Currents and fluctuations of quantum heat transport in harmonic chains

TL;DR

This paper introduces a non-perturbative stochastic Liouville-von Neumann approach to analyze heat transport and fluctuations in open quantum harmonic chains, capturing strong coupling effects and correlations.

Contribution

It develops a general, efficient formalism for quantum heat currents and fluctuations that overcomes limitations of perturbative methods, especially in strong coupling regimes.

Findings

Strong coupling enhances reservoir fluctuation effects.

Spatiotemporal heat transfer patterns differ from weak coupling predictions.

Second order moments reveal complex bath-bath correlations.

Abstract

Heat transport in open quantum systems is particularly susceptible to the modeling of system-reservoir interactions. It thus requires to consistently treat the coupling between a quantum system and its environment. While perturbative approaches are successfully used in fields like quantum optics and quantum information, they reveal deficiencies, typically in the context of thermodynamics, when it is essential to respect additional criteria such as fluctuation-dissipation theorems. We use a non-perturbative approach for quantum dissipative dynamics based on a stochastic Liouville-von Neumann equation to provide a very general and extremely efficient formalism for heat currents and its correlations in open harmonic chains. Specific results are derived not only for first but also for second order moments which requires to account for both real and imaginary parts of bath-bath correlation functions. Spatiotemporal patterns are compared with weak coupling calculations. The regime of stronger system-reservoir couplings gives rise to an intimate interplay between reservoir fluctuations and heat transfer far from equilibrium.