Impact of anisotropy on the interaction of an atom with a one-dimensional nano-grating

We study the interaction of an atom with a one-dimensional nano-grating within the framework of macroscopic QED, with special emphasis on possible anisotropic contributions. To this end, we first derive the scattering Green’s tensor of the grating by means of a Rayleigh expansion and discuss its symmetry properties and asymptotes. We then determine the Casimir–Polder potential of an atom with the grating. In particular, we find that strong anisotropy can lead to a repulsive Casimir–Polder potential in the normal direction.