Two-time correlation functions in an exactly solvable spin-boson model

摘要

We consider a spin-boson model describing the dephasing process in an open quantum system and obtain exact expressions for the two-time spin correlation function and the decoherence function applicable for any values of the coupling constants. We show that the initial statistical correlations between the dynamical system and the heat bath considerably affect the time dependence of the decoherence function.