Impact of detuning and dephasing on a laser-corrected subnatural-linewidth single-photon source

Abstract

The elastic scattering peak of a resonantly driven two-level system has been argued to provide narrow-linewidth antibunched photons. Although independent measurements of spectral width on the one hand and antibunching, on the other hand, do seem to show that this is the case, a joint measurement reveals that only one or the other of these attributes can be realised in the direct emission. We discuss a scheme which interferes the emission with a laser to produce simultaneously single photons of subnatural linewidth. In particular, we consider the effect of dephasing and of the detuning between the driving laser and/or the detector with the emitter. We find that our scheme brings such considerable improvement as compared to the standard schemes as to make it the best single-photon source in terms of all-order multi-photon suppression by several orders of magnitudes. While the scheme is particularly fragile to dephasing, its superiority holds even for subnatural-linewidth emission down to a third of the radiative lifetime.