Unconventional photon blockade under the combined effects of optical parametric amplification and two-photon dissipation

Unconventional photon blockade (UPB) is an important quantum phenomenon that relies on the quantum interference effect. Here, we propose coupling an optical parametric amplifier (OPA) to a Kerr nonlinear single-mode cavity in a two-photon dissipation environment, enabling strong photon antibunching based on the UPB mechanism. The optimal conditions for achieving UPB are first derived analytically. The results are subsequently compared with the second-order correlation function derived from numerical simulations, and excellent agreement is observed. The findings show that UPB is enhanced without significantly reducing the mean photon number. This further demonstrates that the width of the UPB occurrence window increases with increasing OPA coefficient and driving laser intensity. Finally, theoretical analysis reveals the physical mechanism of UPB, showing that the Kerr medium is not the dominant factor for UPB generation in this system. Thus, our work offers valuable theoretical guidance for precisely controlling UPB and optimizing single-photon source performance.