Quantum electrodynamics description of localized surface plasmons at a metal nanosphere

TL;DR

This paper develops a quantum electrodynamics framework for localized surface plasmons in metal nanospheres, accurately capturing their spectral properties and providing a tool for quantum plasmonics and nano-optics applications.

Contribution

It introduces a fully quantum electrodynamic model for LSPs in nanospheres that aligns with classical Mie theory and enables detailed electric field analysis.

Findings

Spectral profiles match classical Mie theory

Includes radiative effects like depolarization and broadening

Provides electric field distributions in near- and far-field

Abstract

A canonical quantization scheme for localized surface plasmons (LSPs) in a metal nanosphere is presented based on a microscopic model composed of electromagnetic fields, oscillators that describe plasmons, and a reservoir that describes excitations other than plasmons. The eigenmodes of this fully quantum electrodynamic theory show a spectrum that includes radiative depolarization and broadening, including redshifting from the quasi-static LSP modes, with increasing particle size. These spectral profiles correctly match those obtained with exact classical electrodynamics (Mie theory). The present scheme provides the electric fields per plasmon in both near- and far-field regions whereby its utility in the fields of quantum plasmonics and nano-optics is demonstrated.