Perturbation Theory for Open Two-Level Nonlinear Quantum Systems
Zhijie Zhang, Dong-Guang Jiang, Wei Wang · Communications in Theoretical Physics · 2011
Perturbation theory is an important tool in quantum mechanics. In this paper, we extend the traditional perturbation theory to open nonlinear two-level systems, treating decoherence parameter γ as a perturbation. By this virtue, we give a perturbative solution to the master equation, which describes a nonlinear open quantum system. The results show that for small decoherence rate γ, the ratio of the nonlinear rate C to the tunneling coefficient V (i.e., r = C / V ) determines the validity of the perturbation theory. For small ratio r , the perturbation theory is valid, otherwise it yields wrong results.