Nonresonant Casimir-Polder repulsion with a monolayer topological insulator

We investigate the behavior of the nonresonant Casimir-Polder force acting on a metastable polarized state of a two-level atomic system with a right-circularly polarized electric dipole transition in the presence of a monolayer topological insulator inhabiting an anomalous quantum Hall insulator state with a negative Chern number, finding that the force can be repulsive for a certain range within the far-field region. By considering stanene irradiated by circularly polarized monochromatic laser light as a material example of a monolayer topological insulator, we study the effect of the frequency dispersion in the conductivity tensor on the force behavior, finding that the dispersion generally leads to a slight downward shift of the force relative to that predicted by a nondispersive approximation, as well as a slight reduction of the range over which the force is repulsive.