Decay suppression of spontaneous emission of a single emitter in a high-Q cavity at exceptional points

Abstract

The exceptional point (EP) is a non-Hermitian degeneracy of an open quantum system, where the behavior of the system is of a fundamental distinguishing nature. Within the framework of exact quantum electrodynamics in dispersing and absorbing media, we study the strong-coupling regime of a single emitter–high-Q cavity system in the case where two cavity modes and the corresponding resonant frequencies coalesce at an EP. We demonstrate a substantial increase in the effective decay time of the spontaneous emission in the EP case. We show that this effect is directly related to the peculiar spectral response of the electromagnetic field at the EP. We apply the concept to the case of a microdisk cavity perturbed by nanoparticle scatterers, where the spontaneous emission decay suppression can be related to the parameters of the real system.