Enhancement of Photon Blockade in Cavity‐Magnon Systems via Coherent Feedback

This paper proposes a novel scheme to enhance the photon blockade effect in a cavity‐magnon system via coherent feedback loops. The system comprises a microwave cavity, a coherent feedback loop, and a yttrium iron garnet sphere. The cavity mode is coupled to the magnon mode via magnetic dipole interaction and is driven by both a two‐photon driving field and a weak pump field. The statistical properties of photons are characterized through the second‐order correlation function. Research findings indicate that coherent feedback significantly enhances the photon blockade effect, with the underlying physical mechanism being the effective reduction of the average two‐photon number. After introducing the two‐photon driving field, the optimal driving intensity and phase conditions for achieving photon blockade through analytical calculations are obtained. Under these optimal parameters, the proposed scheme demonstrates a low reflection coefficient, thereby ensuring excellent experimental feasibility and flexible controllability. This study offers new insights into the design of tunable single‐photon sources and establishes a novel research platform based on coherent feedback control for realizing photon blockade.