Probabilistic quantum control via indirect measurement
Probabilistic quantum control via indirect measurement
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DOI：
10.1103/physreva.71.013406
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发表时间：
2004-08
影响因子：
2.9
通讯作者：
A. Mandilara;J. W. Clark
中科院分区：
文献类型：
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作者：
A. Mandilara;J. W. Clark
量子控制的最基本场景包括通过么正变换有组织地操纵系统的纯动力学状态。最近，Vilela Mendes和Man‘ko已经证明，如果可以用射影测量来补充么正控制操作，则状态空间上的可控性条件变得不那么严格。本文正是基于这一思想，引入了间接测量的附加要素，实现了一种远程控制。要被远程控制的目标系统首先与另一个相同的系统纠缠在一起，称为控制系统。然后对控制系统进行么正变换和射影测量。正如薛定谔所预料的那样，这种通过纠缠进行的控制在本质上必然是概率的。另一方面，在适当的条件下，远程控制场景提供了对退相干的健壮性和更大的么正变换曲目的特殊优势。对一个两级系统进行的仿真表明，通过优化控制参数，可达状态的种群可以获得较大的增益。
The most basic scenario of quantum control involves the organized manipulation of pure dynamical states of the system by means of unitary transformations. Recently, Vilela Mendes and Man'ko have shown that the conditions for controllability on the state space become less restrictive if unitary control operations may be supplemented by projective measurement. The present work builds on this idea, introducing the additional element of indirect measurement to achieve a kind of remote control. The target system that is to be remotely controlled is first entangled with another identical system, called the control system. The control system is then subjected to unitary transformations plus projective measurement. As anticipated by Schroedinger, such control via entanglement is necessarily probabilistic in nature. On the other hand, under appropriate conditions the remote-control scenario offers the special advantages of robustness against decoherence and a greater repertoire of unitary transformations. Simulations carried out for a two-level system demonstrate that, with optimization of control parameters, a substantial gain in the population of reachable states can be realized.