Enhanced photon antibunching via interference effects in a Δ configuration

Abstract

Photon antibunching based on a single two-level atom strongly coupled to a single-mode optical cavity has been demonstrated in experiments. Here, we put forward an improved version of such an antibunching by introducing a pump field and a microwave field in the coupled atom-cavity system to form both a three-level $\mathrm{\ensuremath{\Delta}}$-type transition and closed-loop coupling. Via calculating the zero-time-delay second-order correlation function ${g}^{(2)}(0)$ of the single-mode cavity field, we find that a complete photon blockade, namely, ${g}^{(2)}(0)=0$, can be well achieved without detuning the driving and cavity resonance. In addition, it is clearly shown that this strong photon antibunching effect appears in the weak-coupling regime of light-atom interactions. The enhanced photon antibunching is ascribed to quantum interference between the two transition paths from the three-level $\mathrm{\ensuremath{\Delta}}$ atom weakly coupled to the three involved fields (cavity, pump, and microwave). Our proposal is useful for the single-photon generation by photon blockade, which has applications in quantum information processing.