用于射频超导量子干涉器的新型单CSRR磁通聚焦器和谐振器

文提出了一种新型磁通聚焦器和谐振器. 磁通聚焦器引入了单互补开环谐振器结构 (单CSRR); 谐振器则采用环绕着绕磁通聚焦器的发夹型3阶阶梯阻抗谐振器 (SIR). 采用ANSYS HFSSv.11高频结构仿真软件对提出的磁通聚焦器和谐振器进行了仿真, 并对单CSRR进行了理论分析. 仿真和理论分析表明: 单CSRR的引入, 提高了磁通聚焦器的聚磁效果, 改善了磁通聚焦器与RF SQUID垫圈的耦合(耦合系数k_sc为引入单CSRR前的2倍), 并且有效面积增大到1.227 mm².     

阻尼型高温直流超导量子干涉器磁强计的设计

理论分析了超导环路与一个电阻并联结构的直流超导量子干涉器(dc-SQUID)的特性.给出了这种阻尼型dc-SQUID的电压噪声谱密度、传输函数和磁通噪声谱密度随偏置电流变化的曲线.与无阻尼型高温器件比较，调制参量β大于1的阻尼型高温dc-SQUID磁强计具有高稳定性和易调试等优点.当β大于4时，因传输函数的增大，阻尼型dc-SQUID还能降低它的磁通噪声谱密度从而提高磁强计的检测灵敏度.根据现有高温超导薄膜器件的工艺条件，设计了β等于4的阻尼型高温dc-SQUID磁强计的芯片、其磁通噪声和磁场噪声的理论值 关键词：     

介质谐振器法测量超导微波表面电阻

高温超导薄材料在微波器件中应用的出发点主要是利用它在临界温度下极低的表面电阻。因此要对超导器件性能作出准确的评估,必须精确测量超导薄膜的微波表面电阻。本文提出了利用蓝宝石介质圆柱的ＴＥ０１１谐振模式来测量超导微波表面电阻的一种方法。设计并制作了工作于１８．９ＧＨｚ和１７．６ＧＨｚ的两种高Ｑ值谐振器。其在测试中表现出了相当高的灵敏度。同时具有不损坏被测薄膜,安装调试简单方便,可重复性好的优点,可用于     

用于高TcrfSQUID的高Tc超导平面谐振器

我们设计并制备了用于高ＴｃｒｆＳＱＵＩＤ的超导平面谐振器，并测量了其谐振参数。实验表明，超导平面谐振器与分立元件式谐振器相比具有很高的品质因数，约为１０００－６０００。通过调节衬底材料，设计尺寸可以调节谐振频率。     

虚拟仪器在射频超导量子干涉仪控制电路中的应用

本文简要介绍LabVIEW开发的射频超导量子干涉器（rf SQUID）自动控制系统的虚拟仪器，系统可对超导量子干涉器的工作点进行调整和显示，实现了LabVIEW软件系统与第三方硬件的结合．本文将对系统工作原理、硬件电路组成和软件的设计做简要介绍．     

超导量子干涉器件

超导现象是一种宏观量子现象.磁通量子化和约瑟夫森效应是两个最能体现这种宏观量子特性的物理现象.超导量子干涉器件(superconducting quantum interference device,SQUID)是利用这两个特性而形成的超导器件.SQUID器件在磁信号灵敏探测方面具有广泛的应用.本文简要介绍低温超导和高温超导SQUID器件的相关背景和发展现状以及应用领域.     

虚拟仪器在射频超导量子干涉仪控制电路中的应用

本文简要介绍LabVIEW开发的射频超导量子干涉器(rf SQUID)自动控制系统的虚拟仪器,系统可对超导量子干涉器的工作点进行调整和显示,实现了LabVIEW软件系统与第三方硬件的结合.本文将对系统工作原理、硬件电路组成和软件的设计做简要介绍.     

用射频超导量子干涉器件测量高温超导体序参量的位相

利用射频超导量子干涉器件理论,提出了在一般的非回滞模式(β≤1,不限于β1)下测量高温超导体序参量对称性中相位信息的工作原理.以β=0.7为例对系统作了详细的讨论,给出在这个条件下用以测量序参量相位的射频偏置参量范围. 关键词：     

超导量子干涉器(SQUID)原理及应用

严谨的超导量子干涉器原理的阐述是非常深奥和繁杂的,我们在这里采用简明的物理图像和数学语言论述超导量子干涉器的原理及应用,以推动“大学物理现代化”的进程.     

串联超导量子干涉器件阵列制备与测试分析

串联超导量子干涉器件(superconducting quantum interference device,SQUID)阵列通过增加SQUID数量来达到提升信噪比的目的,即SQUID电压信号随SQUID数目比例增加而总电压噪声正比于SQUID数目的平方根值.本文介绍了利用自主工艺线进行串联SQUID阵列研究的相关研究...     

A new type of HTc superconducting film comb-shape resonator for radio frequency superconducting quantum interference devices

A new type of HTc superconducting film combshape resonator for radio frequency superconducting quantum interference devices (RF SQUID) has been designed. This new type of superconducting film comb-shape resonator is formed by a foursquare microstrip line without a flux concentrator. The range of the center frequency of this type of resonator varies from 800 MHz to 1 300 MHz by changing the length of the teeth. In this paper, we report on simulating the relationship of the value of the center frequency and the length of the teeth, and testing the noise of HTc RF SQUID coupling this comb-shape resonator. __________ Translated from Chinese Journal of Low Temperature Physics, 2005, 27(3) (in Chinese)     

高温超导量子干涉器中的约瑟夫森结

超导量子干涉器（SQUID）是以约瑟夫森结为核心元件的极其灵敏的磁通-电压转换器.在最近20年间,超导电子学界利用多种铜氧化物高温超导材料,制造出了高温超导约瑟夫森结乃至高温超导量子干涉器（高Tc SQUID）;特别是,利用YBa2Cu3O7-δ（YBCO）制出了多种高温超导约瑟夫森结,并进而制成了具有一定实用性的高Tc SQUID.文章主要是对高Tc SQUID中所使用的高温超导约瑟夫森结进行评述.     

Simulation of dielectric resonator for high-Tc radio frequency superconducting quantum interference device

Nowadays, the high-critical-temperature radio frequency superconducting quantum interference device (high-$T_{\rm c }$ rf SQUID) is usually coupled to a dielectric resonator that is a standard $10\times 10\times 1$~mm³ SrTiO$₃ (STO) substrate with a YBa₂Cu$₃O$_{7 - \delta }$ (YBCO) thin-film flux focuser deposited on it. Recently, we have simulated a dielectric resonator for the high-$T_{\rm c }$ rf SQUID by using the ANSOFT High Frequency Structure Simulator (ANSOFT HFSS). We simulate the resonant frequency and the quality factor of our dielectric resonator when it is unloaded or matches a 50-$\Omega$ impedance. The simulation results are quite close to the practical measurements. Our study shows that ANSOFT HFSS is quite suitable for simulating the dielectric resonator used for the high-$T_c rf SQUID. Therefore, we think the ANSOFT HFSS can be very helpful for investigating the characteristics of dielectric resonators for high-$T_c rf SQUIDs.     

Quantum search via superconducting quantum interference devices in a cavity

We propose a scheme for implementing the Grover search algorithm with two superconducting quantum interference devices (SQUIDs) in a cavity. Our scheme only requires single resonant interaction of the SQUID-cavity system and the required interaction time is very short. The simplicity of the process and the reduction of the interaction time are important for restraining decoherence.     

具有Washer型输入线圈的超导量子干涉放大器的制备与表征

超导量子干涉仪(SQUID)放大器具有低输入阻抗、低噪声、低功耗等优点, 目前被广泛用于微弱信号的检测领域. 与其他工艺相比, Nb/Al-AlO_x/Nb结构的约瑟夫森结具有相对较高的转变温度(T_c)、高的磁通电压调制系数以及良好的热循环能力、较宽的临界电流范围, 因此是制备SQUID放大器的很好选择. 设计并制作了欠阻尼、过阻尼约瑟夫森结以及具有Washer型输入线圈的单SQUID放大器, 通过在He³制冷机3 K温区下对器件电流-电压特性进行测量, 得到良好的结I-V特性曲线、SQUID调制特性, 初步实现利用SQUID进行放大作用, 并计算了SQUID的电流分辨率. 此项工作对于超导转变边沿传感器读出电路的实现具有重要的意义.     

MgO衬底上YBa2Cu3O7-δ台阶边沿型约瑟夫森结的制备及特性

MgO衬底上的YBa2Cu3O7-δ(YBCO)台阶边沿型约瑟夫森结(台阶结)在高灵敏度高温超导量子干涉器(superconducting quantum interference device,SQUID)等超导器件研制方面具有重要的应用价值和前景.本文对此类YBCO台阶结的制备和特性进行了研究.首先利用离子束刻蚀技术和两步刻蚀法在MgO(100)衬底上制备陡度合适、边沿整齐的台阶,然后利用脉冲激光沉积法在衬底上生长YBCO超导薄膜,进而利用紫外光刻制备出YBCO台阶结.在结样品的电阻-温度转变曲线中,观测到低于超导转变温度时的电阻拖尾现象,与约瑟夫森结的热激活相位滑移理论一致.伏安特性曲线测量表明结的行为符合电阻分路结模型,在超导转变温度TC附近结的约瑟夫森临界电流密度TC随温度T呈现出(TC-T)^2的变化规律,77 K时JC值为1.4×10^5 A/cm^2.利用制备的台阶结,初步制备了YBCO射频高温超导SQUID,器件测试观察到良好的三角波电压调制曲线,温度77 K、频率1 kHz时的磁通噪声为250μΦ0/Hz^1/2.本文结果为进一步利用MgO衬底YBCO台阶结研制高性能的高温超导SQUID等超导器件奠定了基础.     

Implementation of quantum partial search with superconducting quantum interference device qudits in cavity QED

We present a method to implement the quantum partial search of the database separated into any number of blocks with qudits,D-level quantum systems.Compared with the partial search using qubits,our method needs fewer iteration steps and uses the carriers of the information more economically.To illustrate how to realize the idea with concrete physical systems,we propose a scheme to carry out a twelve-dimensional partial search of the database partitioned into three blocks with superconducting quantum interference devices(SQUIDs)in cavity QED.Through the appropriate modulation of the amplitudes of the microwave pulses,the scheme can overcome the non-identity of the cavity–SQUID coupling strengths due to the parameter variations resulting from the fabrication processes.Numerical simulation under the influence of the cavity and SQUID decays shows that the scheme could be achieved efficiently within current state-of-the-art technology.     

超导量子计算核心器件

算力是数字经济时代新的生产力。量子计算基于量子力学的规律进行计算,人们普遍相信它可以在不久的将来在某些问题上完成经典计算机所无法完成的计算任务,实现量子优越性。作为最有可能实现通用量子计算的平台之一,以约瑟夫森结为核心元件的超导量子比特,在量子控制和量子测量方面具有稳定、可靠、便于设计和扩展等独特的优势,受到科学界甚至产业界的广泛关注,正在高速发展。文章围绕约瑟夫森结这一具有非线性和无耗散特征的超导量子器件,阐述了超导量子比特的基本原理及结构特征,重点介绍超导量子芯片设计、加工方面的前沿进展,并对未来发展方向进行简单的展望。     

Simulation of dielectric resonator for a high-To radio frequency superconducting quantum interference device

Nowadays, the high-critical-temperature radio frequency superconducting quantum interference device （high-Tc rf SQUID） is usually coupled to a dielectric resonator that is a standard 10× 10×1 mm^3 SrTiO3 （STO） substrate with a YBa2Cu3O7-δ （YBCO） thin-film flux focuser deposited on it. Recently, we have simulated a dielectric resonator for the high-Tc rf SQUID by using the ANSOFT High Frequency Structure Simulator （ANSOFT HFSS）. We simulate the resonant frequency and the quality factor of our dielectric resonator when it is unloaded or matches a 50-Ω impedance. The simulation results are quite close to the practical measurements. Our study shows that ANSOFT HFSS is quite suitable for simulating the dielectric resonator used for the high-Tc rf SQUID. Therefore, we think the ANSOFT HFSS can be very helpful for investigating the characteristics of dielectric resonators for high-Tc rf SQUIDs.