Interaction of single quantum emitter and dark plasmon supported by a metal nanoring

We explore the interaction between a quantum emitter and a metal nanoring by numerical solution of coupled Maxwell-Liouville equations. When the quantum emitter and nanoring are subjected to an incident plane wave, coupling between the quantum emitter and a dark plasmon supported by the nanoring gives rise to a similar lineshape to the familiar Fano type. It results from the excitation of a dark plasmon via intermediary participation of the quantum emitter. The dark plasmon is characterized through the width and shift parameters of the emitter peak in the absorption spectrum of the nanoparticle. Our results are obtained with the help of finite-difference time-domain method and a recently proposed symmetry-adapted averaging approach.