LAUSR

Narrow bright or dark resonances associated with electromagnetically induced transparency play a key role in enhancing photon-photon interactions. The schemes realized to date relied on the existence of long-lived atomic states with strong van der Waals interactions. Here, we show that by placing an atomically thin semiconductor with ultrafast radiative decay rate inside a microcavity, it is possible to obtain extremely narrow dark or bright resonances in transmission. While breaking of translational invariance sets a limit on the width of the dark resonance width, it is possible to obtain a narrow bright resonance that is much narrower than the cavity and bare exciton decay rates and is protected against disorder by tuning the cavity away from the excitonic transition. Resonant excitation of this bright resonance yields strong photon antibunching even in the limit where the interaction strength is arbitrarily smaller than the non-Markovian disorder broadening and the radiative linewidth of the bare exciton. Our findings suggest that atomically thin semiconductors which exhibit large exciton-cavity coupling and small nonradiative line broadening could pave the way for the realization of strongly interacting photonic systems in the solid state.