方波外场下有限维量子系统的控制协议

Control protocol of finite dimensional quantum system using alternating square pulse

研究利用方型交替场进行有限维量子系统的控制协议.通过一个多循环的过程把量子系统控制到任意给定的目标态,在每个循环里利用方波脉冲控制系统能级间单个或几个跃迁.研究系统包括:除第1能级间隔外其他都一样的有限维系统;第1和第3能级间隔相等的4能级系统;各能级间隔都一样的3能级系统.目标态几率幅与系统与外场的作用时间以及系统的自由演化时间满足三角函数关系,并可解析地确定.

A control protocol to drive finite dimensional quantum systems to an arbitrary target state is proposed explicitly by using square pulses. It is a multi-cycle control process, and in each cycle we apply square pulses to cause a single or a few transitions between energy levels. Systems with equal energy gaps except for the first one, four-dimensional systems with equal first and third energy gaps but different second energy gap, and three- dimensional systems with all equal energy gaps are investigated in detail. The control parameters, namely the interaction time between systems and control fields as well as free evolution times between cycles, are connected with the probability amplitudes of target states via trigonometric functions and are determined analytically.