The electromagnetic field near a dielectric half-space

TL;DR

This paper calculates electromagnetic field expectations near a dielectric half-space, predicting Casimir-Polder forces and energy densities, with implications for understanding quantum vacuum effects in dielectric materials.

Contribution

It provides the first detailed computation of electromagnetic field fluctuations and energy densities near a dielectric half-space, extending Casimir effect analysis to dielectric boundaries.

Findings

Electromagnetic energy density near dielectric half-space is positive.

Casimir-Polder force predictions for atoms near dielectric surfaces.

Total energy density between two dielectric half-spaces is likely positive.

Abstract

We compute the expectations of the squares of the electric and magnetic fields in the vacuum region outside a half-space filled with a uniform non-dispersive dielectric. This gives predictions for the Casimir-Polder force on an atom in the `retarded' regime near a dielectric. We also find a positive energy density due to the electromagnetic field. This would lead, in the case of two parallel dielectric half-spaces, to a positive, separation-independent contribution to the energy density, besides the negative, separation-dependent Casimir energy. Rough estimates suggest that for a very wide range of cases, perhaps including all realizable ones, the total energy density between the half-spaces is positive.