Effect of coherence of nonthermal reservoirs on heat transport in a microscopic collision model

TL;DR

This study explores how the coherence in nonthermal reservoirs affects heat transport in a microscopic collision model, revealing phase-dependent heat flow directions and conductance behaviors.

Contribution

It introduces a microscopic collision model analyzing the impact of reservoir coherence on heat transport, including phase-dependent heat flow and effective temperature effects.

Findings

Heat current direction depends on phase difference between reservoirs.

Coherence can cause heat to flow from cold to hot reservoirs.

Steady heat current behavior varies with effective temperature and phase.

Abstract

We investigate the heat transport between two nonthermal reservoirs based on a microscopic collision model. We consider a bipartite system consisting of two identical subsystems, and each subsystem interacts with its own local reservoir, which consists of a large collection of initially uncorrelated ancillas. Then a heat transport is formed between two reservoirs by a sequence of pairwise collisions (inter-subsystem and subsystem-local reservoir). In this paper we consider two kinds of reservoir's initial states, the thermal state, and the state with coherence whose diagonal elements are the same as that of the thermal state and the off-diaganal elements are nonzero. In this way, we define the effective temperature of the reservoir with coherence according to its diagonal elements. We find that for two reservoirs having coherence the direction of the steady current of heat is different for different phase differences between the two initial states of two reservoirs, especially the heat can transfer from the "cold reservoir" to the "hot reservoir" in the steady regime for particular phase difference. And in the limit of the effective temperature difference between the two reservoirs $\Delta T\rightarrow0$, for most of the phase differences, the steady heat current increases with the increase of effective temperature until to the high effective temperature limit; while for the thermal state or particular phase difference the steady heat current decreases with the increase of temperature at high temperatures, and in this case the conductance can be obtained.