A scalar photon theory for near-field radiative heat transfer

TL;DR

This paper introduces a scalar photon model for near-field radiative heat transfer, focusing on scalar potential effects at nanometer scales, and explains experimental phenomena with new theoretical insights.

Contribution

The paper develops a scalar photon theory using quantized scalar fields to model near-field heat transfer, differing from traditional electrodynamics approaches.

Findings

Scalar photon theory explains enhanced heat transfer at nanometer scales.

The model accounts for charge fluctuation effects observed experimentally.

Thermal rectification effects are predicted due to asymmetric couplings.

Abstract

We study a one-dimensional model of radiative heat transfer for which the effect of the electromag- netic field is only from the scalar potential and thereby ignoring the vector potential contribution. This is a valid assumption when the distances between objects are of the order of nanometers. Using Lorenz gauge, the scalar field is quantized with the canonical quantization scheme, giving rise to scalar photons. In the limit as the speed of light approaches infinity, the theory reduces to a pure Coulomb interaction governed by the Poisson equation. The model describes very well parallel plate capacitor physics, where a new length scale related to its capacitance emerges. Shorter than this length scale we see greater radiative heat transfer. This differs markedly from the usual Rytov fluctuational electrodynamics theory in which the enhancement is due to evanescent modes shorter than the thermal wavelengths. Our theory may explain recent experiments where charge fluctuations instead of current fluctuations play a dominant role in radiative heat transfer. Finally, due to the asymmetric electron-bath couplings, thermal rectification effects are also observed and reported.