Skin-Depth Effect on the Casimir Force
Mariangela Lisanti, Davide Iannuzzi, and Federico Capasso
According to the theory of Quantum Electrodynamics, vacuum is filled with virtual photons that give rise to fluctuations of the electric and magnetic fields. These particles are responsible for the Casimir force, i.e. the attraction between two electrically neutral metallic surfaces. Studying the Casimir force between a metallized micromachined torsional device and a dielectric sphere coated with a thin metallic layer, we were able to demonstrate that, if the metallic layer is thin enough (~ 10 nm), the Casimir force is smaller compared to the case of a thick (250 nm), bulk-like metallic film. This is due to the finite penetration depth of the electromagnetic waves in a metal (skin depth), which leads to enhanced transparency in films.