Engineering the impact of phonon dephasing on the coherence of a WSe$_{2}$ single-photon source via cavity quantum electrodynamics

Emitter dephasing is one of the key issues in the performance of solid-state single photon sources. Among the various sources of dephasing, acoustic phonons play a central role in adding decoherence to the single photon emission. Here, we demonstrate, that it is possible to tune and engineer the coherence of photons emitted from a single WSe$_2$ monolayer quantum dot via selectively coupling it to a spectral cavity resonance. We utilize an open cavity to demonstrate spectral enhancement, leveling and suppression of the highly asymmetric phonon sideband, finding excellent agreement with our microscopic theory. Most importantly, the impact of cavity tuning on the dephasing is directly assessed via optical interferometry, which clearly points out the capability to utilize light-matter coupling to steer and design dephasing and coherence of the emission properties of atomically thin crystals.