Inducing tunable conventional photon blockade and two-photon blockade in a second-order nonlinear system with two-level atoms

We have achieved a conventional photon blockade and two-photon blockade in a second-order nonlinear system with a two-level atom embedded in a high-frequency cavity. The physical mechanisms behind the implementation of both types of photon blockade are explained, and analytical conditions for achieving a conventional photon blockade are derived, which are consistent with the numerical solutions of the master equation in the steady-state limit. By appropriately setting the system parameters, we can achieve simultaneous conventional photon blockade in the high-frequency cavity and two-photon blockade in the low-frequency cavity. The effects of driving factors and environmental temperature on photon blockade are analyzed. The adjustability of the coupling coefficient between the high-frequency cavity and the atom, as well as the nonlinear coupling coefficient between different nanocavities, is discussed in the context of implementing conventional photon blockades. The tunability of these coupling coefficients may significantly reduce the experimental complexity of implementing the system.