Flux qubit with a large loop size and tunable Josephson junctions  

作　　者：邓辉 于海峰 薛光明 田野 任建坤 吴玉林 黄克强 赵士平 郑东宁 

机构地区：[1]Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Chinese Physics B》2012年第4期93-98,共6页中国物理B（英文版）

基　　金：supported by the National Basic Research Program of China (Grant Nos. 2011CBA00106 and 2009CB929102);the National Natural Science Foundation of China (Grant Nos. 11104340, 11161130519, and 10974243)

摘　　要：We present the design of a superconducting flux qubit with a large loop inductance. The large loop inductance is desirable for coupling between qubits. The loop is configured into a gradiometer form that could reduce the interference from environmental magnetic noise. A combined Josephson junction, i.e., a DC-SQUID is used to replace the small Josephson junction in the usual 3-JJ （Josephaon junction） flux qubit, leading to a tunable energy gap by using an independent external flux line. We perform numerical calculations to investigate the dependence of the energy gap on qubit parameters such as junction capacitance, critical current, loop inductance, and the ratio of junction energy between small and large junctions in the flux qubit. We suggest a range of values for the parameters.We present the design of a superconducting flux qubit with a large loop inductance. The large loop inductance is desirable for coupling between qubits. The loop is configured into a gradiometer form that could reduce the interference from environmental magnetic noise. A combined Josephson junction, i.e., a DC-SQUID is used to replace the small Josephson junction in the usual 3-JJ （Josephaon junction） flux qubit, leading to a tunable energy gap by using an independent external flux line. We perform numerical calculations to investigate the dependence of the energy gap on qubit parameters such as junction capacitance, critical current, loop inductance, and the ratio of junction energy between small and large junctions in the flux qubit. We suggest a range of values for the parameters.

关 键 词：flux qubit four Josephson junctions tunable energy gap 

分 类 号：O511[理学—低温物理] TP38[理学—物理]