In the effort to develop useful quantum computers,simulating quantum machines with conventional classical computing resources is a key capability.Such simulations will always face limits,preventing the emulation of qu...In the effort to develop useful quantum computers,simulating quantum machines with conventional classical computing resources is a key capability.Such simulations will always face limits,preventing the emulation of quantum computers at substantial scale;however,by pushing the envelope through optimal choices of algorithms and hardware,the value of simulator tools can be maximized.This work reviews state-of-the-art numerical simulation methods,i.e.,classical algorithms that emulate quantum computer evolution under specific operations.We focus on the mainstream state-vector and tensor-network paradigms,while briefly mentioning alternative methods.Moreover,we review the diverse applications of simulation across different facets of quantum computer development,including understanding the fundamental differences between quantum and classical computations,exploring algorithmic design for quantum advantage,predicting quantum processor performance at the design stage,and efficiently characterizing fabricated devices for rapid iterations.This review complements recent surveys of current tools and implementations;here,we aim to provide readers with an essential understanding of the theoretical basis of classical simulation methods,a detailed discussion of their advantages and limitations,and an overview of the demands and challenges arising from practical use cases.展开更多
The elucidation of the multi-scale transport phenomena of lithium ions in solid electrolyte under working conditions poses huge challenges to both experimental and theoretical realms.Highresolution ab initio molecular...The elucidation of the multi-scale transport phenomena of lithium ions in solid electrolyte under working conditions poses huge challenges to both experimental and theoretical realms.Highresolution ab initio molecular dynamics simulations are severely limited by spatial and temporal scales,hindering direct comparisons with experimental observations under room temperature and applied electric potential.Herein,classical molecular dynamics simulations under constant potential are employed to unveil the migration mechanism of Li-ions in Li_(6)PS_(5)Cl(LPSC)confined by electrode interfaces considering realistic conditions.By sophisticated manipulation of anion compositions in LPSC electrolyte,it is observed that neighboring vacancies provide effective pathways for Li-ions migration and the coordination environments evolves progressively with increasing diffusion coefficient,while the conductivity exhibits a non-monotonic peak in Li_(5.3)PS_(4.3)Cl_(1.7).The semiquantitative agreement with existing experimental resultsdemonstrates the superiority of our constant potential solid electrolytemodel,which weexpect to provide atomistic understanding towards rational design of solid electrolyte.展开更多
Quantum computing is a game-changing technology for global academia,research centers and industries including computational science,mathematics,finance,pharmaceutical,materials science,chemistry and cryptography.Altho...Quantum computing is a game-changing technology for global academia,research centers and industries including computational science,mathematics,finance,pharmaceutical,materials science,chemistry and cryptography.Although it has seen a major boost in the last decade,we are still a long way from reaching the maturity of a full-fledged quantum computer.That said,we will be in the noisy-intermediate scale quantum(NISQ)era for a long time,working on dozens or even thousands of qubits quantum computing systems.An outstanding challenge,then,is to come up with an application that can reliably carry out a nontrivial task of interest on the near-term quantum devices with non-negligible quantum noise.To address this challenge,several near-term quantum computing techniques,including variational quantum algorithms,error mitigation,quantum circuit compilation and benchmarking protocols,have been proposed to characterize and mitigate errors,and to implement algorithms with a certain resistance to noise,so as to enhance the capabilities of near-term quantum devices and explore the boundaries of their ability to realize useful applications.Besides,the development of near-term quantum devices is inseparable from the efficient classical sim-ulation,which plays a vital role in quantum algorithm design and verification,error-tolerant verification and other applications.This review will provide a thorough introduction of these near-term quantum computing techniques,report on their progress,and finally discuss the future prospect of these techniques,which we hope will motivate researchers to undertake additional studies in this field.展开更多
Gaussian boson sampling is an alternative model for demonstrating quantum computational supremacy,where squeezed states are injected into every input mode, instead of applying single photons as in the case of standard...Gaussian boson sampling is an alternative model for demonstrating quantum computational supremacy,where squeezed states are injected into every input mode, instead of applying single photons as in the case of standard boson sampling. Here by analyzing numerically the computational costs, we establish a lower bound for achieving quantum computational supremacy for a class of Gaussian bosonsampling problems. Specifically, we propose a more efficient method for calculating the transition probabilities, leading to a significant reduction of the simulation costs. Particularly, our numerical results indicate that one can simulate up to 18 photons for Gaussian boson sampling at the output subspace on a normal laptop, 20 photons on a commercial workstation with 256 cores, and about 30 photons for supercomputers. These numbers are significantly smaller than those in standard boson sampling, suggesting that Gaussian boson sampling could be experimentally-friendly for demonstrating quantum computational supremacy.展开更多
We study the double ionization dynamics of a helium atom impacted by electrons with full-dimensional classical trajectory Monte Carlo simulation. The excess energy is chosen to cover a wide range of values from 5 e V ...We study the double ionization dynamics of a helium atom impacted by electrons with full-dimensional classical trajectory Monte Carlo simulation. The excess energy is chosen to cover a wide range of values from 5 e V to 1 ke V for comparative study. At the lowest excess energy, i.e., close to the double-ionization threshold, it is found that the projectile momentum is totally transferred to the recoil-ion while the residual energy is randomly partitioned among the three outgoing electrons, which are then most probably emitted with an equilateral triangle configuration. Our results agree well with experiments as compared with early quantum-mechanical calculation as well as classical simulation based on a two-dimensional Bohr's model. Furthermore, by mapping the final momentum vectors event by event into a Dalitz plot,we unambiguously demonstrate that the ergodicity has been reached and thus confirm a long-term scenario conceived by Wannier. The time scale for such few-body thermalization, from the initial nonequilibrium state to the final microcanonical distribution, is only about 100 attoseconds. Finally, we predict that, with the increase of the excess energy, the dominant emission configuration undergoes a transition from equilateral triangle to T-shape and finally to a co-linear mode. The associated signatures of such configuration transition in the electron–ion joint momentum spectrum and triple-electron angular distribution are also demonstrated.展开更多
Classical molecular dynamics simulation has been widely used to study the rapid cooling process of preparing amorphous alloys.However,the simulated cooling rate is several orders of magnitude higher than the experimen...Classical molecular dynamics simulation has been widely used to study the rapid cooling process of preparing amorphous alloys.However,the simulated cooling rate is several orders of magnitude higher than the experimental cooling rate.In this paper,Zr_(55)Cu_(35)Al_(10)alloy was taken as an example.It is found that adding isothermal annealing at a temperature slightly lower than Tand prolonging isothermal annealing time could effectively reduce the cooling rate.The glassy sample prepared in this way demonstrates significant energetic stability and well-developed short-range and medium-range order.展开更多
基金supported by the National Natural Science Foundation of China(12325501 and 12447101).
文摘In the effort to develop useful quantum computers,simulating quantum machines with conventional classical computing resources is a key capability.Such simulations will always face limits,preventing the emulation of quantum computers at substantial scale;however,by pushing the envelope through optimal choices of algorithms and hardware,the value of simulator tools can be maximized.This work reviews state-of-the-art numerical simulation methods,i.e.,classical algorithms that emulate quantum computer evolution under specific operations.We focus on the mainstream state-vector and tensor-network paradigms,while briefly mentioning alternative methods.Moreover,we review the diverse applications of simulation across different facets of quantum computer development,including understanding the fundamental differences between quantum and classical computations,exploring algorithmic design for quantum advantage,predicting quantum processor performance at the design stage,and efficiently characterizing fabricated devices for rapid iterations.This review complements recent surveys of current tools and implementations;here,we aim to provide readers with an essential understanding of the theoretical basis of classical simulation methods,a detailed discussion of their advantages and limitations,and an overview of the demands and challenges arising from practical use cases.
基金supported by the National Key Research and Development Program of China (No. 2021YFF0500600)Natural Science Foundation of Henan Province (No. 242300421129, 252300421176 and 232301420051)National Natural Science Foundation of China (No. 22478361). The computations were performed at National Supercomputing Center in Zhengzhou, China.
文摘The elucidation of the multi-scale transport phenomena of lithium ions in solid electrolyte under working conditions poses huge challenges to both experimental and theoretical realms.Highresolution ab initio molecular dynamics simulations are severely limited by spatial and temporal scales,hindering direct comparisons with experimental observations under room temperature and applied electric potential.Herein,classical molecular dynamics simulations under constant potential are employed to unveil the migration mechanism of Li-ions in Li_(6)PS_(5)Cl(LPSC)confined by electrode interfaces considering realistic conditions.By sophisticated manipulation of anion compositions in LPSC electrolyte,it is observed that neighboring vacancies provide effective pathways for Li-ions migration and the coordination environments evolves progressively with increasing diffusion coefficient,while the conductivity exhibits a non-monotonic peak in Li_(5.3)PS_(4.3)Cl_(1.7).The semiquantitative agreement with existing experimental resultsdemonstrates the superiority of our constant potential solid electrolytemodel,which weexpect to provide atomistic understanding towards rational design of solid electrolyte.
基金support from the Youth Talent Lifting Project(Grant No.2020-JCJQ-QT-030)the National Natural Science Foundation of China(Grant Nos.11905294,and 12274464)+7 种基金the China Postdoctoral Science Foundation,and the Open Research Fund from State Key Laboratory of High Performance Computing of China(Grant No.201901-01)support from the National Natural Science Foundation of China(Grant Nos.11805279,12074117,61833010,and 12061131011)support from the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)the National Natural Science Foundation of China(Grant Nos.61832003,61872334,and 61801459)the National Natural Science Foundation of China(Grant No.12005015)the National Natural Science Foundation of China(Grant Nos.11974205,and 11774197)the National Key Research and Development Program of China(Grant No.2017YFA0303700)the Key Research and Development Program of Guangdong Province(Grant No.2018B030325002).
文摘Quantum computing is a game-changing technology for global academia,research centers and industries including computational science,mathematics,finance,pharmaceutical,materials science,chemistry and cryptography.Although it has seen a major boost in the last decade,we are still a long way from reaching the maturity of a full-fledged quantum computer.That said,we will be in the noisy-intermediate scale quantum(NISQ)era for a long time,working on dozens or even thousands of qubits quantum computing systems.An outstanding challenge,then,is to come up with an application that can reliably carry out a nontrivial task of interest on the near-term quantum devices with non-negligible quantum noise.To address this challenge,several near-term quantum computing techniques,including variational quantum algorithms,error mitigation,quantum circuit compilation and benchmarking protocols,have been proposed to characterize and mitigate errors,and to implement algorithms with a certain resistance to noise,so as to enhance the capabilities of near-term quantum devices and explore the boundaries of their ability to realize useful applications.Besides,the development of near-term quantum devices is inseparable from the efficient classical sim-ulation,which plays a vital role in quantum algorithm design and verification,error-tolerant verification and other applications.This review will provide a thorough introduction of these near-term quantum computing techniques,report on their progress,and finally discuss the future prospect of these techniques,which we hope will motivate researchers to undertake additional studies in this field.
基金supported by the Guangdong Innovative and Entrepreneurial Research Team Program (2016ZT06D348)Natural Science Foundation of Guangdong Province (2017B030308003)+6 种基金the Key R&D Program of Guangdong Province (2018B030326001)the Science, Technology and Innovation Commission of Shenzhen Municipality (JCYJ20170412152620376, JCYJ20170817105046702 and KYTDPT20181011104202253)the National Natural Science Foundation of China (11875160 and U1801661)supported by the National Natural Science Foundation of China (61832003, 61872334)the Economy, Trade and Information Commission of Shenzhen Municipality (201901161512)the Strategic Priority Research Program of Chinese Academy of Sciences (XDB28000000)K. C. Wong Education Foundation
文摘Gaussian boson sampling is an alternative model for demonstrating quantum computational supremacy,where squeezed states are injected into every input mode, instead of applying single photons as in the case of standard boson sampling. Here by analyzing numerically the computational costs, we establish a lower bound for achieving quantum computational supremacy for a class of Gaussian bosonsampling problems. Specifically, we propose a more efficient method for calculating the transition probabilities, leading to a significant reduction of the simulation costs. Particularly, our numerical results indicate that one can simulate up to 18 photons for Gaussian boson sampling at the output subspace on a normal laptop, 20 photons on a commercial workstation with 256 cores, and about 30 photons for supercomputers. These numbers are significantly smaller than those in standard boson sampling, suggesting that Gaussian boson sampling could be experimentally-friendly for demonstrating quantum computational supremacy.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12174034, 12047510, and 11822401)NSAF (Grant Nos. U1930402 and U1930403)。
文摘We study the double ionization dynamics of a helium atom impacted by electrons with full-dimensional classical trajectory Monte Carlo simulation. The excess energy is chosen to cover a wide range of values from 5 e V to 1 ke V for comparative study. At the lowest excess energy, i.e., close to the double-ionization threshold, it is found that the projectile momentum is totally transferred to the recoil-ion while the residual energy is randomly partitioned among the three outgoing electrons, which are then most probably emitted with an equilateral triangle configuration. Our results agree well with experiments as compared with early quantum-mechanical calculation as well as classical simulation based on a two-dimensional Bohr's model. Furthermore, by mapping the final momentum vectors event by event into a Dalitz plot,we unambiguously demonstrate that the ergodicity has been reached and thus confirm a long-term scenario conceived by Wannier. The time scale for such few-body thermalization, from the initial nonequilibrium state to the final microcanonical distribution, is only about 100 attoseconds. Finally, we predict that, with the increase of the excess energy, the dominant emission configuration undergoes a transition from equilateral triangle to T-shape and finally to a co-linear mode. The associated signatures of such configuration transition in the electron–ion joint momentum spectrum and triple-electron angular distribution are also demonstrated.
文摘Classical molecular dynamics simulation has been widely used to study the rapid cooling process of preparing amorphous alloys.However,the simulated cooling rate is several orders of magnitude higher than the experimental cooling rate.In this paper,Zr_(55)Cu_(35)Al_(10)alloy was taken as an example.It is found that adding isothermal annealing at a temperature slightly lower than Tand prolonging isothermal annealing time could effectively reduce the cooling rate.The glassy sample prepared in this way demonstrates significant energetic stability and well-developed short-range and medium-range order.
