Geometrical dependence in Casimir-Polder repulsion

TL;DR

This paper investigates how the geometry of an anisotropic annular disc influences Casimir-Polder repulsion, revealing torsion free points and a new repulsive regime in the ring limit.

Contribution

It introduces the concept of torsion free points on an anisotropic annular disc and demonstrates their role in the orientation dependence of Casimir-Polder forces.

Findings

Identification of torsion free points affecting orientation dependence

Discovery of new repulsion in the ring limit of the disc

Geometrical dependence of quantum vacuum-induced forces

Abstract

Repulsion, induced from quantum vacuum fluctuations, for an anisotropically polarizable atom on the symmetry axis of an anisotropically polarizable annular disc is studied. There exists two torsion free points on each side of the annular disc, where the interaction energy is orientation independent. The position of second of the two torsion free points, on either side of the disc, is shown to determine the orientation dependence of the atom at distances far from the plate, revealing a geometrical dependence. In the ring limit of the annular disc, new repulsion emerges.