A scalar photon theory for near-field radiative heat transfer

Abstract

We study a one-dimensional model of radiative heat transfer for which the effect of the electromagnetic 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.

Caroli formalism in near-field heat transfer between parallel graphene sheets

“…Appendix C: Evaluation of Self-energy 1. RPA Consider only one of the two sheets, the RPA retarded self-energy, in (k, ν) space reads 16,17 Π r jj ′ (q ⊥ , ω) = −…”

“…In the following we will show a characteristic distance ∼ 10 − 100 nm, being comparable to hv F /k B T or hv F /µ, and within and beyond which the different thermal flux behaviors show up. Starting from the scalar potential heat flux operator 16,17 ĵ = . .…”

Generalized first-principles method to study near-field heat transfer mediated by Coulomb interaction

“…The reported near-field enhancements exceed the value predicted by the PvH theory and have been partially explained by mechanisms such as phonon tunneling or potential contaminants [18][19][20]. On the other hand, many efforts have been devoted to developing microscopic theories beyond the fluctuational electrodynamics and a scalar field theory of heat transfer has been proposed [21][22][23][24]. In the extreme near field, the vector potential of current fluctuations is less important and the scalar potential of density fluctuations becomes dominant [25].…”

Coulomb-force-mediated heat transfer in the near field: Geometric effect

“…Although the E and B field themselves are gauge independent in Maxwell's equations, it is economical to consider only the instantaneous Coulomb charge interactions and ignore the retardation part of the field. Indeed, this has been done in a number of papers [11][12][13][14][15][16]. The usual approach along the line of Polder and van Hove (PvH) [3] or its generalization [17][18][19] is to separate the question into two problems, the first one is a material property problem, where the dielectric function is determined, the second is to solve the Maxwell equations.…”