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点亮量子优势

物理 2022年第11期51卷 781-783页

作者：金贻荣(编译) 北京量子信息科学研究院

IBM量子部副总裁Jay Gambetta与Philip Ball谈论了该公司过去20年来在量子领域取得的诸多进展,以及最近宣布的“量子优势”五年路线图。当下,全球各地的很多公司和实验室都在致力于将他们最新的量子技术推出实验室,走进现实世界。这其中... 详细信息

IBM量子部副总裁Jay Gambetta与Philip Ball谈论了该公司过去20年来在量子领域取得的诸多进展,以及最近宣布的“量子优势”五年路线图。当下,全球各地的很多公司和实验室都在致力于将他们最新的量子技术推出实验室,走进现实世界。这其中,美国科技巨头IBM是一个非常关键的参与者。就在今年5月,IBM量子公布了他们最新的未来十年量子计算路线(图1),而且,这家公司还设置了一些雄心勃勃的目标。在去年他们推出了包含127个量子比特(qubits)的Eagle处理器之后,该公司正在开发包含433个量子比特的Osprey处理器,并将于今年底首次亮相,随后将于2023年推出包含1121个比特的Condor处理器。

关键词：量子比特 IBM Condor 量子计算量子技术实验室路线图

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D相AlCuCo准晶各向异性热电势的测量

物理学报 2009年第10期58卷 7119-7123页

作者：樊振军耿学文孔文婕金贻荣中国地质大学(北京)材料科学与工程学院北京100083 中国科学院物理研究所北京100190 广西师范大学物理与电子工程学院桂林541004

采用激光交流加热的方法测量了D相AlCuCo准晶周期与准周期两个方向的热电势,温度测量区间为300—1200K.通过测量发现沿周期方向的热电势符号为负,沿准周期方向的热电势符号为正;沿周期方向在1123K(850℃)热电势有一个跳变;在高温区,热... 详细信息

采用激光交流加热的方法测量了D相AlCuCo准晶周期与准周期两个方向的热电势,温度测量区间为300—1200K.通过测量发现沿周期方向的热电势符号为负,沿准周期方向的热电势符号为正;沿周期方向在1123K(850℃)热电势有一个跳变;在高温区,热电势并不是单调变化的;实验所用方法能比较灵敏地测量材料相变时的温度点.

关键词： AlCuCo准晶高温热电势交流测量法

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超导与量子计算

自然杂志 2020年第4期42卷 301-310页

作者：金贻荣北京量子信息科学研究院北京100193

基于量子力学态叠加性和纠缠性的量子计算,以其指数级增长的庞大计算空间和更高级的信息抽象能力,为计算提供了新的范式。这一新技术有可能解决一些经典计算无法解决的计算难题,同时解决经典计算的功耗问题。超导效应作为一种宏观量子效... 详细信息

基于量子力学态叠加性和纠缠性的量子计算,以其指数级增长的庞大计算空间和更高级的信息抽象能力,为计算提供了新的范式。这一新技术有可能解决一些经典计算无法解决的计算难题,同时解决经典计算的功耗问题。超导效应作为一种宏观量子效应,为量子态相干操控提供了绝佳的无损耗环境,而约瑟夫森结为构建量子比特提供了必要的能级分立性和非线性。经过二十余年的高速发展,基于超导量子电路的量子计算技术已经在退相干时间、量子态操控和读取、量子比特间可控耦合、中大规模扩展等关键技术上取得大量突破,成为构建通用量子计算机和量子模拟机最有前途的候选技术路线之一。文章就这一技术做一个简要的介绍和梳理,以令读者了解整个技术脉络为目标,尽可能不涉及复杂的符号和公式。最后,还简要讨论了超导量子计算发展的未来,并指出其中部分关键技术难点。

关键词：量子计算超导量子比特量子电路约瑟夫森结量子模拟

Degradation Mechanism of the Superconducting Transition Temperature in Nb Thin Films

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Chinese Physics Letters 2015年第4期32卷 122-125页

作者：宋小会金贻荣樊振军米振宇张殿琳 Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 School of Sciences China University of Ceosciences Beijing 100083

Systemic measurements show that there is no 3D to 2D crossover in the reduction of the superconducting transition temperature Tc in Nb thin films. This result is consistent with all previous measurements while it is contrary to the prevailing understanding based on the interplay between proximity, localization, and lifetime broadening. Our study indicates that the decrease of Tc can be interpreted by the combined effects of electron-phonon coupling parameter λ and the defect scattering rate pw, being uniquely determined by their ratio λ/ρw. Other factors such as film thickness and irradiation do not produce additional effects beyond these two parameters.

关键词： Degradation Mechanism of the Superconducting Transition Temperature in Nb Thin Films

Fabrication of superconducting NbN meander nanowires by nano-imprint lithography

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Chinese Physics B 2016年第1期25卷 384-389页

作者：杨美刘丽华宁鲁慧金贻荣邓辉李洁李阳郑东宁 Department of Physics School of Mathematics and PhysicsUniversity of Science and Technology BeijingBeijing 100083China Institute of Physics Chinese Academy of SciencesBeijing 1 O0190China

Superconducting nanowire single photon detector （SNSPD）, as a new type of superconducting single photon detector （SPD）, has a broad application prospect in quantum communication and other fields. In order to prepare SNSPD with high performance, it is necessary to fabricate a large area of uniform meander nanowires, which is the core of the SNSPD. In this paper, we demonstrate a process of patterning ultra-thin NbN films into meander-type nanowires by using the nano- imprint technology. In this process, a combination of hot embossing nano-imprint lithography （HE-NIL） and ultraviolet nano-imprint lithography （UV-NIL） is used to transfer the meander nanowire structure from the NIL Si hard mold to the NbN film. We have successfully obtained a NbN nanowire device with uniform line width. The critical temperature （Tc） of the superconducting NbN meander nanowires is about 5 K and the critical current （lc） is about 3.5 μA at 2.5 K.

关键词： nano-imprint lithography meander nanowires ultra-thin NbN films

基于高温超导量子干涉仪的超低场核磁共振成像研究

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物理学报 2012年第21期61卷 196-203页

作者：王宁金贻荣邓辉吴玉林郑国林李绍田野任育峰陈莺飞郑东宁中国科学院物理研究所北京100190

对基于高温超导量子干涉仪的低场核磁共振成像进行了较为系统的探索.首先对低场核磁共振系统进行了改进和完善,使得装置能够用于成像实验.在此基础上进行了一维、二维成像实验并取得了成功.二维成像分别采用了直接背投影成像法和傅里叶... 详细信息

对基于高温超导量子干涉仪的低场核磁共振成像进行了较为系统的探索.首先对低场核磁共振系统进行了改进和完善,使得装置能够用于成像实验.在此基础上进行了一维、二维成像实验并取得了成功.二维成像分别采用了直接背投影成像法和傅里叶变换重建法.采用直接背投影方法成功获得了不同水样品分布的图形并与实物符合较好,同时还尝试对生物样品如青椒和芹菜的切片进行了成像,也得到了符合原物的二维投影像.尝试用傅里叶变换法对水样品进行成像,得到的图形能够显示样品轮廓,但信噪比偏低.对两种二维成像方法进行了比较和讨论.

关键词：超导量子干涉仪超低场核磁共振成像

Study on signal intensity of low field nuclear magnetic resonance via an indirect coupling measurement

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Chinese Physics B 2013年第4期22卷 36-39页

作者：蒋凤英王宁金贻荣邓辉田野郎佩琳李洁陈莺飞郑东宁 School of Science Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Institute of Physics Chinese Academy of Sciences

We carry out an ultra-low-field nuclear magnetic resonance （NMR） experiment based on high-T c superconducting quantum interference devices （SQUIDs）. The measurement field is in a micro-tesla range （～10 μT-100 μT） and the experiment is conducted in a home-made magnetically-shielded-room （MSR）. The measurements are performed by the indirect coupling method in which the signal of nuclei precession is indirectly coupled to the SQUID through a tuned copper coil transformer. In such an arrangement, the interferences of applied measurement and polarization field to the SQUID sensor are avoided and the performance of the SQUID is not destroyed. In order to compare the detection sensitivity obtained by using the SQUID with that achieved using a conventional low-noise-amplifier, we perform the measurements using a commercial room temperature amplifier. The results show that in a wide frequency range （～1 kHz-10 kHz） the measurements with the SQUID sensor exhibit a higher signal-to-noise ratio. Further, we discuss the dependence of NMR peak magnitude on measurement frequency. We attribute the reduction of the peak magnitude at high frequency to the increased field inhomogeneity as the measurement field increases. This is verified by compensating the field gradient using three sets of gradient coils.

关键词： indirect coupling measurement superconducting quantum interference devices low field nuclearmagnetic resonance

超导量子干涉仪及其在低场核磁共振及成像中的应用

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中国材料进展 2013年第9期32卷 541-549,561页

作者：王宁蒋凤英金贻荣李绍邓辉田野任育峰郑东宁中国科学院物理研究所北京100190

超导量子干涉仪利用约瑟夫森结宏观量子干涉效应,是一种具有超高灵敏度的磁通探测器件。对超导量子干涉仪的基本原理及其在低场核磁共振/成像技术中的应用进行了简要介绍,并报道了在这方面的主要研究成果。搭建了一套低场核磁共振及成... 详细信息

超导量子干涉仪利用约瑟夫森结宏观量子干涉效应,是一种具有超高灵敏度的磁通探测器件。对超导量子干涉仪的基本原理及其在低场核磁共振/成像技术中的应用进行了简要介绍,并报道了在这方面的主要研究成果。搭建了一套低场核磁共振及成像系统并获得具有较高信噪比的水样品1H质子NMR谱及三氟乙醇的纯J-耦合谱,同时还测到了清晰的自旋回波信号。在此基础上,采用直接背投影重建方法,尝试并成功获得了水样品和生物样品的一维及二维核磁共振像。采用8 nm粒径的超顺磁Fe3O4磁性纳米粒子作为对比增强剂,研究了磁性纳米粒子对1H核自旋纵向弛豫时间T1的影响,据此演示了磁性纳米粒子T1加权对比度增强成像实验,所得二维核磁共振像随极化时间的不同显示出显著的对比度变化。

关键词：超导量子干涉仪低场核磁共振核磁共振成像磁性纳米粒子

Fabrication and properties of the meander nanowires based on ultra-thin Nb films

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Chinese Physics B 2014年第8期23卷 521-526页

作者：赵璐金贻荣李洁邓辉郑东宁 Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences

We report the fabrication and the study of superconducting properties of ultra-thin Nb superconducting meander nanowires, which can be used as superconducting nanowire single-photon detectors （SNSPDs）. The ultra-thin （about 7- nm thick） Nb films are patterned into micro-bridges, and 100-nm wide meander nanowires by using e-beam lithography （EBL）. The average transition temperature （Tc） of the nanowires is about 4.8 K and the critical current density jc is about 2.8 × 10^6 A/cm2. Superconducting characteristics of the specimens at different applied magnetic fields up to 8 T （parallel or perpendicular to the specimen） are systematically investigated. The normalized temperature t （= T/Tc） dependences of the parallel critical field （HcⅡ） for both the micro-bridge and the meander nanowire are almost the same, following the Ginzburg and Landau （GL） formalism for ultra-thin films. However, in perpendicular field and in the vicinity of Tc （〉 0.95Tc）, the critical field Hc⊥ of the nanowire exhibits a down-turn curvature nonlinear temperature dependence while the micro-bridge displays a linear temperature dependence. The nonlinear behavior of Hc⊥ in the nanowire is believed to be due to the fact that in the vicinity of Tc the coherence length becomes larger than the line width. Additionally, the localization of carriers in the nanowire could also contribute to the nonlinear behavior. The resistive transitions could be described by the phase-slip model for quasi-one-dimensional system. Moreover, the hysteresis in I-V curve of the meander nanowires can be illustrated by a simple model of localized normal hotspot maintained by Joule heating.

关键词： Nb meander nanowire critical temperature critical field critical current