Local-field correction to the spontaneous decay rate of atoms embedded in bodies of finite size

Abstract

The influence of the size and shape of a dispersing and absorbing dielectric body on the local-field corrected spontaneous-decay of an excited atom embedded in the body is studied on the basis of the real-cavity model. By means of a Born expansion of the Green tensor of the system it is shown that to linear order in the susceptibility of the body the decay rate exactly follows Tomaš's formula found for the special case of an atom at the center of a homogeneous dielectric sphere [Phys. Rev. A 63, 053811 (2001)]. It is further shown that for an atom situated at the interior of an arbitrary dielectric body this formula remains valid beyond the linear order. The case of an atom embedded in a weakly polarizable sphere is discussed in detail.

Local-field correction in the strong-coupling regime

“…This decomposition is not only helpful in the study of the local-field correction in the weak-coupling regime [19], but, as we shall see below, it also proves to be insightful in the strong-coupling regime.…”

“…(19) and (7) and performing an expansion in terms of k A R C , we recover the expansion (18) where the scattering part of the Green tensor of the resonator in the absence of the cavity, also in the limit 1 → ∞, is explicitly given by…”

“…[12] and later proved in Ref. [19] for an arbitrary geometry of the material body surrounding the guest atom that the Green tensor can be decomposed as…”

“…First we make use of the small-cavity expansion (18) and second we elucidate its domain of validity in the strong-coupling regime (for its applicability in the weak-coupling regime see Ref. [19]). Recall that the resonator consists of three layers, the innermost one being the cavity in the real-cavity model [ Fig.…”

“…The effect of finite size and shape of the host medium on the local field for weak atom-field coupling has been considered recently [12,19]. In this regime the dynamics of the atomic upper-level population just follows an exponential decaying law.…”