Three-body Casimir effects and non-monotonic forces

TL;DR

This paper investigates non-monotonic Casimir forces arising from collective three-body effects near conducting walls, using a scattering approach to analyze interactions between atoms and macroscopic objects.

Contribution

It introduces a scattering method to compute three-body Casimir effects involving anisotropic dipoles and higher multipoles, revealing non-monotonic force behaviors.

Findings

Non-monotonic forces can occur due to three-body interactions.

Higher multipoles significantly influence the force between macroscopic spheres.

Competition between two- and three-body effects explains observed phenomena.

Abstract

Casimir interactions are not pair-wise additive. This property leads to collective effects that we study for a pair of objects near a conducting wall. We employ a scattering approach to compute the interaction in terms of fluctuating multipoles. The wall can lead to a non-monotonic force between the objects. For two atoms with anisotropic electric and magnetic dipole polarizabilities we demonstrate that this non-monotonic effect results from a competition between two- and three body interactions. By including higher order multipoles we obtain the force between two macroscopic metallic spheres for a wide range of sphere separations and distances to the wall.