Casimir-Polder force between an atom and a dielectric plate: thermodynamics and experiment

TL;DR

This paper investigates the thermodynamic behavior of the Casimir-Polder force between an atom and a dielectric plate, revealing inconsistencies in theoretical models when dc conductivity and screening effects are included, and comparing with experimental data.

Contribution

It demonstrates that the Lifshitz theory aligns with thermodynamics only when dc conductivity is ignored and shows that including screening effects contradicts experiments.

Findings

Thermodynamically consistent results are obtained when dc conductivity is disregarded.

Including dc conductivity or screening effects violates the Nernst heat theorem.

Experimental data do not support models with screening effects.

Abstract

The low-temperature behavior of the Casimir-Polder free energy and entropy for an atom near a dielectric plate are found on the basis of the Lifshitz theory. The obtained results are shown to be thermodynamically consistent if the dc conductivity of the plate material is disregarded. With inclusion of dc conductivity, both the standard Lifshitz theory (for all dielectrics) and its generalization taking into account screening effects (for a wide range of dielectrics) violate the Nernst heat theorem. The inclusion of the screening effects is also shown to be inconsistent with experimental data of Casimir force measurements. The physical reasons for this inconsistency are elucidated.