基于量子反馈保护量子比特的相干性

Protection of Quantum Coherence of Qubit Based on Quantum Feedback

通过采用直接的量子反馈方法控制量子比特的量子相干性,研究了与单模腔相互作用的量子比特的量子相干性的动力学演化。利用l_1范数相干性和量子相对熵相干性描述量子系统的相干性,分析了量子反馈和外部驱动对系统相干性演化的影响。研究结果表明,两种相干性表现出相同的动力学特性,量子反馈减慢了量子相干性的衰减,在一定程度上保护了量子相干性。若考虑外部驱动,在强驱动下,长时极限的稳态的量子相干性为零,而在非强驱动下相干性达到一个不变的最大值。

Based on the direct quantum feedback method for controlling the quantum coherence of a qubit, the dynamical evolution of the quantum coherence of a qubit which interacts with a single mode cavity is investigated. By using the l1 norm of coherence and the relative entropy of coherence to quantify the quantum coherence, the effects of the quantum feedback and the external driving on the evolution of the quantum coherence are analyzed. The research results show that, the dynamical characteristics of these two types of coherences are the same. The quantum feedback slows the decay of the quantum coherence and plays a certain protective role. When the external driving is considered, the coherence of the steady state in the long limit becomes zero under the strong-driving condition, while the quantum coherence reaches a stable maximum value under the non-strong-driving condition.