The van der Waals energy of atomic systems near absorbing and dispersing bodies

Within the frame of macroscopic quantum electrodynamics in causal media, a rigorous derivation of the van der Waals energy of an atomic system in the presence of an arbitrary arrangement of dispersing and absorbing dielectric bodies is given. As an application, the van der Waals potential of an atom in the presence of a dispersing and absorbing sphere is derived. Closed expressions for the long-distance (retardation) and short-distance (non-retardation) limits are given, and the effect of material absorption is discussed.