Continuous and Reversible Electrical Tuning of Fluorescent Decay Rate via Fano Resonance

Decay rate of an atomic or molecular dipole depends on the local density of optical states (LDOS) -- Purcell effect -- which can significantly be enhanced near a dielectric-core metal-shell nanoparticle (CSNP). On top of that, an auxiliary quantum object (QO) can introduce a Fano transparency in the plasmonic spectrum of the CSNP. Here, we show that an auxiliary QO, located at the hotspot of the CSNP, can modify the LDOS, hence the decay rate of an excited dipole. Moreover, by controlling the resonance of the auxiliary QO via an applied voltage, one can continuously and reversibly tune both the radiative and nonradiative decay rates of the dipole up to 2 orders-of-magnitude. This phenomenon emerges as an invaluable tool to implement in integrated quantum technologies, enabling realization of on-demand entanglement/single-photon sources, controlled execution of quantum gates and electrical-control of superradiant-like phase transitions. It also bears potential for application in super-resolution microscopy and surface-enhanced Raman spectroscopy (SERS).