Microscopic Theory of Modified Spontaneous Emission in a Dielectric

The modification of the radiative decay rate of a source atom embedded in a uniform, isotropic dielectric is calculated to first order in the density of the dielectric atoms using a microscopic approach. In contrast to the recent results of Crenshaw and Bowden [Phys. Rev. Lett. 85, 1851 (2000)], the decay rate is found to be consistent with macroscopic theories based on quantization of the field in the dielectric.