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Solving the subset sum problem by the quantum Ising model with variational quantum optimization based on conditional values at risk

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Science China(physics,Mechanics & Astronomy) 2024年第8期67卷 43-55页

作者： Qilin Zheng Miaomiao Yu Pingyu Zhu Yan Wang Weihong Luo Ping Xu institute for Quantum Information and State Key Laboratory of High Performance Computing College of Computer Science and TechnologyNational University of Defense TechnologyChangsha 410073China Hefei National Laboratory Hefei 230088China

The subset sum problem is a combinatorial optimization problem,and its complexity belongs to the nondeterministic polynomial time complete(NP-Complete)*** problem is widely used in encryption,planning or scheduling,and integer *** accurate search algorithm with polynomial time complexity has not been found,which makes it challenging to be solved on classical *** effectively solve this problem,we translate it into the quantum Ising model and solve it with a variational quantum optimization method based on conditional values at *** proposed model needs only n qubits to encode 2ndimensional search space,which can effectively save the encoding quantum *** model inherits the advantages of variational quantum algorithms and can obtain good performance at shallow circuit depths while being robust to noise,and it is convenient to be deployed in the Noisy Intermediate Scale Quantum *** investigate the effects of the scalability,the variational ansatz type,the variational depth,and noise on the ***,we also discuss the performance of the model under different conditional values at *** computer simulation,the scale can reach more than nine *** selecting the noise type,we construct simulators with different QVs and study the performance of the model with *** addition,we deploy the model on a superconducting quantum computer of the Origin Quantum Technology Company and successfully solve the subset sum *** model provides a new perspective for solving the subset sum problem.

关键词： subset sum problem quantum Ising model conditional values at risk variational quantum optimization

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Ignition of neutrino-dominated accretion disks

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Science China(physics,Mechanics & Astronomy) 2012年第2期55卷 316-319页

作者： LIU Tong XUE Li Department of physics and institute of Theoretical physics and Astrophysics Xiamen UniversityXiamen 361005China

The vertical structure of neutrino-dominated accretion flows （NDAFs） in spherical coordinates is revisited. We define the ratio of the neutrino cooling rate to the viscous heating rate per unit volume, f=-qJqvis. The ignition region is presented when f〉0.5. The solutions show that NDAF is significantly thick. The ignition region is determined by the mass accretion rate and the vis- cosity parameter, which can be considered as the neutrino radiation-dominated region.

关键词： accretion accretion disks-black hole physics-gamma rays: bursts

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ABSOLUTE MEASUREMENT OF PHOTOIONIZATION CROSS-SECTIONS OF EXCITED STATES 3s5s^(1)S AND 3s4d^(1)D IN MAGNESIUM

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Chinese physics Letters 1989年第2期6卷 60-63页

作者： HOU Meiying ZHANG Zuren LI Jiaming LIU Lei NING Xjjing institute of physics Academy of SciencesBeijing Department of physics Weinan Normal CollegeShanxi

We report the first experimental investigation of the photoionization cross-sec-tions of singlet excited ststes 3s5s^(1)S and 3s4d^(1)D in atomic magnesium,which can not be directly reached from the ground *** measured absolute values areσ3s5s^(1)S(571.1nm)=(0.27±0.09)Mb andσ3s4d^(1)D(552.8nm)=(2.6±0.9)*** calculations were given,which are in good agreement with the measured values.

关键词： (1) magnesium absolute

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Evolution of a Cold Non-neutral Electron-Positron Plasma Slab

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Chinese physics Letters 2016年第8期33卷 81-84页

作者：汪友梅郁明阳 L.Stenflo A.R.Karimov Department of physics School of ScienceHangzhou Dianzi University institute for Fusion Theory and Simulation Department of PhysicsZhejiang University institute for Theoretical physics I Ruhr University Department of physics Linkoping University institute for High Temperatures Russian Academy of Sciences Department of Electrophysical Facilities National Research Nuclear University MEPhI

Evolution of a non-neutral cold electron-positron plasma slab is investigated. Initially the slab consists of a quasineutral plasma core bounded on both sides by layers containing only positrons （or electrons）. Results from a nonperturbative, or mathematically exact, analysis of the governing fluid conservation equations and the Poisson equation show that despite their equal mass and charge magnitude, the electron and positron fronts can expand separately as well as a single fluid, and that nonlinear surface oscillations can be excited on the expansion fronts.

关键词： of on as it or Evolution of a Cold Non-neutral Electron-Positron Plasma Slab that

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A Reflected Terahertz-Emission Microscopy

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Chinese physics Letters 2007年第1期24卷 169-171页

作者：杨玉平严伟汪力 Academy of physics and Electronic Engineering Central University for Nationalities Beijing 100081 Laboratory of Optical physics Institute of Physics and' Center for Condensed Matter Physics Chinese Academy of Sciences Beijing 100080

A novel reflected terahertz-emission microscopy is proposed and developed for improving the spatial resolution of THz imaging. When attaching a bow-tie antenna directly onto a thin generation crystal, the reflected THz waves can be collected and detected by a photoconductive antenna, and the spatial resolution is decided by the diameter of focused pump beam. In this way, the detected resolution can be largely improved and tunable. The configuration and characteristics of this microscopy are described in detail.

关键词： MICROSCOPY ANTENNAS (Electronics) PHOTOCONDUCTIVITY ELECTRON beams

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High-precision group-delay dispersion measurements of optical fibers via fingerprint-spectral wavelength-to-time mapping

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Photonics Research 2016年第1期4卷 13-16页

作者： Takashi Ito Ondrej Slezak Masahiro Yoshita Hidefumi Akiyama Yohei Kobayashi Institue for Solid State physics University of Tokyo HiLASE Centre Institute of Physics ASCR

The group-delay dispersion of an optical fiber was measured with the time-of-flight method, using fingerprint-like characteristic spectra from a mode-locked fiber laser source. To determine the group-delay dispersion up to the fourth order, least-squares fitting was applied to the overall time waveform mapped on the time axis for the fingerprint-spectral broadband pulses through a long optical fiber. The analysis of all 4003 data points reduced statistical uncertainty, and provided second-, third-, and fourth-order dispersion with uncertainties of 0.02%, 0.4%, and 4%,respectively.

关键词： length time High-precision group-delay dispersion measurements of optical fibers via fingerprint-spectral wavelength-to-time mapping

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About detecting CP-violating processes in J/ψ→K～0K～0 decay

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Chinese physics C 2009年第2期33卷 85-88页

作者：李海波杨茂志 institute of High Energy physics Chinese Academy of Sciences Department of physics Nankai University

Abstract Questions about detecting the CP-violating decay process of J/ψ→ K^0K^-0→ KsKs are discussed. Possible background and material regeneration effects are analyzed. The discussion can be directly extended to ... 详细信息

关键词： CP-violation quarkonium regeneration J/ψ decay BES

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A two-field-scan harmonic Hall voltage analysis for fast,accurate quantification of spin-orbit torques in magnetic heterostructures

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Science China(physics,Mechanics & Astronomy) 2024年第10期67卷 105-112页

作者： Xin Lin Lijun Zhu State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049China

We report on the development of a“two-field-scan”harmonic Hall voltage(HHV)analysis,which collects the second HHVas a function of a swept in-plane magnetic field at 45°and 0°relative to the excitation current,for the determination of the spin-orbit torques of transverse spins in magnetic heterostructures without significant perpendicular spins,longitudinal spins,and longitudinal/perpendicular Oersted *** demonstrate that this two-field-scan analysis is as accurate as the well-established but time-consuming angle-scan HHV analysis even in the presence of considerable thermoelectric effects but takes more than a factor of 7 less measurement *** also show that the fit of the HHV data from a single field scan at 0°,which is commonly employed in the literature,is not reliable because the employment of too many free parameters in the fitting of the very slowly varying HHV signal allows erroneous conclusion about the spin-orbit torque efficiencies.

关键词： spin-orbit torque spin current spin-orbit coupling spintronics

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Spot size measurement of a flash-radiography source using the pinhole imaging method

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Chinese physics C 2016年第7期40卷 124-128页

作者：王毅李勤陈楠程晋明谢宇彤刘云龙龙全红 Key Laboratory of Pulsed Power Institute of Fluid Physics China Academy of Engineering Physics

The spot size of the X-ray source is a key parameter of a flash-radiography facility, and is usually quoted as an evaluation of the resolving power. The pinhole imaging technique is applied to measure the spot size of the Dragon-I linear induction accelerator, by which a two-dimensional spatial distribution of the source spot is obtained. Experimental measurements are performed to measure the spot image when the transportation and focusing of the electron beam are tuned by adjusting the currents of solenoids in the downstream section. The spot size of full-width at half maximum and that defined from the spatial frequency at half peak value of the modulation transfer function are calculated and discussed.

关键词： spot size X-ray source pinhole linear induction accelerator

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Eccentricity and elliptic flow at a fixed centrality in Au+Au collisions at (sNN)^(1/2)=200 GeV in an AMPT model

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Chinese physics C 2013年第1期37卷 58-61页

作者：王美娟陈刚吴元芳 physics Department China University of Geoscience institute of Particle physics Huazhong Normal University

In this paper, elliptic flow is studied at fixed centrality in Au＋Au collision at √sNN=200 GeV in the AMPT model. It is observed that with the participant increasing, elliptic flow has an increase or a decrease at different fixed impact parameter, but it does not have a trivial fluctuation. It is analyzed that the initial space anisotropy dominates the participant dependence of elliptic flow in near-central collisions（b=5 fm） and mid-central collisions（b=8 fm）, while the interaction between particles can mainly answer for the behavior of elliptic flow with participant in peripheral collisions （b=12 fm）. To distinguish the pure geometrical effect, elliptic flow scaled by initial eccentricity is studied. It is found that the ratio v2/ε increases with participant and reaches a saturation when the participant is large enough, indicating that the collision system may reach the local equilibrium.

关键词： elliptic flow initial eccentricity at a fixed centrality local equilibrium

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