Effect of Curvature and Confinement on the Casimir-Polder Interaction

TL;DR

This paper investigates how confinement inside a cylindrical cavity and curvature affect Casimir-Polder interactions, revealing suppression effects and providing theoretical insights into modified quantum forces.

Contribution

It introduces a scattering approach to analyze the effects of cylindrical confinement and curvature on Casimir-Polder interactions for atoms and macroscopic spheres.

Findings

Confinement suppresses Casimir-Polder forces between atoms.

Theoretical framework includes retardation and thermal effects.

Agreement with proximity approximation at short separations.

Abstract

Modifications of Casimir-Polder interactions due to confinement inside a cylindrical cavity and due to curvature in- and outside the cavity are studied. We consider a perfectly conducting cylindrical shell with a single particle (atom or macroscopic sphere) located next to its interior or exterior surface, or two atoms placed inside the shell. By employing the scattering approach, we obtain the particle-cavity interaction and the modification of the two-particle interaction due to the cavity. We consider both retardation and thermal effects. While for the atoms a dipole description is sufficient, for the macroscopic sphere we sum (numerically) over many multipole fluctuations to compute the interaction at short separations. In the latter limit we compare to the proximity approximation and a gradient expansion and find agreement. Our results indicate an confinement induced suppression of the force between atoms. General criteria for suppression and enhancement of Casimir interactions due to confinement are discussed.