Protecting Coherence and Entanglement by Quantum Feedback Controls
Protecting Coherence and Entanglement by Quantum Feedback Controls
复制标题
通过量子反馈控制保护相干性和纠缠
DOI：
10.1109/tac.2009.2039238
复制
发表时间：
2010-03-01
影响因子：
6.8
通讯作者：
Tarn, Tzyh-Jong
中科院分区：
文献类型：
--
作者：
Zhang, Jing;Wu, Re-Bing;Tarn, Tzyh-Jong
当量子系统与其环境相互作用时，所谓的退相干效应通常会破坏量子态的相干性及其子系统之间的纠缠。我们提出了一种基于量子弱测量的反馈控制策略，以保护量子态的相干性和纠缠不受环境扰动的影响。对于振幅阻尼和退相消相干通道下的单量子比特量子系统，我们的策略可以根据其两个能级之间的布居差的测量信息来保持相干性。对于一个通过独立的振幅阻尼和退相消相干通道解纠缠的两量子比特系统，所设计的反馈控制通过调节两量子比特之间的耦合强度，可以保持基态和最高激发态之间的相干性，同时使两量子比特之间的纠缠损失最小化.作为动力学对称性的结果，这些结果的推广导出了控制诱导的无消相干可观测子空间的概念，并给出了几个判据。
When a quantum system interacts with its environment, the so-called decoherence effect will normally destroy the coherence in the quantum state and the entanglement between its subsystems. We propose a feedback control strategy based on quantum weak measurements to protect coherence and entanglement of the quantum state against environmental disturbance. For a one-qubit quantum system under amplitude damping and dephasing decoherence channels, our strategy can preserve the coherence based on the measured information about the population difference between its two levels. For a two-qubit quantum system disentangled by independent amplitude damping and dephasing decoherence channels, the designed feedback control can preserve coherence between the ground state and the highest excited states by tuning the coupling strength between the two qubits, and at the same time minimize the loss of entanglement between the two qubits. As a consequence of dynamic symmetry, the generalization of these results derives the concept of control-induced decoherence-free observable subspace, for which several criteria are provided.