Complex orientation dependence of Casimir-Polder interaction induced by curvature and optical properties of the surface and the surrounding medium

TL;DR

This paper develops a systematic method to analyze how surface curvature and material properties influence the orientation of particles via Casimir-Polder interactions, with implications for nano-device engineering.

Contribution

It introduces a multiple scattering expansion approach to derive curvature corrections for Casimir-Polder interactions, revealing complex orientation behaviors influenced by surface curvature and material properties.

Findings

Small surface curvature can switch particle orientation preferences.

Material properties and curvature interplay affects stable orientations.

Thermal fluctuations diminish curvature-induced orientation effects.

Abstract

We employ a multiple scattering expansion to systematically derive curvature corrections to the Casimir-Polder (CP) interaction between small an-isotropic particles and general magneto-dielectric surfaces. Our results, validated against exact solutions, reveal a complex, distance-dependent interplay between material properties and surface curvature in determining stable particle orientations. We demonstrate that even small surface curvature can induce or eliminate switches in the preferred orientation, a quantum effect that is diminished by thermal fluctuations. This work provides a crucial understanding of how to engineer nano-particle orientation through tune-able parameters, offering significant implications for micro- and nano-mechanical device design.