalthamMA02453 United States Dahlem Center for Complex Quantum Systems Free University Berlin Berlin14195 Germany

Large machine learning models are revolutionary technologies of artificial intelligence whose bottlenecks include huge computational expenses, power, and time used both in the pre-training and fine-tuning process. In this work, we show that fault-tolerant quantum computing could possibly provide provably efficient resolutions for generic (stochastic) gradient descent algorithms, scaling as O(T2 × polylog(n)), where n is the size of the models and T is the number of iterations in the training, as long as the models are both sufficiently dissipative and sparse, with small learning rates. Based on earlier efficient quantum algorithms for dissipative differential equations, we find and prove that similar algorithms work for (stochastic) gradient descent, the primary algorithm for machine learning. In practice, we benchmark instances of large machine learning models from 7 million to 103 million parameters. We find that, in the context of sparse training, a quantum enhancement is possible at the early stage of learning after model pruning, motivating a sparse parameter download and re-upload scheme. Our work shows solidly that faulttolerant quantum algorithms could potentially contribute to most state-of-the-art, large-scale machine-learning problems. Copyright © 2023, The Authors. All rights reserved.

关键词： Differential equations

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