Decoherence in n-level quantum systems

Ting Yu

Sahel Ashhab, J. R. Johansson, Franco Nori

Longli Zheng, Yonggang Peng

In this paper, we investigate quantum decoherence dynamics of a two-level system in colored environments described by stochastic processes. We present the extension of the theoretical framework of the stochastic Liouville approach, and we employ the approach in studying the decoherence dynamics of the two-level system in typical colored environments: the Ornstein-Uhlenbeck environment, a simple fluctuating bottleneck environment, and the dichotomic (two-state) environment. The analytical expressions of the decoherence factor of a two-level system in colored environments are obtained by introducing the marginal average operator, whose eigenvalues and eigenfunctions provide different viewpoints from which to understand the behavior of the decoherence factor. In addition, the investigations provide us a potential way to manipulate the decoherence of the quantum system in colored environments.

Piotr Marecki

Yanhui Wang, Chunlei Jiang, Zhao-Hui Peng +2 more

Bang-bang(BB) decoupling schemes for low-level atom systems in the cases of adiabatic decoherence alone, amplitude decoherence alone, and the case of adiabatic and amplitude decoherence together have been fully discussed. And for arbitrary-level atom system in amplitude decoherence, BB decoupling scheme was also given. Here after a review, we give the BB decoupling scheme for an arbitrary-level atom system in general decoherence.

Jianyong Li, Jing Zhang

The decoherence suppression issue is studied for two-level quantum systems based on coherent control strategy.The model of two-level open quantum systems under coherent control is formulated,in which the decoherence suppression is equivalent to the decoupling problem of the system from environmental noises.Then,an open-loop control is designed to suppress decoherence,which is shown to be capable of asymptotically decoupling a part of the dynamic variables of the system from the environmental noises.Finally,feedback control strategy is introduced so that the corresponding state variables can be precisely decoupled form the environmental noises without being affected by the noises induced by quantum measurement in feedback control.