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任何量子存储和信息处理器时时刻刻都受困于外界环境的干扰或因为其他系统关联而引起的量子态外泄.为了应对这些问题,人们提出了多种量子调控方案.这其中一大类方案由快信号调制或者基于激光脉冲序列的动力学解耦构成,旨在压制量子存储器件的退相干,并且阻止系统状态的外泄或扩散.本文回顾了一些应用此类量子调控方案的工作.人们可以保护处于非马尔可夫耗散噪声中的量子存储器件;或者在免于外泄的前提下,控制系统以进行绝热演化.通过分析各类动力学方程,包括二阶微扰主方程、基于非微扰论的量子态扩散方程、以及由PQ分解得到的单变量主方程,发现快速信号调制的效果与所施加脉冲序列的形态关系微弱.脉冲序列只需能够有效地将系统本征频率调至高于环境截断频率,系统量子态退相干就可以再被压制住.量子调控的效果其实与调控脉冲序列的具体细节无关.人们可以使用任何形态的激光,包括理想脉冲、矩形波脉冲、随机脉冲,甚至噪声型脉冲.
Any quantum memory and information processor are always trapped in the external environment or because of other systems associated quantum state leakage.In order to deal with these problems, people have proposed a variety of quantum control programs.This one of the major categories The scheme consists of fast signal modulation or dynamic decoupling based on laser pulse sequences designed to suppress the decoherence of quantum memory devices and to prevent the leakage or diffusion of system states.This paper reviews some applications of such quantum control schemes. People can protect the quantum storage devices in non-Markov noise dissipation or control the system to conduct adiabatic evolution without leakage.After analyzing various kinds of dynamic equations including the second-order perturbation main equation, Based on the non-perturbed quantum state diffusion equation and the univariate main equation derived from PQ decomposition, it is found that the effect of the fast signal modulation is weakly related to the shape of the applied pulse sequence. The pulse sequence can only effectively divide the system eigenfrequency Adjusted to higher than the environmental cut-off frequency, the system quantum state decoherence can be suppressed again. The effect of quantum control and regulation pulse Independent of the particular details of the column. One can use a laser in any form, including ideal pulse, the rectangular wave pulse, random pulse, the pulse type even noise.