We investigate the excited-state population of an open two-level atomic system under the quantum feedback control with non-Hermitian feedback Hamiltonian. We firstly derive the master equation under non-Hermitian feedback controls for the two-level atomic system by using the general measurement theory and then respectively discuss the effect of different feedback parameters on the excited-state population. The results show that the excited-state population can be effectively protected from dissipative environments by adjusting feedback parameters. Furthermore, two schemes to realize long-time excited-state population trapping are proposed. The one is under the quantum feedback control with parity-time (PT)-symmetric feedback Hamiltonian, and the other recovers to the Hermitian quantum-jump-based feedback control. These originally come from the fact that the decay of the open two-level atomic system can be completely balanced by feedback controls with proper feedback parameters.

我们研究了具有非埃尔米特反馈哈密顿量的量子反馈控制下的开放二级原子系统的激发态种群。首先利用通用测量理论推导了非能级两级原子系统在非赫米特反馈控制下的主方程，然后分别讨论了不同反馈参数对激发态总体的影响。结果表明，通过调整反馈参数，可以有效地保护受激态种群免受耗散环境的影响。此外，提出了两种实现长时间激发态人口陷阱的方案。一个受制于具有奇偶时间（PT）对称反馈哈密顿量的量子反馈控制，另一个恢复到基于Hermitian量子跳跃的反馈控制。