The quantized field in a dielectric and application to the radiative decay of an embedded atom

Weisskopf–Wigner theory applied to the macroscopically quantized field shows that the spontaneous emission rate of an excited atom is unaffected by a dielectric, rather than enhanced by a factor of the refractive index, as local-field effects are eliminated in the continuum approximation. Dielectric effects on an atom must be calculated microscopically.