Exact microscopic theory of electromagnetic heat transfer between a dielectric sphere and plate

TL;DR

This paper presents a rigorous microscopic theory and computational method for electromagnetic heat transfer between a dielectric sphere and a plate, enabling accurate predictions beyond the blackbody limit in near-field conditions.

Contribution

It introduces the first exact theoretical calculation for heat transfer in a sphere-plate geometry, unifying previous approximations and offering new insights for experimental design.

Findings

Quantitative calculation of heat transfer beyond blackbody limit

Unified theoretical framework for sphere-plate geometry

Enhanced understanding for experimental exploration of near-field heat transfer

Abstract

Near-field electromagnetic heat transfer holds great potential for the advancement of nanotechnology. Whereas far-field electromagnetic heat transfer is constrained by Planck's blackbody limit, the increased density of states in the near-field enhances heat transfer rates by orders of magnitude relative to the conventional limit. Such enhancement opens new possibilities in numerous applications, including thermal-photo-voltaics, nano-patterning, and imaging. The advancement in this area, however, has been hampered by the lack of rigorous theoretical treatment, especially for geometries that are of direct experimental relevance. Here we introduce an efficient computational strategy, and present the first rigorous calculation of electromagnetic heat transfer in a sphere-plate geometry, the only geometry where transfer rate beyond blackbody limit has been quantitatively probed at room temperature. Our approach results in a definitive picture unifying various approximations previously used to treat this problem, and provides new physical insights for designing experiments aiming to explore enhanced thermal transfer.