Nonlinear quantum heat transfer in hybrid structures: Sufficient conditions for thermal rectification

TL;DR

This paper provides a unified analytical framework for understanding nonlinear heat transfer and thermal rectification in hybrid quantum systems, identifying conditions and classes of rectifiers based on reservoir properties.

Contribution

It introduces sufficient conditions for thermal rectification in two-terminal quantum systems and classifies rectifiers into two distinct types based on reservoir characteristics.

Findings

Rich nonlinear current-temperature behavior observed.

Two classes of rectifiers identified: dissimilar density of states and differing particle statistics.

Thermal rectification is shown to be a widespread phenomenon.

Abstract

We present a unified description of heat flow in two-terminal hybrid quantum systems. Using simple models, we analytically study nonlinear aspects of heat transfer between various reservoirs: metals, solids, and spin baths, mediated by the excitation/relaxation of a central (subsystem) mode. We demonstrate rich nonlinear current-temperature characteristics, originating from either the molecular anharmonicity, or the reservoirs (complex) energy spectra. In particular, we establish sufficient conditions for thermal rectification in two-terminal junctions. We identify two classes of rectifiers. In type-A rectifiers the density of states of the reservoirs are dissimilar. In type-B rectifiers the baths are identical, but include particles whose statistics differ from that of the subsystem, to which they asymmetrically couple. Nonlinear heat flow, and specifically thermal rectification, are thus ubiquitous effects that could be observed in a variety of systems, phononic, electronic, and photonic.