Heat transfer statistics in extreme-near-field radiation

TL;DR

This paper analyzes the full counting statistics of heat transfer in extreme-near-field radiation, revealing how electron-electron interactions dominate and providing a way to evaluate heat current fluctuations via thermal conductance.

Contribution

It introduces a nonequilibrium Green's function approach with a Levitov-Lesovik like SCGF for heat transfer, accounting for electron-electron interactions in the near field.

Findings

Heat current fluctuation is proportional to thermal conductance times 2k_B T^2.

The SCGF satisfies a fluctuation symmetry relation.

In linear response, cumulants are expressed by lower order cumulants.

Abstract

We investigate the full counting statistics of extreme-near-field radiative heat transfer using nonequilibrium Green's function formalism. In the extreme near field, the electron-electron interactions between two metallic bodies dominate the heat transfer process. We start from a general tight-binding electron Hamiltonian and obtain a Levitov-Lesovik like scaled cumulant generating function (SCGF) using random phase approximation to deal with electron-electron interaction. The expressions of heat current and its fluctuation (second cumulant) are obtained from the SCGF. The fluctuation symmetry relation of the SCGF is verified. In the linear response limit (small temperature gradient), we express the heat current cumulant by a linear combination of lower order cumulants. The heat current fluctuation is $2k_B T^2$ times the thermal conductance with $T$ the average temperature in the linear response limit, and this provides an evaluation of heat current fluctuation by measuring the thermal conductance in extreme-near field-radiative heat transfer.