We investigate the fate of coherence in the dynamical evolution of symmetry protected quantum systems. Under the formalism of system plus bath for open quantum systems, antiunitary symmetries exhibit significant differences from the unitary ones in protecting initial coherence. Specifically, taking advantage of the Lindblad master equation, we find that a pure state in the symmetry protected degenerate subspace will be decoherent even though both the system Hamiltonian and system-environment interaction respect the same antiunitary symmetry. In contrast, the coherence will persist when the protecting symmetry is unitary. We provide an elaborate classification table to illustrate what kinds of symmetry combinations are able to preserve the coherence of the initial state, which is confirmed in several concrete models of single spin-$3/2$ systems. It can also be applied to the Haldane phase in interacting topological systems. Our results could be helpful in exploring possible experimental realization of stable time-reversal symmetric topological states.

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开放量子系统中对称性保护相干的命运

我们研究了对称保护量子系统动态演化中相干性的命运。在开放量子系统的系统加浴的形式主义下，反酉对称在保护初始相干性方面表现出与酉对称的显着差异。具体来说，利用 Lindblad 主方程，我们发现即使系统哈密顿量和系统-环境相互作用都遵循相同的反酉对称性，对称保护退化子空间中的纯状态将是退相干的。相反，当保护对称是单一的时，一致性将持续存在。我们提供了一个详细的分类表来说明什么样的对称组合能够保持初始状态的相干性，这在单自旋的几个具体模型中得到了证实。$3/2$系统。它也可以应用于相互作用拓扑系统中的霍尔丹相。我们的结果可能有助于探索稳定的时间反转对称拓扑状态的可能实验实现。