Quantum local-field corrections and spontaneous decay

A recently developed scheme [S. Scheel, L. Knoll, and D.-G. Welsch, Phys. R ev. A 58, 700 (1998)] for quantizing the macroscopic electromagnetic field in linear dispersive and absorbing dielectrics satisfying the Kramers-Kroni g relations is used to derive the quantum local-field correction for the st andard virtual-sphere-cavity model. The electric and magnetic local-field o perators are shown to become approximately consistent with QED only if the polarization noise is fully taken into account. It is shown that the polari zation fluctuations in the local field can dramatically change the spontane ous decay rate, compared with the familiar result obtained from the classic al local-field correction. In particular, the spontaneous emission rate str ongly depends on the radius of the local-held virtual cavity. [S1050-2947(9 9)04008-1].