Department of Physics, Fudan University, Shanghai, 200433, China.
Beijing Computational Science Research Center, Beijing, 100193, China.
Sci Rep. 2017 Jul 24;7(1):6254. doi: 10.1038/s41598-017-06157-4.
Dark state as a consequence of interference between different quantum states has great importance in the fields of chip-scale atomic clock and quantum information. For the Λ-type three-level system, this dark state is generally regarded as being dissipation-free because it is a superposition of two lowest states without dipole transition between them. However, previous studies are based on the rotating-wave approximation (RWA) by neglecting the counter-rotating terms in the system-environment interaction. In this work, we study non-Markovian quantum dynamics of the dark state in a Λ-type three-level system coupled to two bosonic baths and reveal the effect of counter-rotating terms on the dark state. In contrast to the dark state within the RWA, leakage of the dark state occurs even at zero temperature, as a result of these counter-rotating terms. Also, we present a method to restore the quantum coherence of the dark state by applying a leakage elimination operator to the system.
暗态是不同量子态之间干涉的结果，在片上原子钟和量子信息领域具有重要意义。对于 Λ 型三能级系统，由于它是两个最低态的叠加，它们之间没有偶极跃迁，因此通常认为这种暗态是无耗散的。然而，以前的研究是基于忽略系统-环境相互作用中反旋项的旋转波近似（RWA）。在这项工作中，我们研究了与两个玻色子浴耦合的 Λ 型三能级系统中暗态的非马尔可夫量子动力学，并揭示了反旋项对暗态的影响。与 RWA 中的暗态相比，即使在零温度下，由于这些反旋项的存在，暗态也会发生泄漏。此外，我们还提出了一种通过向系统施加泄漏消除算子来恢复暗态量子相干性的方法。
