Casimir-Polder interaction between an atom and a periodic nanostructure

We present a theory for the calculation of the Casimir-Polder potential experienced by an atom near the surface of a nanostructure. The potential is found by means of the electrodynamic Green's tensor based on a layer-multiple-scattering method. We calculate the distance law of the Casimir-Polder potential for a monolayer of metallic and dielectric nanospheres arranged periodically on a square lattice. We find, in particular, that the Casimir-Polder potential for a metallic nanostructure is practically independent of the type of the metal from which the nanostructure is made. Also, the Casimir-Polder potential shows an exponential decay close to the nanostructure and an inverse power-law decrease away from it wherein the exponent depends on the size of the spheres of the nanostructure.