Non-trivial retardation effects in dispersion forces: From anomalous distance dependence to novel traps

TL;DR

This paper reveals that in medium-mediated dispersion forces, retardation effects can cause non-monotonous potentials, including sign changes and trapping, challenging traditional distance-dependent models.

Contribution

It demonstrates the complex, non-trivial retardation effects in dispersion forces within media, highlighting the need to consider full potential behavior rather than simplified asymptotes.

Findings

Retardation effects can change sign in medium-mediated interactions.

A trapping potential can emerge due to anomalous retardation behavior.

Traditional models may overlook complex potential features in media.

Abstract

In the study of dispersion forces, nonretarded, retarded and thermal asymptotes with their distinct scaling laws are regarded as cornerstone results governing interactions at different separations. Here, we show that when particles interact in a medium, the influence of retardation is qualitatively different, making it necessary to consider the non-monotonous potential in full. We discuss different regimes for several cases and find an anomalous behaviour of the retarded asymptote. It can change sign, and lead to a trapping potential.