Dynamics of thermal Casimir-Polder forces on polar molecules

TL;DR

This paper investigates how thermal Casimir-Polder forces affect the near-surface trapping of cold polar molecules, revealing oscillatory behavior, force saturation at high temperatures, and the dynamics of thermalization.

Contribution

It provides a detailed analysis of thermal Casimir-Polder forces on polar molecules near surfaces, including oscillation patterns and force saturation effects at room temperature.

Findings

Casimir-Polder force oscillates with molecule-wall separation.

Force saturation occurs at high temperature due to cancellation effects.

Molecular thermalization leads to damping of spatial oscillations.

Abstract

We study the influence of thermal Casimir-Polder forces on the near-surface trapping of cold polar molecules, with emphasis on LiH and YbF near an Au surface at room temperature. We show that for a molecule initially prepared in its electronic and rovibrational ground state, the Casimir-Polder force oscillates with the molecule-wall separation. The non-resonant force contribution and the evanescent part of the resonant force contribution almost exactly cancel at high temperature which results in a saturation of the (attractive) force in this limit. A dynamical calculation reveals how the spatial oscillations die out as thermalisation of the molecule with its environment sets in.