The Role of Surface Plasmons in The Casimir Effect

TL;DR

This paper investigates how surface plasmon modes influence the Casimir effect, revealing their significant role at various distances and their potential to modify the force through plasmon property manipulation.

Contribution

It provides an analytical evaluation of plasmonic contributions to the Casimir energy, highlighting their impact at both short and large mirror separations and introducing an adiabatic mode definition.

Findings

Surface plasmons can contribute repulsively to the Casimir energy at certain distances.

The plasmonic contribution is significant across different separation scales.

Manipulating surface plasmons could allow control over the Casimir force.

Abstract

In this paper we study the role of surface plasmon modes in the Casimir effect. The Casimir energy can be written as a sum over the modes of a real cavity and one may identify two sorts of modes, two evanescent surface plasmon modes and propagative modes. As one of the surface plasmon modes becomes propagative for some choice of parameters we adopt an adiabatic mode definition where we follow this mode into the propagative sector and count it together with the surface plasmon contribution, calling this contribution "plasmonic". We evaluate analytically the contribution of the plasmonic modes to the Casimir energy. Surprisingly we find that this becomes repulsive for intermediate and large mirror separations. The contribution of surface plasmons to the Casimir energy plays a fundamental role not only at short but also at large distances. This suggests possibilities to taylor the Casimir force via a manipulation of the surface plasmons properties.