On the connection between microscopic description and memory effects in open quantum system dynamics

Abstract

The exchange of information between an open quantum system and its environment allows us to discriminate among different kinds of dynamics, in particular detecting memory effects to characterize non-Markovianity. Here, we investigate the role played by the system-environment correlations and the environmental evolution in the flow of information. First, we derive general conditions ensuring that two generalized dephasing microscopic models of the global systemenvironment evolution result exactly in the same open-system dynamics, for any initial state of the system. Then, we use the trace distance to quantify the distinct contributions to the information inside and outside the open system in the two models. Our analysis clarifies how the interplay between system-environment correlations and environmental-state distinguishability can lead to the same information flow from and toward the open system, despite significant qualitative and quantitative differences at the level of the global evolution.

Collision models in open system dynamics: A versatile tool for deeper insights?

“…In particular it allows to introduce additional figures of merit for non-Markovianity, such as the memory depth [38,[57][58][59], which quantifies the amount of environmental degrees of freedom that should be kept track of in order to obtain a Markovian description for the dressed system. In such a way one can also clarify that it is not the presence of correlations per se which warrants non-Markovianity, but rather their influence on the reduced state, indeed different correlations and environmental changes can lead to the very same reduced dynamics [60].…”