Non-Markovian Spontaneous Emission Dynamics of a Quantum Emitter Near a Transition-Metal Dichalcogenide Layer

Abstract

We investigate the spontaneous emission dynamics of a two-level quantum emitter near a transition-metal dichalcogenide layer, specifically, a tungsten disulfide (WS<inline-formula><tex-math notation= LaTeX >$_{2}$</tex-math></inline-formula>) layer. The optical response of the WS<inline-formula><tex-math notation= LaTeX >$_{2}$</tex-math></inline-formula> layer is obtained by electromagnetic calculations using parameters by experimental data. We find that depending on the distance between the quantum emitter, and the WS<inline-formula><tex-math notation= LaTeX >$_2$</tex-math></inline-formula> layer the spontaneous decay can be enhanced up to <inline-formula><tex-math notation= LaTeX >$10^4$</tex-math></inline-formula> compared with its free-space value for an emitter with transition dipole moment oriented perpendicular or tangential to the layer. We also perform quantum dynamical calculations, which indicate that the emitter s spontaneous emission dynamics changes from Markovian to weakly non-Markovian to clearly non-Markovian, featuring decaying population oscillations, as the coupling grows from relatively weak to strong, depending on the distance of the emitter to the layer, and the emitter s free-space decay rate. For quantum emitters with fast free-space decay times placed at close distances to the WS<inline-formula><tex-math notation= LaTeX >$_2$</tex-math></inline-formula> layer, the ultrastrong coupling regime can be reached, and we find that a significant amount of the initial population of the quantum emitter can remain trapped in it. We also quantify non-Markovianity using different measures. Similar results can also be obtained for other transition-metal dichalcogenide layers, like a tungsten diselenide (WSe<inline-formula><tex-math notation= LaTeX >$_2$</tex-math></inline-formula>) layer.