路径积分方法研究Josephson结量子比特系统退相干

Studying decoherence of Josephson qubit by path intergration

利用迭代张量乘积法数值路径积分技术研究了开放Josephson结量子比特系统的退相干.数值计算结果表明:当环境可用欧姆库模拟时,Josephson结电荷量子比特系统约化密度矩阵非对角项的包络线是振荡的,且Hamiltonian量中磁场x方向分量Bx与磁场z方向分量Bz的值越接近,系统约化密度矩阵非对角项ρ12的振荡越强,退相干时间也逐渐变长.

Investigate the decoherence of open Josephson qubit system by iterative tensor multiplication algorithm based on numerical path integral technique.The numerical results show that when the environment is simulated by Ohmic bath,the envelope curves of the reduced density matrix’s off-diagonal coherent term are oscillatory.And the more x directional component of magnetic field approaches to z directional component of magnetic field,the stronger oscillation of off-diagonal coherent term is.Now the decoherence time is longer.