Controlling the dynamics of a coupled atom-cavity system by pure dephasing

The influence of pure dephasing on the dynamics of the coupling between a two-level atom and a cavity mode is systematically addressed. We have derived an effective atom-cavity coupling rate that is shown to be a key parameter in the physics of the problem, allowing to generalize the known expression for the Purcell factor to the case of broad emitters, and to define strategies to optimize the performances of broad emitterbased single-photon sources. Moreover, pure dephasing is shown to be able to restore lasing in presence of detuning, a further demonstration that decoherence can be seen as a fundamental resource in solid-state cavity quantum electrodynamics, offering appealing perspectives in the context of advanced nanophotonic devices. We propose experimental strategies to develop a versatile device that can be operated either as a single-photon source or as a laser, based on the control by decoherence of the coupling between a single quantum dot and a solid-state cavity.