On "cold" and thermal Casimir-Polder forces for an atom interacting with a heated plate

Expressions for the "cold" and thermal parts of the Casimir-Polder force for an atom interacting with the surface of a plate possessing an arbitrary temperature T has been analyzed within the framework of a fluctuational-electromagnetic interaction theory that was previously developed for the "small spherical particle-metal plate" system. It is emphasized that this situation is nonequilibrium, since atom in the ground state has T = 0. A general expression for the nonequilibrium (temperature-dependent) part of the Casimir-Polder force is obtained.