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Customized quantum Annealing Schedules

Physical Review Applied 2022年第4期17卷 044005-044005页

作者： Mostafa Khezri Xi Dai Rui Yang Tameem Albash Adrian Lupascu Daniel A. Lidar Department of Electrical Engineering University of Southern California Los Angeles California 90089 USA Center for Quantum Information Science & Technology University of Southern California Los Angeles California 90089 USA Department of Physics and Astronomy University of Waterloo Waterloo Ontario Canada Institute for Quantum Computing University of Waterloo Waterloo Ontario Canada Department of Electrical and Computer Engineering University of New Mexico Albuquerque New Mexico 87131 USA Center for Quantum Information and Control CQuIC University of New Mexico Albuquerque New Mexico 87131 USA Department of Chemistry University of Southern California Los Angeles California 90089 USA Department of Physics University of Southern California Los Angeles California 90089 USA

In a typical quantum annealing protocol, the system starts with a transverse field Hamiltonian that 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, 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.

关键词： Adiabatic quantum optimization quantum control quantum information with solid state qubits quantum protocols Superconducting qubits

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Enabling Large-Scale and High-Precision Fluid Simulations on Near-Term quantum Computers

arXiv

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arXiv 2024年

作者： Chen, Zhao-Yun Ma, Teng-Yang Ye, Chuang-Chao Xu, Liang Tan, Ming-Yang Zhuang, Xi-Ning Xu, Xiao-Fan Wang, Yun-Jie Sun, Tai-Ping Chen, Yong Du, Lei Guo, Liang-Liang Zhang, Hai-Feng Tao, Hao-Ran Wang, Tian-Le Yang, Xiao-Yan Zhao, Ze-An Wang, Peng Zhang, Sheng Zhang, Chi Zhao, Ren-Ze Jia, Zhi-Long Kong, Wei-Cheng Dou, Meng-Han Wang, Jun-Chao Liu, Huan-Yu Xue, Cheng Zhang, Peng-Jun-Yi Huang, Sheng-Hong Duan, Peng Wu, Yu-Chun Guo, Guo-Ping Institute of Artificial Intelligence Hefei Comprehensive National Science Center Hefei230088 China Co. Ltd. Hefei230088 China China Academy of Aerospace Aerodynamics Beijing100074 China Department of Modern Mechanics University of Science and Technology of China Hefei230026 China CAS Key Laboratory of Quantum Information University of Science and Technology of China Jinzhai Road 92 Hefei230026 China Laboratory for Advanced Computing and Intelligence Engineering Zhengzhou450000 China CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of China Hefei230026 China

quantum computational fluid dynamics (QCFD) offers a promising alternative to classical computational fluid dynamics (CFD) by leveraging quantum algorithms for higher efficiency. This paper introduces a comprehensive QCFD method implemented on a superconducting quantum computer, demonstrating successful simulations of steady Poiseuille flow and unsteady acoustic wave propagation. The Poiseuille flow simulation achieved a relative error of less than 0.2%, and the unsteady acoustic wave simulation solved a 5043-dimension matrix, marking the largest fluid simulation on a quantum computer to date. Our approach bridges quantum and classical computing, adapting to quantum hardware constraints and offering scalable solutions for large-scale CFD problems, which paves the way for practical applications of near-term quantum computers in computational science. © 2024, CC BY-NC-SA.

关键词： Computational fluid dynamics

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Experimental implementation of an efficient test of quantumness

arXiv

引用

arXiv 2022年

作者： Lewis, Laura Zhu, Daiwei Gheorghiu, Alexandru Noel, Crystal Katz, Or Harraz, Bahaa Wang, Qingfeng Risinger, Andrew Feng, Lei Biswas, Debopriyo Egan, Laird Vidick, Thomas Cetina, Marko Monroe, Christopher Institute for Quantum Information and Matter Department of Computing and Mathematical Sciences California Institute of Technology CA91125 United States Division of Physics Mathematics and Astronomy California Institute of Technology CA91125 United States 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 IonQ Inc. College ParkMD20740 United States Departments of Electrical and Computer Engineering University of Maryland College ParkMD20742 United States Institute for Theoretical Studies ETH Zürich CH 8001 Switzerland Duke Quantum Center Department of Physics Duke University DurhamNC27708 United States Department of Electrical and Computer Engineering Duke University DurhamNC27708 United States Chemical Physics Program Institute for Physical Science and Technology University of Maryland College ParkMD20742 United States

A test of quantumness is a protocol where a classical user issues challenges to a quantum device to determine if it exhibits non-classical behavior, under certain cryptographic assumptions. Recent attempts to implement such tests on current quantum computers rely on either interactive challenges with efficient verification, or non-interactive challenges with inefficient (exponential time) verification. In this paper, we execute an efficient non-interactive test of quantumness on an ion-trap quantum computer. Our results significantly exceed the bound for a classical device’s success. Copyright © 2022, The Authors. All rights reserved.

关键词： Qubits

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Polynomial representation of general partial Boolean functions with a single quantum query

arXiv

引用

arXiv 2021年

作者： Guoliang, Xu Daowen, Qiu College of Information Technology Luoyang Normal University Luoyang471934 China Institute of Quantum Computing and Computer Theory School of Computer Science and Engineering Sun Yat-Sen University Guangzhou510006 China

Early in 1992, Deutsch-Jozsa algorithm computed a symmetric partial Boolean function with a single quantum query, and thus achieved the best separation between classical deterministic and exact quantum query complexity. Until recent years, it was clarified that all symmetric partial Boolean functions with a single quantum query can be computed exactly by Deutsch-Jozsa algorithm. For the general partial Boolean functions with a single quantum query, the latest characterizations is complex and not very satisfactory. Based on this, this paper proves and discovers three new results: (1) Establishing a new equivalence, each partial Boolean function with a single quantum query can be transformed to a simple partial Boolean function whose polynomial degree is just one;(2) For partial Boolean functions up to four bits, there are only 10 non-trivial partial Boolean functions with a single quantum query;(3) For each quantum 1-query algorithm with undefined measurement, there exists a constructive method for finding out all partial Boolean functions that can be computed exactly by the algorithm. Essentially, the first discovery represent a step forward for a fundamental conclusion that the polynomial degree of partial Boolean functions with a single quantum query is one or two, and the last two results contribute a way for searching more nontrival partial Boolean functions that have quantum advantages. Copyright © 2021, The Authors. All rights reserved.

关键词： quantum computers

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Dynamics and Resonance Fluorescence from a Superconducting Artificial Atom Doubly Driven by Quantized and Classical Fields

arXiv

引用

arXiv 2024年

作者： Ruan, Xinhui Wang, Jia-Heng He, Dong Song, Pengtao Li, Shengyong Zhao, Qianchuan Kuang, L.M. Tsai, Jaw-Shen Zou, Chang-Ling Zhang, Jing Zheng, Dongning Astafiev, O.V. Liu, Yu-Xi Peng, Zhihui Department of Automation Tsinghua University Beijing100084 China Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innovation Center of Quantum Effects and Applications Hunan Normal University Changsha410081 China School of Integrated Circuits Tsinghua University Beijing100084 China Institute of Physics Chinese Academy of Sciences Beijing100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing100190 China Center for Quantum Computing RIKEN Saitama351-0198 Japan Graduate School of Science Tokyo University of Science 1-3 Kagurazaka Shinjuku Tokyo162-0825 Japan CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei Anhui230026 China Hefei National Laboratory Hefei230088 China School of Automation Science and Engineering Xi'an Jiaotong University Xi’an710049 China MOE Key Lab for Intelligent Networks and Network Security Xi'an Jiaotong University Xi’an710049 China Skolkovo Institute of Science and Technology Nobel str. 3 Moscow143026 Russia Moscow Institute of Physics and Technology Institutskiy Pereulok 9 Dolgoprudny141701 Russia Royal Holloway University of London Surrey EghamTW20 0EX United Kingdom

We report an experimental demonstration of resonance fluorescence in a two-level superconducting artificial atom under two driving fields coupled to a detuned cavity. One of the fields is classical and the other is varied from quantum (vacuum fluctuations) to classical one by controlling the photon number inside the cavity. The device consists of a transmon qubit strongly coupled to a one-dimensional transmission line and a coplanar waveguide resonator. We observe a sideband anti-crossing and asymmetry in the emission spectra of the system through a one-dimensional transmission line, which is fundamentally different from the weak coupling case. By changing the photon number inside the cavity, the emission spectrum of our doubly driven system approaches to the case when the atom is driven by two classical bichromatic fields. We also measure the dynamical evolution of the system through the transmission line and study the properties of the first-order correlation function, Rabi oscillations and energy relaxation in the system. The study of resonance fluorescence from an atom driven by two fields promotes understanding decoherence in superconducting quantum circuits and may find applications in superconducting quantum computing and quantum networks. Copyright © 2024, The Authors. All rights reserved.

关键词： Electric lines

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The reservoir learning power across quantum many-boby localization transition

arXiv

引用

arXiv 2021年

作者： Xia, Wei Zou, Jie Qiu, Xingze Li, Xiaopeng State Key Laboratory of Surface Physics Institute of Nanoelectronics and Quantum Computing Department of Physics Fudan University Shanghai200433 China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Shanghai Qi Zhi Institute AI Tower Xuhui District Shanghai200232 China

Harnessing the quantum computation power of the present noisy-intermediate-size-quantum devices has received tremendous interest in the last few years. Here we study the learning power of a one-dimensional long-range randomly-coupled quantum spin chain, within the framework of reservoir computing. In time sequence learning tasks, we find the system in the quantum many-body localized (MBL) phase holds long-term memory, which can be attributed to the emergent local integrals of motion. On the other hand, MBL phase does not provide sufficient nonlinearity in learning highly-nonlinear time sequences, which we show in a parity check task. This is reversed in the quantum ergodic phase, which provides sufficient nonlinearity but compromises memory capacity. In a complex learning task of Mackey-Glass prediction that requires both sufficient memory capacity and nonlinearity, we find optimal learning performance near the MBL-to-ergodic transition. This leads to a guiding principle of quantum reservoir engineering at the edge of quantum ergodicity reaching optimal learning power for generic complex reservoir learning tasks. Our theoretical finding can be readily tested with present experiments. Copyright © 2021, The Authors. All rights reserved.

关键词： quantum computers

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Probing disorder-induced time-reversal symmetry breaking in Josephson junctions

arXiv

引用

arXiv 2024年

作者： Wu, Yu Huang, Daiqiang Zhang, Huanyu Guarino, Anita Fittipaldi, Rosalba Ma, Chao Hu, Wenjie Niu, Chang Wang, Zhen Yu, Weichao Yerin, Yuriy Vecchione, Antonio Liu, Yang Cuoco, Mario Guo, Hangwen Shen, Jian State Key Laboratory of Surface Physics Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China Department of Physics Fudan University Shanghai200433 China International Center for Quantum Materials Peking University Beijing100871 China FiscianoI-84084 Italy College of Materials Science and Engineering Hunan University Changsha410082 China Department of Physics University of Science and Technology of China Anhui Hefei230026 China Zhangjiang Fudan International Innovation Center Fudan University Shanghai201210 China CNR-SPIN via del Fosso del Cavaliere 100 Roma00133 Italy Shanghai Research Center for Quantum Sciences Shanghai201315 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China

The relation between superconductivity and time-reversal symmetry (TRS) is one of the most fascinating problems in condensed matter physics. Although most superconductors inherently possess TRS, nonmagnetic disorder can induce states that demonstrate the breaking of this symmetry. Yet, the identification of experimental signatures of superconductivity with broken TRS remains a challenge. Here, we fabricate vertical Josephson junctions using metallic superconductor (Al) and ion bombarded Sr2RuO4 to study disorder-driven TRS breaking effects. We observe persistent magneto-resistive hysteresis behavior dependent on the disorder deposition time that provides evidence of TRS breaking below the superconducting transition temperature. Field and temperature dependent measurements suggest that the observed effects arise from disorder-induced anomalous flux in Sr2RuO4 surface which can be sensitively detected by superconducting Al. Our experimental results can be accounted within a physical framework of disorder-induced reconstruction of the superconducting order parameter as described within a multiband Ginzburg-Landau approach. © 2024, CC BY-NC-SA.

关键词： Ruthenium compounds

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Momentum and angular correlations in Z/γ-hadron production in relativistic heavy-ion collisions

arXiv

引用

arXiv 2023年

作者： Gao, Zhan Chen, Lin Hu, Peng-Hui Xie, Man Zhang, Han-Zhong Institute of Particle Physics Central China Normal University Wuhan430079 China School of Science and Engineering The Chinese University of Hong Kong Shenzhen518172 China University of Science and Technology of China Anhui Hefei230026 China Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter Institute of Quantum Matter South China Normal University Guangzhou510006 China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Guangdong Provincial Key Laboratory of Nuclear Science Southern Nuclear Science Computing Center South China Normal University Guangzhou510006 China

We carry out a detailed study of medium modifications on momentum and angular correlations between a large transverse momentum hadron and a Z/γ trigger in relativistic heavy-ion collisions within a perturbative QCD parton model improved by the Sudakov resummation technique. The total energy loss of a hard parton propagating inside the medium is employed to modify the fragmentation function, while the medium-induced transverse momentum broadening is included in the resummation approach, and both of them are related to the jet transport parameter and obtained by the high-twist formalism. We obtain good agreements with the existing data on transverse momentum and azimuthal angular correlations for the Z/γ-hadron pairs in pp and AA collisions, and predict the correlations for the γ-hadron in central PbPb collisions at 5.02 TeV. The numerical analyses for the Z/γ-hadron in central PbPb collisions show that the normalized angular distribution is decorrelated due to the medium-induced transverse momentum broadening, however, the angular correlation is enhanced due to the parton energy loss, namely anti-broadening. The observed modification of the angular correlation is a result of the competition between the broadening and the anti-broadening. This work provides a reliable theoretical tool for a comprehensive and precise study of jet quenching in relativistic heavy-ion collisions. © 2023, CC BY.

关键词： Angular distribution

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Experimental evidence for the two-path description of neutron spin echo

引用

Physical Review A 2024年第4期109卷 042420-042420页

作者： S. McKay A. A. M. Irfan Q. Le Thien N. Geerits S. R. Parnell R. M. Dalgliesh N. V. Lavrik I. I. Kravchenko G. Ortiz R. Pynn Department of Physics Indiana University Bloomington Indiana 47405 USA Center for Exploration of Energy and Matter Indiana University Bloomington Indiana 47408 USA Atominstitut TU Wien Stadionallee 2 1020 Vienna Austria Faculty of Applied Sciences Delft University of Technology Mekelweg 15 2629 JB Delft The Netherlands ISIS Rutherford Appleton Laboratory Chilton Oxfordshire OX11 0QX United Kingdom Center for Nanophase Materials Science Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Quantum Science and Engineering Center Indiana University Bloomington Indiana 47408 USA Institute for Quantum Computing University of Waterloo Waterloo Ontario Canada N2L 3G1 Neutron Sciences Directorate Oak Ridge National Laboratory Oak Ridge Tennessee 37830 USA

We describe an experiment that strongly supports a two-path interferometric model in which the spin-up and spin-down components of each neutron propagate coherently along spatially separated parallel paths in a typical neutron spin-echo small-angle scattering (SESANS) experiment. Specifically, we show that the usual semi-classical, single-path treatment of Larmor precession of a polarized neutron in an external magnetic field predicts a damping as a function of the spin-echo length of the SESANS signal obtained with a periodic phase grating when the transverse width of the neutron wave packet is finite. However, no such damping is observed experimentally, implying either that the Larmor model is incorrect or that the transverse extent of the wave packet is very large. In contrast, we demonstrate theoretically that a quantum-mechanical interferometric model in which the two mode-entangled (i.e., intraparticle entangled) spin states of a single neutron are separated in space when they interact with the grating accurately predicts the measured SESANS signal, which is independent of the wave packet width.

关键词： quantum entanglement Interferometry Neutron spin echo spectroscopy Spin echo small angle neutron scattering

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Terahertz Generation via Picosecond Spin-to-Charge Conversion in IrMn3/Ni−Fe Heterojunction

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Physical Review Applied 2021年第2期16卷 024058-024058页

作者： Cheng Li Bin Fang Like Zhang Qian Chen Xiangnan Xie Nuo Xu Zhongming Zeng Zhenyu Wang Liang Fang Tian Jiang Institute for Quantum Information & State Key Laboratory of High Performance Computing National University of Defense Technology Changsha 410073 China Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia Suzhou Institute of Nano-Tech and Nano-Bionics CAS Suzhou 215123 China College of Electronic and Information Engineering Wuxi University Wuxi 214105 China National Innovation Institute of Defense Technology Academy of Military Sciences PLA China Beijing 100010 China Beijing Academy of Quantum Information Sciences Beijing 100193 China Beijing Institute for Advanced Studies National University of Defense Technology 100010 China

Experimental investigations of ultrafast electro-optical properties in magnetic materials manifest their great potential for emerging spintronic optoelectronic devices. Here, using time-resolved terahertz emission spectroscopy, we construct a spintronic terahertz emitter consisting of an IrMn3/Ni−Fe heterojunction. A femtosecond spin current pulse is generated in the thin film of the Ni−Fe layer when it absorbs a femtosecond laser pulse, and then the spin current is converted into a transient charge current by the metallic IrMn3 layer on picosecond timescales. We timely record the terahertz emission associated with this ultrafast conversion process by means of electro-optic sampling. Besides, the spin-to-charge conversion efficiency of the IrMn3/Ni−Fe heterojunction is determined via quantitative analysis of the spin torque ferromagnetic resonance results. We have both optically verified and electrically studied the spin-to-charge conversion of the IrMn3/Ni−Fe heterojunction. Our results enlarge the material choice range of spintronic terahertz emitters, which may promote further investigations of ultrafast spin-to-charge conversion in different heterojunction materials.

关键词： Magnetization dynamics Optical sources & detectors Optoelectronics Spin current Spin-orbit coupling Ultrafast magnetic effects Magnetic multilayers Terahertz techniques

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