Controlling the Purcell effect and the Lamb shift with nanoantenna-emitter hybrids

Light emission from single emitters, such as organic molecules, quantum dots, or nitrogen vacancies in nanocrystals strongly depends on the electromagnetic environment surrounding the emitter. The interaction of the emitter with strong local electromagnetic fields gives rise to an acceleration of the total decay rate (Purcell effect) which usually results in a broader emission line of the emitter, as well as an energy shift of the emission (Lamb shift). Plasmonic nanoantennas are versatile building blocks which localize light below the diffraction limit thanks to the extremely small effective mode volumes of localized surface plasmons, triggering out the possibility to tailor and exploit both the Purcell factor and the Lamb shift of nearby emitters, even reaching the strong coupling regime with polariton splitting in light emission. We theoretically describe light emission from a variety of nanoantenna-emitter configurations and reveal the potential of plasmonic nanogaps to tailor and engineering the Purcell factor and Lamb shift of light emitted from single nearby emitters, in agreement with experimental evidence.