Radiative decay of an emitter due to non-Markovian interactions with dissipating matter

Abstract

It is known that the more tractable Markovian models of coupling suited for weak interactions may overestimate the Rabi frequency significantly, and alter the total decay rate marginally, when applied to the strong-coupling regime. Here we describe a more significant consequence of the non-Markovian interaction between a photon emitter and dissipating matter such as resonant plasmonic nanoparticles. We show a large increase of radiative decay and a diminished non-radiative loss, which unravels the mechanism behind the large enhancements of surface-enhanced-Raman-spectroscopy (SERS), as well as the anomalous enhancements of emission due to extremely small fully absorbing metal nanoparticles less than 10 nm in dimensions. We construct the mixture of pure states of the coupled emitter-nanoparticle system, unlike conventional methods that rely on the orthogonal modes of the nanoparticle alone.