We consider vacuum fluctuations of the quantum electromagnetic field in the
presence of an infinite and perfectly conducting plate. We evaluate how the
change of vacuum fluctuations due to the plate modifies the Casimir-Polder
potential between two atoms placed near the plate. We use two different methods
to evaluate the Casimir-Polder potential in the presence of the plate. They
also give new insights on the role of boundary conditions in the Casimir-Polder
interatomic potential, as well as indications for possible generalizations to
more complicated boundary conditions.Comment: 10 page