Casimir-Polder interaction between an atom and a Chern insulator: topological signature and long-range repulsion

TL;DR

This paper explores how the topological properties of Chern insulators influence the Casimir-Polder force on nearby atoms, revealing conditions for long-range repulsion and a topological signature in the force.

Contribution

It demonstrates that the Casimir-Polder interaction can be repulsive and topologically signatures can be observed depending on atomic states and separations near Chern insulators.

Findings

Resonant Casimir-Polder force can be repulsive over large distances.

Metastable atomic states can experience repulsive nonresonant forces.

Topological signature appears at large separations, proportional to $(Ceta)^2/(1+(Ceta)^2)$.

Abstract

We consider the Casimir-Polder interaction between a two-level atomic system and a Chern insulator for both the resonant and nonresonant channels. For a right circularly polarized excited atomic state near a Chern insulator with a negative Chern number $C$, the resonant Casimir-Polder force can be monotonically repulsive over a large range of separations. In the presence of the same Chern insulator, a right circularly polarized metastable atomic state is expected to experience a repulsive nonresonant Casimir-Polder force over a certain range of atom-surface separations in the far-field region. At still greater separations, the nonresonant Casimir-Polder force is expected to become attractive and exhibit a topological signature, being proportional to $(C\alpha)^2/(1+(C\alpha)^2)$, where $\alpha$ is the fine-structure constant.