Atom-atom interactions at and between metal surfaces at nonzero temperature - art. no. 062702

We have investigated the temperature-dependent Casimir-Polder interaction b etween two oscillators in the proximity of metal surfaces. The interaction near a single metal surface has much in common with the interaction in free space. However, at any finite temperature the long-range asymptote is equa l to the high-temperature asymptote. This asymptote, which originates not f rom the n = 0 term in the Matsubara summation but from thermal population o f the n > 0 terms, is F(R) = 2k(B)T alpha (2)(0)/R-6. This should be compar ed with the more rapidly decaying zero-temperature Casimir-Polder asymptote , F(R) approximate to -13 (h) over barc alpha (2)(0) (2 piR(7)). The intera ction in the midplane between two metallic surfaces is very different. The nonretarded interaction decreases exponentially and the interaction is domi nated by an enhanced Casimir-Polder-like asymptote. At large separations th is asymptote also decays exponentially. For any relevant temperatures the l ong-range asymptote is no longer equal to the high-temperature limit. In ot her words crossover to a classical limit found for the long-range interacti on in free space, and on a metal surface, is not always valid in a narrow c avity.