Effect of inter-system coupling on heat transport in a microscopic collision model

TL;DR

This study investigates how inter-system coupling affects heat transport and the validity of approximations in a bipartite quantum system, revealing that quantum correlations influence the approximation's accuracy and demonstrating thermal rectification effects.

Contribution

It provides a detailed analysis of the validity of ignoring inter-system interactions in collision models and links this validity to quantum correlations.

Findings

Approximation worsens then improves with increasing inter-system coupling for energy-preserving interactions.

Perfect thermal rectification occurs with non-energy preserving asymmetric interactions.

Quantum correlations inversely relate to the validity of the approximation.

Abstract

In this paper we consider a bipartite system composed of two subsystems each coupled to its own thermal environment. Based on a collision model, we mainly study whether the approximation (i.e., the inter-system interaction is ignored when modeling the system-environment coupling) is valid or not. We also address the problem of heat transport unitedly for both conventional energy-preserving system-environment interactions and non-energy preserving system-environment interactions. For the former interaction, as the inter-system interaction strength increases, at first this approximation gets worse as expected, but then counterintuitively gets better even for a stronger inter-system coupling. For the latter interaction with asymmetry, this approximation gets progressively worse. In this case we realize a perfect thermal rectification, and we can not find apparent rectification effect for the former interaction. Finally and more importantly, our results show that whether this approximation is valid or not is closely related to the quantum correlations between the subsystems, i.e., the weaker the quantum correlations, the more justified the approximation and vice versa.