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Development of 400-μW cryogen-free dilution refrigerators for quantum experiments
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作者 关翔 樊洁 +2 位作者 边勇波 程智刚 姬忠庆 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期28-35,共8页
We have successfully developed cryogen-free dilution refrigerators with medium cooling power that can be applied to quantum experiments. Breakthroughs have been made in some key technologies and components of heat swi... We have successfully developed cryogen-free dilution refrigerators with medium cooling power that can be applied to quantum experiments. Breakthroughs have been made in some key technologies and components of heat switches and dilution units. Our prototype has been running continuously and stably for more than 100 hours below 10 m K, with a minimum temperature of 7.6 m K and a cooling power of 450 μW at 100 m K. At the same time, we have also made progress in the application of dilution refrigerators, such as quantum computing, low-temperature detector, and magnet integration. These indicators and test results indicate good prospects for application in physics, astronomy, and quantum information. 展开更多
关键词 cryogen-free dilution refrigerator quantum computing low-temperature detector superconducting magnet
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Shot noise of the spin inelastic tunneling through a quantum dot with single molecule-magnet
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作者 常博 梁九卿 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第1期601-608,共8页
We have studied the quantum fluctuations of inelastic spin-electron scattering in quantum dot with an embedded biaxial single molecule-magnet and particularly investigated the zero-frequency shot noise and Fano factor... We have studied the quantum fluctuations of inelastic spin-electron scattering in quantum dot with an embedded biaxial single molecule-magnet and particularly investigated the zero-frequency shot noise and Fano factor in different magnetic fields. It is found that the shot noise and Fano factor exhibit a stepwise behaviour as bias increases in the presence of interaction between the electron and molecule-magnet for a weak magnetic field. As magnetic field becomes strong, a dip is displayed in the shot-noise-bias curve due to the suppression of inelastic shot noise caused by the quantum tunneling of magnetisation. Because of the spontaneous inelastic tunneling at zero bias, a small shot noise occurs, which results in the case of Fano factor F ≥ 1. Moreover, our results show that the sweeping speed can also influence the shot noise and Fano factor obviously. 展开更多
关键词 quantum dot shot noise molecular magnet quantum tunneling of spin
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Field-tuned quantum effects in a triangular-lattice Ising magnet 被引量:1
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作者 Yayuan Qin Yao Shen +19 位作者 Changle Liu Hongliang Wo Yonghao Gao Yu Feng Xiaowen Zhang Gaofeng Ding Yiqing Gu Qisi Wang Shoudong Shen Helen C.Walker Robert Bewley Jianhui Xu Martin Boehm Paul Steffens Seiko Ohira-Kawamura Naoki Murai Astrid Schneidewind Xin Tong Gang Chen Jun Zhao 《Science Bulletin》 SCIE EI CSCD 2022年第1期38-44,M0003,共8页
We report thermodynamic and neutron scattering measurements of the triangular-lattice quantum Ising magnet TmMgGaO_(4)in longitudinal magnetic fields.Our experiments reveal a quasi-plateau state induced by quantum flu... We report thermodynamic and neutron scattering measurements of the triangular-lattice quantum Ising magnet TmMgGaO_(4)in longitudinal magnetic fields.Our experiments reveal a quasi-plateau state induced by quantum fluctuations.This state exhibits an unconventional non-monotonic field and temperature dependence of the magnetic order and excitation gap.In the high field regime where the quantum fluctuations are largely suppressed,we observed a disordered state with coherent magnon-like excitations despite the suppression of the spin excitation intensity.Through detailed semi-classical calculations,we are able to understand these behaviors quantitatively from the subtle competition between quantum fluctuations and frustrated Ising interactions. 展开更多
关键词 Neutron scattering quantum magnet magnetic frustration Transverse field Ising model
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Shape and magnetic moment dependence of the dipolar field in Mn_(12)-acetate
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作者 ZHOU YuRong LI YanRong +2 位作者 ZUO JunWei LIU RuiYuan WANG YunPing 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2010年第8期1568-1570,共3页
There is a small fraction of fast-relaxation species in Mn12-acetate, which is utilized to determine the dipolar field of Mn12. Here we report an easier way to precisely obtain the dipolar field by measuring the M-H c... There is a small fraction of fast-relaxation species in Mn12-acetate, which is utilized to determine the dipolar field of Mn12. Here we report an easier way to precisely obtain the dipolar field by measuring the M-H curves above the blocking temperature of fastrelaxation species. We found that there is a simple linear relationship between the magnetic moment and dipolar field; besides the dipolar field is also dependent on the sample shape, which is consistent with the numerical calculation. 展开更多
关键词 molecular magnet quantum tunneling dipolar field magnetic relaxation
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New quantum tunneling steps in Mn_(11)Cr/Mn_(12) mixed crystal
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作者 ZHOU YuRong1,LI YanRong1,FAN ZhenJun2 & WANG YunPing1 1Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China 2School of Materials Sciences and Technology,China University of Geosciences,Beijing 430074,China 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2010年第9期1769-1771,共3页
Magnetic properties of Mn11Cr and Mn12 mixed crystal at low temperature are studied.A new set of quantum tunneling steps discovered in magnetization curves suggests that there may exist another kind of single molecula... Magnetic properties of Mn11Cr and Mn12 mixed crystal at low temperature are studied.A new set of quantum tunneling steps discovered in magnetization curves suggests that there may exist another kind of single molecular magnet in this mixed crystal. 展开更多
关键词 quantum TUNNELING molecular magnet magnetIZATION CURVE
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稀土元素三角格子体系中的阻挫磁性与量子涨落 被引量:1
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作者 秦亚媛 沈瑶 +1 位作者 陈钢 赵俊 《物理》 CAS 北大核心 2021年第7期454-462,共9页
稀土元素三角格子阻挫体系在近几年受到了广泛的关注,稀土元素中存在较强的自旋轨道耦合作用,容易形成各向异性的磁相互作用,结合复杂的晶体场结构,可以产生很多新奇的物理性质,实现包括量子自旋液体、内禀量子伊辛磁体和隐藏序在内的... 稀土元素三角格子阻挫体系在近几年受到了广泛的关注,稀土元素中存在较强的自旋轨道耦合作用,容易形成各向异性的磁相互作用,结合复杂的晶体场结构,可以产生很多新奇的物理性质,实现包括量子自旋液体、内禀量子伊辛磁体和隐藏序在内的一系列新奇量子态。文章以最近的中子散射研究为例,介绍稀土元素三角格子体系中的新奇磁关联与量子涨落现象。 展开更多
关键词 量子磁体 磁性阻挫 自旋液体 横场伊辛模型 中子散射 隐藏序
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Deterministic Generation of Quantum State Transfer Between Spatially Separated Single Molecule Magnets
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作者 宋佩君 吕新友 +2 位作者 黄培 郝向英 杨晓雪 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第8期278-286,共9页
We propose a new scheme for realizing deterministic quantum state transfer (QST) between two spatially separated single molecule magnets (SMMs) with the framework of cavity quantum eleetrodynamics (QED). In the ... We propose a new scheme for realizing deterministic quantum state transfer (QST) between two spatially separated single molecule magnets (SMMs) with the framework of cavity quantum eleetrodynamics (QED). In the present scheme, two SMMs are trapped in two spatially separated optical cavities coupled by an optical fiber. Through strictly numerically simulating, we demonstrate that our scheme is robust with respect to the SMMs' spontaneous decay and fiber loss under the conditions of dispersive SMMs-field interaction and strong coupling of cavity fiber. In addition, we also discuss the influence of photon leakage out of cavities and show that our proposal is good enough to demonstrate the generation of QST with high fidelity utilizing the current experimental technology. The present investigation provides research opportunities for realizing QST between solid-state qubits and may result in a substantial impact on the progress of solid-state-based quantum communications network. 展开更多
关键词 quantum state transfer cavity QED single molecule magnet
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基于改进天牛须搜索算法的自抗扰永磁同步电机控制
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作者 刘亚奇 《机械设计与制造工程》 2023年第11期21-26,共6页
针对自抗扰控制器参数多、整定困难的问题,基于改进天牛须搜索算法设计了一种在线自整定参数的自抗扰控制器。针对天牛须搜索算法当前迭代的最优候选解,认为是正、伪两种状态的量子位线性叠加,可用实数编码的量子重新表示,然后利用量子... 针对自抗扰控制器参数多、整定困难的问题,基于改进天牛须搜索算法设计了一种在线自整定参数的自抗扰控制器。针对天牛须搜索算法当前迭代的最优候选解,认为是正、伪两种状态的量子位线性叠加,可用实数编码的量子重新表示,然后利用量子旋转门更新量子表达式。以永磁同步电机作为被控对象进行仿真验证,结果表明基于混合算法的自抗扰控制器有着更好的控制精度和抗扰动性能。 展开更多
关键词 量子进化算法 自抗扰控制器 天牛须搜索算法 永磁同步电机
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笼目晶体中探索未知量子态
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作者 殷嘉鑫 《物理》 CAS 北大核心 2023年第3期157-165,共9页
笼目起源于古老中华民俗文化。近期学者们对具有笼目晶格的一系列拓扑材料的研究揭示了量子层次上几何、拓扑、自旋和关联的交缠相互作用,以及随之涌现的丰富多彩的量子现象。文章简要介绍了笼目晶格的相关理论概念、陈数和外尔磁性、... 笼目起源于古老中华民俗文化。近期学者们对具有笼目晶格的一系列拓扑材料的研究揭示了量子层次上几何、拓扑、自旋和关联的交缠相互作用,以及随之涌现的丰富多彩的量子现象。文章简要介绍了笼目晶格的相关理论概念、陈数和外尔磁性、平带关联现象,以及非常规电荷序和超导电性中的谜团。当前,国际上诸多研究机构使用各式手段对笼目磁体和超导体的研究盛况犹如正在举行一场笼目量子派对。然而,这些初步研究还无法突破超导和量子霍尔两大类宏观量子现象。希望此文能激励更多年轻学者在笼目晶体丰富的演生现象中进一步探寻第三类宏观量子现象,迎来真正的量子盛宴。 展开更多
关键词 第三类宏观量子态 笼目材料 笼目磁体 笼目超导
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量子遗传算法在永磁同步轮毂电机优化设计中的应用 被引量:4
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作者 张羽 邓兆祥 +2 位作者 张河山 陶胜超 唐蓓 《重庆大学学报(自然科学版)》 EI CAS CSCD 北大核心 2017年第8期1-8,共8页
量子遗传算法具有种群规模小而不影响算法性能、收敛速度快和全局搜索能力强等优点。为了获得高功率密度和低成本的电动车用轮毂电机,基于量子遗传算法,针对研究设计的一种外转子永磁同步轮毂电机,以电机有效质量、材料成本和功率损耗... 量子遗传算法具有种群规模小而不影响算法性能、收敛速度快和全局搜索能力强等优点。为了获得高功率密度和低成本的电动车用轮毂电机,基于量子遗传算法,针对研究设计的一种外转子永磁同步轮毂电机,以电机有效质量、材料成本和功率损耗为优化目标,建立了包含8个设计变量和5个约束的数学模型,对电机进行优化设计。研究结果表明:永磁同步轮毂电机有效质量、材料成本和功率损耗降低,效率特性提升,有限元分析结果与量子遗传算法计算结果接近,能满足电动车对驱动轮毂电机的使用要求,因此,量子遗传算法对于轮毂电机优化设计是有效可行的。 展开更多
关键词 量子遗传算法 永磁同步轮毂电机 优化设计
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A new manganese-based single-molecule magnet with a record-high antiferromagnetic phase transition temperature
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作者 崔岩 李艳荣 +1 位作者 李瑞元 王云平 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第6期534-537,共4页
We perform both dc and ac magnetic measurements on the single crystal of Mn30(Et-sao)3(C104)(MeOH)3 single- molecule magnet (SMM) when the sample is preserved in air for different durations. We find that, duri... We perform both dc and ac magnetic measurements on the single crystal of Mn30(Et-sao)3(C104)(MeOH)3 single- molecule magnet (SMM) when the sample is preserved in air for different durations. We find that, during the oxidation process, the sample develops into another SMM with a smaller anisotropy energy barrier and a stronger antiferromagnetic intermolecular exchange interaction. The antiferromagnetic transition temperature observed at 6.65 K in the new SMM is record-high for the antiferromagnetic phase transition in all the known SMMs. Compared to the original SMM, the only apparent change for the new SMM is that each molecule has lost three methyl groups as revealed by four-circle x-ray diffraction (XRD), which is thought to be the origin of the stronger antiferromagnetic intermolecular exchange interaction. 展开更多
关键词 single-molecule magnet quantum tunneling of magnetization antiferromagnetic intermolecular exchange interaction
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Resonant tunnelling of the magnetization in molecular crystal of [(Mn1-xCrx)12O12 (CH3COO)16(H2O)4]·2CH3COOH·4H2O(x=0,0.03,0.04,0.05)
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作者 何光 何伦华 +4 位作者 张俊荣 曹慧波 阎丽琴 王芳卫 严启伟 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第6期1776-1779,共4页
The quantum tunnelling of magnetization (QTM) in single crystals of the single molecule magnet (Mn1-xCrx)12- Ac (x=0, 0.03, 0.04, 0.05) has been investigated. In comparison with its parent Mnl2-Ac, a greater rat... The quantum tunnelling of magnetization (QTM) in single crystals of the single molecule magnet (Mn1-xCrx)12- Ac (x=0, 0.03, 0.04, 0.05) has been investigated. In comparison with its parent Mnl2-Ac, a greater rate of magnetization relaxation and a lower effective potential-energy barrier have been observed in Cr-doping samples. This modulation of QTM due to the Cr-doping could be attributed to the small change of Sz due to the smaller spin of Cr itself and additional intrinsic but distributed transverse and longitudinal anisotropy raised by a subtle change of the local environment in the magnetic Mn12 core. 展开更多
关键词 quantum tunnelling of magnetization magnetization relaxation single molecule magnet
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Dephasing of quantum tunnelling in molecular nanomagnets
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作者 张树群 陈芝得 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第4期1436-1442,共7页
Dephasing mechanism of quantum tunnelling in molecular magnets has been studied by means of the spin-coherentstate path integral in a mean field approximation. It is found that the fluctuating uncompensated transverse... Dephasing mechanism of quantum tunnelling in molecular magnets has been studied by means of the spin-coherentstate path integral in a mean field approximation. It is found that the fluctuating uncompensated transverse field from the dipolar-dipolar interaction between molecular magnets contributes a random phase to the quantum interference phase. The resulting transition rate is determined by the average tunnel splitting over the random phase. Such a dephasing process leads to the suppression of quenching due to the quantum phase interference, and to the steps due to odd resonances in hysteresis loop survived, which is in good agreement with experimental observations in molecular nanomagnets Fes and Mn12. 展开更多
关键词 single molecule magnet quantum tunnelling DEPHASING
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Quantum oscillation measurements in high magnetic field and ultra-low temperature
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作者 Pu Wang Gang Li Jian-Lin Luo 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第7期86-90,共5页
The physical properties of a solid are determined by the electrons near the Fermi energy and their low-lying excitations. Thus, it is crucially important to obtain the band structure near the Fermi energy of a materia... The physical properties of a solid are determined by the electrons near the Fermi energy and their low-lying excitations. Thus, it is crucially important to obtain the band structure near the Fermi energy of a material to understand many novel phenomena that occur, such as high-To superconductivity, density waves, and Dirac-type excitations. One important way to determine the Fermi surface topology of a material is from its quantum oscillations in an external magnetic field. In this article, we provide a brief introduction to the substation at the Synergetic Extreme Condition User Facility (SECUF), with a focus on quantum oscillation measurements, including our motivation, the structure of and the challenges in building the substation, and perspectives. 展开更多
关键词 quantum oscillation measurements Fermi surface superconducting magnet
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强关联量子杂质体系的精确模拟 被引量:1
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作者 郑晓 《科学通报》 EI CAS CSCD 北大核心 2018年第33期3412-3418,共7页
对复杂凝聚态体系中的局域量子态的精确描述,以及对量子态在外场、环境调控下的响应与演化机制的深刻理解,对量子功能材料与器件的构筑与设计有着重要的基础性意义.然而,如何精确刻画复杂材料体系中的量子相干、关联、纠缠等特性,对理... 对复杂凝聚态体系中的局域量子态的精确描述,以及对量子态在外场、环境调控下的响应与演化机制的深刻理解,对量子功能材料与器件的构筑与设计有着重要的基础性意义.然而,如何精确刻画复杂材料体系中的量子相干、关联、纠缠等特性,对理论研究而言是个传统难题.本文从全新的视角,即"开放量子体系"的角度来研究复杂凝聚态体系中的量子态.简要介绍了近年来我们基于严格的量子耗散理论发展得到的级联运动方程方法,以及该方法在实验高度关注的强关联量子杂质体系的计算模拟研究方面的应用. 展开更多
关键词 强关联体系 开放量子体系 级联运动方程 近藤效应 分子磁体
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量子霍尔电阻的精密测量 被引量:1
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作者 叶妙元 刘敬香 +1 位作者 李兵 何业冶 《华中理工大学学报》 CSCD 北大核心 1991年第2期133-136,共4页
1980年冯·克里青教授利用MOSEFT在低温强磁场中发现量子霍尔效应,其量子霍尔电阻(QHR)为:R_H=h/(ne^2),(1)式中,e为电子电荷;h为普朗克常数;n为整数.上式表明,量子霍尔电阻只与基本物理常数h/e^2有关,与材质和样品的几何尺寸无关.... 1980年冯·克里青教授利用MOSEFT在低温强磁场中发现量子霍尔效应,其量子霍尔电阻(QHR)为:R_H=h/(ne^2),(1)式中,e为电子电荷;h为普朗克常数;n为整数.上式表明,量子霍尔电阻只与基本物理常数h/e^2有关,与材质和样品的几何尺寸无关.因此,可利用它来建立电阻的自然基准和测量精细结构常数.为了用它建立电阻自然基准,许多国家的实验室都进行了量子霍尔电阻的精密测量,最高测量不确定度已达1×10^(-8).1988年第18届国际计量大会(CGPM)及第77届国际计量委员会(CIPM)作出决议:“自1990年1月1日起,国际上将同时正式启用以约瑟夫逊常数和冯·克里青常数的国际公认值为基础的电学计量新基准复现电压单位和电阻单位. 展开更多
关键词 量子霍尔电阻 精密测量 超导磁体
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基于量子遗传算法的电机优化相关策略及参数选择 被引量:1
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作者 吴凇 陈钢 《鱼雷技术》 2015年第2期113-118,共6页
使用量子遗传算法对电机结构进行优化设计时需要对相关策略和参数进行妥善设置,这对使用者的使用经验有一定要求。以某外转子磁系统永磁无刷双转电机为原型,讨论了旋转角调整策略及收敛判据的选择方法,分析了不同量子交叉、量子变异概... 使用量子遗传算法对电机结构进行优化设计时需要对相关策略和参数进行妥善设置,这对使用者的使用经验有一定要求。以某外转子磁系统永磁无刷双转电机为原型,讨论了旋转角调整策略及收敛判据的选择方法,分析了不同量子交叉、量子变异概率对寻优效果的影响,并介绍了种群规模、优化变量个数的设置思路。归纳总结出使用量子遗传算法解决电机结构优化问题的算法设置方案,可作为解决其他同类问题的参考。 展开更多
关键词 量子遗传算法 电机优化 永磁无刷双转电机
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