Environmental Coherence And Non-Markovian Dynamics

Open quantum dynamics can be divided into Markovian and non-Markovian processes. In recent years, non-Markovian dynamics have received extensive attention because of its extensive existence and important applications. The main work of this paper includes: the effect of environmental coherence on the non-Markovianity of system dynamics and the effect of the initial number of environmental excitations and its statistical distribution on the non-Markovianity of system dynamics.By considering a qubit system coupled to its environment via dephasing model, we investigate the effects of coherence and excitation of environments on the system dynamics, assumeing that the environment of the initial state is coherent state,squeezing state and mixed state. Some nontrivial and unexpected results are found.The number of environmental excitations serves to enhance the non-Markovianity of system dynamics, but the enhancement slows down with the increasing of excitation number. However, environmental coherent has different effects, which enhances in some cases and suppresses in other cases the non-Markovianity of system dynamics.