Casimir manipulations: The orientation dependence of fluctuation-induced forces

TL;DR

This paper investigates how the Casimir force varies with the relative orientation of spheroidal objects, providing exact calculations at large distances and for scalar fields, revealing orientation-dependent effects.

Contribution

It explicitly quantifies the orientation dependence of Casimir forces for spheroids, including exact asymptotic results and optimal orientations.

Findings

Casimir force varies with spheroid orientation

Orientation dependence is explicitly calculated at large distances

Optimal spheroid orientation identified for specific configurations

Abstract

The Casimir interaction between two objects, or between an object and a plane, depends on their relative orientations. We make these angular dependences explicit by considering prolate or oblate spheroids. The variation with orientation is calculated exactly at asymptotically large distances for the electromagnetic field, and at arbitrary separations for a scalar field. For a spheroid in front of a mirror, the leading term is orientation independent, and we find the optimal orientation from computations at higher order.