Perturbation methods for the non-Markovian quantum state diffusion equation
Jie Xu, Xinyu Zhao, Jun Jing, Lian-Ao Wu, Ting Yu · Journal of Physics A Mathematical and Theoretical · 2014
Two perturbation methods for the non-Markovian quantum state diffusion (NMQSD) equation are investigated in this paper. The first perturbation method under investigation is based on a functional expansion of the NMQSD equation, while the second expands the NMQSD equation in terms of coupling strength between the system and its environment. We compare the two perturbation methods by solving the dynamics of a bipartite system in which the two perturbation methods can be compared with the exact NMQSD equation. In addition, as an application, we provide an analytical solution for a special family of the systemʼs initial states, and discuss the entanglement dynamics based on this solution.