检索结果-内蒙古大学图书馆

An Efficient Quantum Circuit for Block Encoding a Pairing Hamiltonian

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Liu, Diyi Du, Weijie Lin, Lin Vary, James P. Yang, Chao Department of Mathematics University of Minnesota Twin CitiesMN United States Department of Physics Iowa State University of Minnesota AmesIA United States Department of Mathematics University of California BerkeleyCA United States Applied Mathematics and Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA United States

We present an efficient quantum circuit for block encoding pairing Hamiltonians often studied in nuclear physics. Our block encoding scheme does not require mapping the creation and annihilation operators to the Pauli operators and representing the Hamiltonian as a linear combination of unitaries. Instead, we show how to encode the Hamiltonian directly using controlled swap operations. We analyze the gate complexity of the block encoding circuit and show that it scales polynomially with respect to the number of qubits required to represent a quantum state associated with the pairing Hamiltonian. We also show how the block encoding circuit can be combined with the quantum singular value transformation to construct an efficient quantum circuit for approximating the density of states of a pairing Hamiltonian. The techniques presented can be extended to encode more general second-quantized *** Codes 68Q12, 81P68 © 2024, CC BY.

关键词： Hamiltonians

Test of electric charge conservation in dark matter direct detection experiment

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Zhang, Z.H. Geng, X.P. Hu, J.W. Zhang, Z.H. Beijing Normal University at Zhuhai Zhuhai519087 China Institute of Applied Physics and Computational Mathematics Beijing100094 China Beijing Honest Technology Co. Ltd Beijing100083 China China Nuclear Power Technology Research Institute Co. Ltd Shenzhen518000 China

Electric charge conservation (ECC) is typically taken as an axiom in the standard model. Searching for small violations with high-performance experiments could lead us to new physics. In this work, we tested "invisible" electric charge nonconservation (ECNC) events with 1.16 ton·year electron recoil data from the XENON-nT experiment. There was no statistically significant signal, and the ECNC limit was updated to τ(e− → νe + ν¯e + νe) > 4.34 × 1027 yr. This work increases the limit by two orders of magnitude and shows that dark matter direct detection experiments have great potential for further ECC testing. Copyright © 2025, The Authors. All rights reserved.

关键词： Dark Matter

Efficient Measurement-Driven Eigenenergy Estimation with Classical Shadows

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Shen, Yizhi Buzali, Alex Hu, Hong-Ye Klymko, Katherine Camps, Daan Yelin, Susanne F. Van Beeumen, Roel Applied Mathematics and Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Physics Harvard University 17 Oxford Street CambridgeMA02138 United States NERSC Lawrence Berkeley National Laboratory BerkeleyCA94720 United States

Quantum algorithms exploiting real-time evolution under a target Hamiltonian have demonstrated remarkable efficiency in extracting key spectral information. However, the broader potential of these methods, particularly beyond ground state calculations, is underexplored. In this work, we introduce the framework of multi-observable dynamic mode decomposition (MODMD), which combines the observable dynamic mode decomposition, a measurement-driven eigensolver tailored for near-term implementation, with classical shadow tomography. MODMD leverages random scrambling in the classical shadow technique to construct, with exponentially reduced resource requirements, a signal subspace that encodes rich spectral information. Notably, we replace typical Hadamard-test circuits with a protocol designed to predict low-rank observables, thus marking a new application of classical shadow tomography for predicting many low-rank observables. We establish theoretical guarantees on the spectral approximation from MODMD, taking into account distinct sources of error. In the ideal case, we prove that the spectral error scales as exp(−∆Etmax), where ∆E is the Hamiltonian spectral gap and tmax is the maximal simulation time. This analysis provides a rigorous justification of the rapid convergence observed across simulations. To demonstrate the utility of our framework, we consider its application to fundamental tasks, such as determining the low-lying, i.e., ground or excited, energies of representative many-body systems. Our work paves the path for efficient designs of measurement-driven algorithms on near-term and early fault-tolerant quantum devices. Copyright © 2024, The Authors. All rights reserved.

关键词： Hamiltonians

Numerical Investigation of an Active Jet Control Method for Hypersonic Inlet Restart

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2022年第6期39卷 651-662页

作者： JIN Yichao YAO Wei Institute of Applied Physics and Computational Mathematics Beijing 100094P.R.China Key Laboratory of High-Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190P.R.China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049P.R.China

A flow control method based on an active jet is developed to restart hypersonic inlets. The dynamic restarting process is numerically reproduced by unsteady Reynolds averaged Navier-Stokes(RANS) modeling to verify the effectiveness and reveal the influence of jet conditions. The active jet improves the inlet unstart status by drawing the high-pressure separation bubble from the internal compression duct and performing a full expansion to alleviate the adverse pressure gradient. Moreover, the favorable pressure gradient in the inlet caused by jet expansion allows for a successful restart after turning off the jet. The influence of the jet momentum ratio is then analyzed to guide the design of the active jet control method and choose the proper momentum ratios. A low jet momentum does not eliminate the high-pressure separation bubble, whereas an excessive jet momentum causes severe momentum loss due to the induced shock. The general rule in restarting the inlet using an active jet is to allow a full jet expansion downstream of the jet slot while avoiding excessive momentum loss upstream and preventing the thick low-speed layer.

关键词： hypersonic inlet unstart restart active jet flow control

Dynamical Exciton Condensates in Biased Electron-Hole Bilayers

学校读者我要写书评

暂无评论

Physical Review Letters 2024年第21期133卷 217002-217002页

作者： Zhiyuan Sun Yuta Murakami Fengyuan Xuan Tatsuya Kaneko Denis Golež Andrew J. Millis State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics Tsinghua University Beijing 100084 People’s Republic of China Department of Physics Columbia University 538 West 120th Street New York New York 10027 USA Center for Emergent Matter Science RIKEN Wako Saitama 351-0198 Japan Suzhou Laboratory Suzhou 215123 China Department of Physics Osaka University Toyonaka Osaka 560-0043 Japan Jožef Stefan Institute Jamova 39 SI-1000 Ljubljana Slovenia Faculty of Mathematics and Physics University of Ljubljana Jadranska 19 SI-1000 Ljubljana Slovenia Center for Computational Quantum Physics Flatiron Institute 162 5th Avenue New York New York 10010 USA

Bilayer materials may support interlayer excitons comprised of electrons in one layer and holes in the other. In experiments, a nonzero exciton density is typically sustained by a bias chemical potential, implemented either by optical pumping or by electrical contacts connected to the two layers. We show that if charge can tunnel between the layers, the chemical potential bias means that an exciton condensate is in the dynamical regime of ac Josephson effect. It has physical consequences such as tunneling currents and the ability to tune a condensate from bright (emitting coherent photons) to dark by experimental controlling knobs. If the system is placed in an optical cavity, coupling with cavity photons favors different dynamical states depending on the bias, realizing superradiant phases.

关键词： Cavity quantum electrodynamics Dynamical phase transitions Electroluminescence Excitons Josephson effect Polaritons Superfluidity Floquet systems Nonequilibrium systems Transition metal dichalcogenides Two-dimensional electron system

Molecular dynamics investigation of the stopping power of warm dense hydrogen for electrons

学校读者我要写书评

暂无评论

Physical Review E 2021年第6期103卷 063215-063215页

作者： Yun Liu Xing Liu Shen Zhang Hao Liu Chongjie Mo Zhenguo Fu Jiayu Dai Department of Applied Physics School of Physics and Electronics Hunan University Changsha 410082 China Center for Applied Physics and Technology School of Physics Peking University Beijing 100086 China Department of Physics National University of Defense Technology Changsha 410073 China Beijing Computational Science Research Center Beijing 100193 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China

A variety of theoretical models have been proposed to calculate the stopping power of charged particles in matter, which is a fundamental issue in many fields. However, the approximation adopted in these theories will be challenged under warm dense matter conditions. Molecular dynamics (MD) simulation is a good way to validate the effectiveness of these models. We investigate the stopping power of warm dense hydrogen for electrons with projectile energies ranging from 400–10000 eV by means of an electron force field (eFF) method, which can effectively avoid the Coulomb catastrophe in conventional MD calculations. It is found that the stopping power of warm dense hydrogen decreases with increasing temperature of the sample at those high projectile velocities. This phenomenon could be explained by the effect of electronic structure dominated by bound electrons, which is further explicated by a modified random phase approximation (RPA) model based on local density approximation proper to inhomogeneous media. Most of the models extensively accepted by the plasma community, e.g., Landau-Spitzer model, Brown-Preston-Singleton model and RPA model, cannot well address the effect caused by bound electrons so that their predictions of stopping power contradict our result. Therefore, the eFF simulations of this paper reveals the important role played by the bound electrons on stopping power in warm dense plasmas.

关键词： Fast ignition High-energy-density plasmas Plasma-particle interactions Strongly-coupled plasmas Warm-dense matter Molecular dynamics

Determination of Landé gJ factor and Zeeman coefficients in ground-state 171Yb+ and their applications to quantum frequency standards

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Han, Jize Lu, Benquan Yu, Yanmei Li, Jiguang Huang, Zhiguo Wen, Jingwei Qian, Ling Wang, Lijun State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instrument Tsinghua University Beijing100084 China Software Technology Company Limited Suzhou215163 China National Time Service Center Chinese Academy of Sciences Xi’an710600 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Department of Physics Tsinghua University Beijing100084 China

We report the determination of the Landé gJ factor and Zeeman coefficients for the ground-state of 171Yb+, relevant to microwave quantum frequency standards (QFSs). The gJ factor is obtained by using two independent methods: multiconfiguration Dirac-Hartree-Fock and multireference configuration interaction, yielding a consistent value of 2.002615(70). The first- and second-order Zeeman coefficients are determined as 14,010.78(49) Hz/µT and 31.0869(22) mHz/µT2, respectively, based on the calculated gJ factor. These coefficients enable reduced magnetic-field-induced uncertainties, improving the accuracy of the 171Yb+ microwave QFSs. The results reported in this work also offer potential for improved constraints on variations in fundamental constants through frequency comparisons, and advancing trapped-ion quantum computers based on the ground-state hyperfine splitting of 171Yb+ © 2025, CC BY.

关键词： Trapped ions

The non-perturbative adiabatic invariant is all you need

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Burby, J.W. Maldonado, I.A. Ruth, M. Messenger, D.A. Department of Physics Institute for Fusion Studies The University of Texas at Austin AustinTX78712 United States Department of Physics The University of Texas at Austin AustinTX78712 United States Department of Physics The Oden Institute for Computational Engineering and Sciences The University of Texas at Austin AustinTX78712 United States University of Colorado Department of Applied Mathematics BoulderCO80309-0526 United States

Perturbative guiding center theory adequately describes the slow drift motion of charged particles in the strongly-magnetized regime characteristic of thermal particle populations in various magnetic fusion devices. However, it breaks down for particles with large enough energy. We report on a data-driven method for learning a non-perturbative guiding center model from full-orbit particle simulation data. We show the data-driven model significantly outperforms traditional asymptotic theory in magnetization regimes appropriate for fusion-born α-particles in stellarators, thus opening the door to non-perturbative guiding center calculations. Copyright © 2024, The Authors. All rights reserved.

关键词： Stellarators

Optical potential parameters of light nuclear fusion based on precise Coulomb wave functions

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Wu, Binbing Duan, Hao Liu, Jie Graduate School China Academy of Engineering Physics Beijing100193 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100088 China CAPT HEDPS IFSA Collaborative Innovation Center of MoE Peking University Beijing100871 China

Based on precise Coulomb wave functions (CWFs), we attempt to calculate the fusion cross sections of light nuclei in a complex spherical square-well nuclear potential (i.e., optical potential model). Comparing with experimental benchmark cross section data, we can calibrate optical potential parameters associated with D+D, D+T, D+3He, p+D, p+6Li and p+7Li fusion reactions. Surprisingly, we find that our calculated optical potential parameters are quite different from those of many previous results (e.g., Phys. Rev. C. 61 (2000) 024610, Nucl. Phys. A 986 (2019) 98, etc.), in which approximate Coulomb wave functions (ACWFs) with only retaining the leading terms are exploited for the continuity conditions at the radius of nuclear potential. Furthermore, with the obtained optical potential parameters, we compare the fusion cross sections and astrophysical S-factors with that formulated from ACWFs approach, and also find apparent deviations especially for the fusion reactions with resonance peaks such as D+T and D+3He fusion reactions. We then calculate the phase diagrams of the fusion cross sections with respect to the optical potential parameters and demonstrate several narrow shape resonance belts. It implies that a small deviation of ACWFs from the exact CWFs at nuclear radius might lead to fall off the resonance regimes and therefore causes the big difference on the optical parameters as well as the cross sections. Copyright © 2021, The Authors. All rights reserved.

关键词： Wave functions