Boson-boson pure-dephasing model with non-Markovian properties

In this paper, we discuss the mechanism of pure-dephasing process with a newly proposed boson-boson model, namely, a bosonic field coupled to another bosonic bath in thermal equilibrium. Our model is fully solvable and can reproduce the pure-dephasing process which is usually described by the well-known spin-boson model, therefore offering a new perspective to understanding decoherence processes in open quantum systems of high dimension. We also show that this model admits a generically non-Markovian dynamics with respect to various different non-Markovian characterizations, i.e., the criteria based on divisibility, quantum regression formula and Wigner function, respectively. The criterion based on Wigner function is firstly proposed in this paper. For the case that the particle number of the pure-dephasing system is constrained to be 0 or 1, we analytically prove its equivalence to the criteria based on trace distance and divisibility. (C) 2018 Elsevier B.V. All rights reserved.