Hermitian description of localized plasmons in dispersive dissipative subwavelength spherical nanostructures

Abstract

The canonical quantization procedure in dispersive and lossy media assumes the eigenstates of the system to be collective excitations of the electromagnetic field and reservoir degrees of freedom. In this paper, we show that in low loss limit, the collective plasmonic modes in a quasistatic approximation separate from the reservoir. As an example, we consider the localized surface plasmon on a spherical metallic nanoparticle in a vacuum and find the macroscopic longitudinal electric near field per plasmon in the cases of gold and silver. Using our canonical approach, we calculate the correction to the electric near field per plasmon obtained from phenomenological quantization. The canonical conjugated variable to the electric near field is determined.