Physical Review A
Relation between Huttner-Barnett QED in dielectrics and classical electrodynamics: Determining the dielectric permittivity
S. M. Dutra, K. Furuya
Abstract
In the Huttner-Barnett theory of QED in linear dispersive dielectrics with absorption [Europhys. Lett. 18, 487 (1992); Phys Rev. A 46, 4306 (1992)], a certain function of frequency $\ensuremath{\varepsilon}(\ensuremath{\omega})$ is interpreted as the dielectric permittivity of the medium. As the concept of permittivity is independent of the quantum nature of radiation, to fully justify their interpretation it should be demonstrated that the Huttner-Barnett $\ensuremath{\varepsilon}(\ensuremath{\omega})$ coincides with the result of a classical calculation of the permittivity for the microscopic model adopted. We give such a demonstration here. In addition, we show that the expression for $\ensuremath{\varepsilon}(\ensuremath{\omega})$ given by Huttner and Barnett can be considerably simplified. The simplified expression makes evident what classes of dielectric permittivity can be described within the Huttner-Barnett theory.