Cai Xiangji, Feng Yanyan, Ren Jing, Peng Yonggang, Zheng Yujun
School of Science, Shandong Jianzhu University, Jinan 250101, China.
School of Physics, Shandong University, Jinan 250100, China.
J Chem Phys. 2024 Jul 28;161(4). doi: 10.1063/5.0217863.
We theoretically study the decoherence of a two-level quantum system coupled to noisy environments exhibiting linear and quadratic fluctuations within the framework of a stochastic Liouville equation. It is shown that the intrinsic energy levels of the quantum system renormalize under either the linear or quadratic influence of the environmental noise. In the case of quadratic dependence, the renormalization of the energy levels of the system emerges even if the environmental noise exhibits stationary statistical properties. This is in contrast to the case under linear influence, where the intrinsic energy levels of the system renormalize only if the environmental noise displays nonstationary statistics. We derive the analytical expressions of the decoherence function in the cases where the fluctuation of the frequency difference depends linearly and quadratically on the nonstationary Ornstein-Uhlenbeck noise (OUN) and random telegraph noise (RTN) processes, respectively. In the case of the linear dependence of the OUN, the environmental nonstationary statistical property can enhance the dynamical decoherence. However, the nonstationary statistics of the environmental noise can suppress the quantum decoherence in this case under the quadratic influence of the OUN. In the presence of the RTN, the quadratic influence of the environmental noise does not give rise to decoherence but only causes a determinate frequency renormalization in dynamical evolution. The environmental nonstationary statistical property can suppress the quantum decoherence of the case under the linear influence of the RTN.
我们在随机刘维尔方程的框架内，从理论上研究了一个与呈现线性和二次涨落的噪声环境耦合的两能级量子系统的退相干。结果表明，在环境噪声的线性或二次影响下，量子系统的本征能级会发生重整化。在二次依赖的情况下，即使环境噪声呈现平稳统计特性，系统能级的重整化也会出现。这与线性影响下的情况形成对比，在后者中，只有当环境噪声显示非平稳统计特性时，系统的本征能级才会重整化。我们分别推导了频率差涨落在非平稳奥恩斯坦 - 乌伦贝克噪声（OUN）和随机电报噪声（RTN）过程中线性和二次依赖情况下的退相干函数的解析表达式。在OUN线性依赖的情况下，环境非平稳统计特性可以增强动态退相干。然而，在OUN的二次影响下，环境噪声的非平稳统计特性在这种情况下可以抑制量子退相干。在存在RTN的情况下，环境噪声的二次影响不会导致退相干，而只会在动态演化中引起确定的频率重整化。环境非平稳统计特性可以抑制RTN线性影响下的量子退相干。
