One-photon and two-photon blockades in a four-wave-mixing system embedded with an atom

In this paper, the photon blockade effect in a nondegenerate four-wave-mixing system embedded with a two-level atom has been studied. By using an analytical calculation and numerical analysis, we find that both one-photon and two-photon blockade effects could be realized in this system by adjusting the parameters of the system. That is, (i) when the four-wave-mixing interaction and the atom-cavity coupling strength are not equal, the system can realize a one-photon blockade; (ii) when they are consistent with each other, the system can realize a two-photon blockade. In addition, we also discuss the influence of different parameters on the photon blockade effect in detail. The results show that the system constructed in this paper not only could enhance the one-photon blockade effect decisively, but also could implement a two-photon blockade easily with a well-designed energy-level structure, and evidently the blockade effect depends on the parameters of the system. All the results may provide theoretical references for single-photon and multiphoton sources or devices in designing future experiments and practical applications.