总线制8量子比特超导量子计算芯片设计与仿真  

Design and Simulation of a Bus-Mode 8-Qubit Superconducting Quantum Computing Chip

作　　者：余玄[1,2,3] 张颖珊 刘其春 蔡涵[1,2,3] 赵昌昊 刘建设[1,2,3] 陈炜[1,2,3] 

机构地区：[1]清华大学清华信息科学技术国家实验室,北京100084 [2]清华大学微电子与纳电子学系,北京100084 [3]清华大学微电子学研究所,北京100084

出　　处：《微纳电子技术》2016年第12期781-786,796,共7页Micronanoelectronic Technology

基　　金：国家重点基础研究发展计划(973计划)资助项目(2011CBA00304);浙江天景生公益基金会资助项目

摘　　要：为了完成Shor算法这类量子计算,需要更多的量子比特参与,同时需要延长量子比特的退相干时间,实现对量子比特更精准的调控。基于对以上要求的综合考虑,Xmon量子比特是一种目前最优的选择。设计了一个以Xmon为计算单元的总线制的8量子比特超导计算芯片,可以实现任意两个量子比特之间的耦合操作。首先根据实验基础设计量子比特与共面波导谐振腔的工作频率、量子比特的非谐性和谐振腔的品质因子。用Matlab软件仿真量子比特的能级,得到约瑟夫森能与电容充电能。其中约瑟夫森能的大小由约瑟夫森结的氧化时间长短控制,电容充电能则主要由Xmon的十字电容决定。由以上参数能够计算出量子比特与谐振腔的耦合强度与耦合电容,谐振腔的物理长度可以根据耦合电容的物理尺寸进行调节。然后根据不同的衬底工艺使用不同线宽以满足输入阻抗匹配的要求。使用Ledit绘图软件将以上物理尺寸表现在版图上。取出谐振腔的部分用HFSS软件仿真并调节其频率及品质因子,达到设计要求。量子比特的工作频率在测试时通过输入电流来调控。通过绘图与仿真,完成了一个可用于实验室加工制造并测试的总线制超导量子计算芯片版图。在此基础上,还设计了一种可以降低管脚数量的控制复用方案,为最终实现量子计算打下了一定基础。Vast qubits with longer decoherence time and more precise control are needed in order to implement Shor＇s algorithm.Considering all these requirements together,Xmon qubit is the optimal choice at present.A bus-mode 8-qubit superconducting computing chip using Xmon as the computing cell was designed,which allows coupling operatioin being applied between any two of them.Firstly,the working frequency of qubit and coplanar waveguide resonator,the anharmonicity of qubit and the quality factor of resonator were designed from past experiment experience.The energy of qubit was simulated by Matlab software,and the Josephson energy and capacitor charging energy were obtained.The Josephson energy altered with change of oxidation time,and capacitor charging energy mainly depended on the cross capacitor of Xmon.The coupling strength and coupling capacitance between the qubit and the resonator were derived from all those parameters,the physical length of the resonator can be adjusted by the physical size of the coupling capacitor.Then according to different substrate technologies,the line widths were used to satisfy the requirements of input impedance matching.Using Ledit software,those physical sizes were shown on the layout.A part of the resonator was simulated by HFSS software,and its frequency and quality factor were optimized to meet the design requirements.The working frequency of qubit was controlled by the incoming current when testing.Through drawing and simulation,a bus-mode superconducting quantum computing chip layout was designed for lab fabrication and test.Besides,the multiplex control for reducing pin number was designed,preparing for the final realization of quantum computing.

关 键 词：超导量子计算芯片 量子比特 量子总线 共面波导谐振腔 版图 

分 类 号：O471.1[理学—半导体物理]