Temperature-dependent Casimir-Polder forces on polarizable molecules

TL;DR

This paper shows that thermal Casimir-Polder forces on molecules near conducting surfaces depend on temperature and molecular polarization, and can switch from attraction to repulsion at room temperature for anisotropically polarizable molecules.

Contribution

It reveals that temperature and polarization influence Casimir-Polder forces, enabling control over their attractive or repulsive nature, including room-temperature repulsion.

Findings

Force depends on temperature and molecular polarization.

Repulsion can be achieved at room temperature.

Force includes nonequilibrium effects from thermal photon interactions.

Abstract

We demonstrate that the thermal Casimir-Polder forces on molecules near a conducting surface whose transition wavelengths are comparable to the molecule-surface separation are dependent on the ambient temperature and molecular polarization and they can even be changed from attractive to repulsive via varying the temperature across a threshold value for anisotropically polarizable molecules. Remarkably, this attractive-to-repulsive transition may be realized at room temperature. Let us note that the predicted repulsion is essentially a nonequilibrium effect since the force we calculated on a ground-state (or an excited-stated) molecule actually contains the contribution of the absorption (or emission) of thermal photons.