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 system-environment 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.
Highlights
Whenever we want to describe the time evolution of a quantum system taking into account the effects of the surrounding environment, we can rely on the tools provided by the theory of open quantum systems [1, 2]
We have considered two generalized pure dephasing microscopic models, with different environmental states and system-environment interaction terms, leading to the same reduced system dynamics
We have shown how quantitatively and even qualitatively different features of the information contained in system-environment correlations and environmental states might well result in the same flow of information towards the open system, implying the same increase in the trace distance and the same amount of non-Markovianity in the dynamics
Summary
Whenever we want to describe the time evolution of a quantum system taking into account the effects of the surrounding environment, we can rely on the tools provided by the theory of open quantum systems [1, 2]. Changes, as measured via the trace distance, have been derived [21,22,23], and a similar result has recently been obtained for entropic distinguishability quantifiers [24] In addition to their quantitative content, these links suggest further evidence that the possible quantum nature of the system-environment correlations, in terms of the presence of entanglement [25] or non-zero discord [26,27,28], does not play any special role in producing memory effects, compared to mere classical correlations [29, 30].
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