Reversing Heat Flow by Coherence in a Multipartite Quantum System

TL;DR

This paper experimentally shows that internal quantum coherence within a multipartite system can reverse heat flow direction, offering new ways to control thermal processes using quantum properties.

Contribution

It demonstrates that internal quantum coherence alone can reverse heat flow without initial system-environment correlations, advancing quantum thermodynamics understanding.

Findings

Quantum coherence determines heat flow direction and magnitude.

Internal coherence can reverse heat flow without external correlations.

Experimental verification using a multipartite spin system.

Abstract

The second law of thermodynamics dictates that heat flows spontaneously from a high-temperature entity to a lower-temperature one. Yet, recent advances have demonstrated that quantum correlations between a system and its thermal environment can induce a reversal of heat flow, challenging classical thermodynamic expectations. Here, we experimentally demonstrate that internal quantum coherence in a multipartite spin system can also reverse heat flow, without relying on initial correlations with the environment. Under the collision model with cascade interaction, we verify that both the strength and the phase of the coherence term determine the direction and magnitude of energy transfer. These results enable precise control of heat flow using only local quantum properties.