Retarded Casimir-Polder force on an atom near reflecting microstructures

We derive the fully retarded energy shift of a neutral atom in two different geometries that are useful for modeling etched microstructures. First, we calculate the energy shift due to a reflecting cylindrical wire, and then we work out the energy shift due to a semi-infinite reflecting half-plane. We analyze the results for the wire in various limits of the wire radius and the distance of the atom from the wire, and obtain simple asymptotic expressions useful for estimates. For the half-plane we find an exact representation of the Casimir-Polder interaction in terms of a single fast converging integral, which is easy to evaluate numerically.