Department of Electrical Engineering, Princeton University, New Jersey 08544, USA.
Phys Rev Lett. 2019 Feb 1;122(4):043601. doi: 10.1103/PhysRevLett.122.043601.
We study a cavity-QED setup consisting of a two-level system coupled to a single cavity mode with two-photon relaxation. The system dynamics is modeled via a Lindblad master equation consisting of the Rabi Hamiltonian and a two-photon dissipator. We show that an even-photon relaxation preserves the Z_{2} symmetry of the Rabi model, and provide a framework to study the corresponding non-Hermitian dynamics in the number-parity basis. We discuss the role of different terms in the two-photon dissipator and show how one can extend existing results for the closed Rabi spectrum to the open case. Furthermore, we characterize the role of the Z_{2} symmetry in the excitation-relaxation dynamics of the system as a function of light-matter coupling. Importantly, we observe that initial states with even-odd parity manifest qualitatively distinct transient and steady state behaviors, contrary to the Hermitian dynamics that is only sensitive to whether or not the initial state is parity invariant. Moreover, the parity-sensitive dynamical behavior is not a creature of ultrastrong coupling and is present even at weak coupling values.
我们研究了一个由两能级系统与单模腔耦合而成的腔 QED 系统，其中存在双光子弛豫。系统动力学通过包含拉比哈密顿量和双光子耗散项的林德布莱德主方程来建模。我们表明，偶数光子弛豫会保持拉比模型的 Z_2 对称性，并提供了一个在奇偶数基下研究相应非厄米动力学的框架。我们讨论了双光子耗散项中不同项的作用，并展示了如何将封闭拉比谱中的已有结果扩展到开放情况。此外，我们还研究了 Z_2 对称性在光物质耦合作用下对系统激发弛豫动力学的影响。重要的是，我们发现奇偶性初始态的瞬态和稳态行为表现出明显的不同，这与仅对初始态是否具有宇称不变性敏感的厄米动力学相反。此外，这种对宇称敏感的动力学行为不是强耦合的产物，即使在弱耦合值下也存在。
