Casimir-Polder Interaction of an Atom with a Cavity Wall Made of Phase-Change Material out of Thermal Equilibrium

TL;DR

This paper investigates how a phase-change material wall affects the Casimir-Polder force on various atoms out of thermal equilibrium, revealing significant force enhancement due to the material's phase transition.

Contribution

It provides numerical analysis of the Casimir-Polder interaction with a phase-change material wall, highlighting the impact of the dielectric-to-metal transition on force magnitude and gradient.

Findings

Force magnitude increases with phase transition.

Force gradient is significantly enhanced.

Results align with experimental measurements.

Abstract

We consider the out-of-thermal-equilibrium Casimir-Polder interaction between atoms of He$^*$, Na, Cs, and Rb and a cavity wall made of sapphire coated with a vanadium dioxide film which undergoes the dielectric-to-metal phase transition with increasing wall temperature. Numerical computations of the Casimir-Polder force and its gradient as the functions of atom-wall separation and wall temperature are made when the latter exceeds the temperature of the environment. The obtained results are compared with those in experiment on measuring the gradient of the Casimir-Polder force between $^{87}$Rb atoms and a silica glass wall out of thermal equilibrium. It is shown that the use of phase-change wall material increases significantly the force magnitude and especially the force gradient, as opposed to the case of dielectric wall.