相干脉冲下磁通量子比特的几何量子计算

摘要

首先计算了旋转磁场下自旋1/2粒子的绝热几何相位.用微波电流脉冲控制量子比特,导致量子比特里产生振荡的磁场.这个效应可以通过一个扰动的哈密顿量增加到总哈密顿量里,对哈密顿量进行旋转变换,得到磁通量子比特哈密顿变化的总效果类似于一个自旋1/2粒子在旋转磁场中的行为,进而计算出相干脉冲下磁通量子比特的几何相位,给定参数得到单比特量子逻辑门.最后简述了基于几何相位设计两比特受控非门.%Firstly the adiabatic geometric phase of spin 1/2 particle under the rotating magnetic filed is calculated.The quantum bit produces oscillatory magnetic field under microwave current pulse.A perturbed Hamiltonian can be increased to the total Hamihonian,the total effect of flux qubits Hamiltonian variation is similar to a spin 1/2 particle' s behavior under the rotating magnetic field by rotating transformation.Then the geometric phase of flux qubits with coherent pulses and achieve one-bit quantum logic gate for certain parameters is calculated.Finally,two-bit controlled phase shift gate been have designed based on the Berry phase.