Nonequilibrium Dynamics with Finite-Time Repeated Interactions

TL;DR

This paper develops a coarse-grained master equation for quantum systems undergoing repeated, non-overlapping interactions with probes, capturing diverse thermalization and measurement-related phenomena.

Contribution

It introduces a versatile master equation framework valid for arbitrary interaction strengths and times, extending the understanding of quantum dynamics in repeated interaction scenarios.

Findings

Channels can produce out-of-equilibrium states like inverted Gibbs states.

Gapless probes act as indirect measurements, enabling energy transfer analysis.

The framework applies to various regimes, including thermalization and measurement-induced dynamics.

Abstract

We study quantum dynamics in the framework of repeated interactions between a system and a stream of identical probes. We present a coarse-grained master equation that captures the system's dynamics in the natural regime where interactions with different probes do not overlap, but is otherwise valid for arbitrary values of the interaction strength and mean interaction time. We then apply it to some specific examples. For probes prepared in Gibbs states, such channels have been used to describe thermalisation: while this is the case for many choices of parameters, for others one finds out-of-equilibrium states including inverted Gibbs and maximally mixed states. Gapless probes can be interpreted as performing an indirect measurement, and we study the energy transfer associated with this measurement.