Measurement of the Unusual Dielectric Response to Low-Frequency s-Polarized Evanescent Waves in Metals with {\break} Implications for the Casimir Effect

TL;DR

This study measures the magnetic field response of copper to low-frequency s-polarized evanescent waves, revealing discrepancies with classical Drude model predictions and impacting understanding of the Casimir effect.

Contribution

It provides the first precise experimental test showing the Drude model's limitations in describing s-polarized evanescent waves in metals.

Findings

Drude model predictions are inconsistent with measurements

Evanescent wave response differs from classical expectations

Implications for Casimir force calculations and condensed matter physics

Abstract

We report precision measurements of the lateral component of the oscillating magnetic field reflected from a copper plate, which is fully determined by s-polarized evanescent waves. The measurement data are compared with theoretical predictions of classical electrodynamics using the dielectric permittivity of copper as given by the Drude model. It is shown that these predictions are excluded by the measurement data which means that the currently used Drude model does not provide a complete description of the electromagnetic response of metals for s-polarized evanescent waves. The critical importance of this result for several fields of condensed matter physics and optics dealing with evanescent waves, including the Casimir effect, is discussed.