Proposal for enhanced photon blockade in parity-time-symmetric coupled microcavities

Abstract

Recent demonstrations of parity-time- $(\mathcal{PT}$-) symmetric structure have exhibited the great potential of this system for tailoring the light-matter interaction and developing a wide range of robust quantum devices. Here we explore the second-order photon correlations in a $\mathcal{PT}$-symmetric system consisting of a passive nonlinear cavity coupled to an active cavity via optical tunneling. It is shown numerically that strong photon antibunching including perfect photon blockade can be obtained efficiently even if the Kerr nonlinearity strength, the photon-tunneling strength, and the driving strength are smaller than the cavity decay rate. The physical mechanism underlying photon blockade originally comes from the dynamical enhancement of intracavity nonlinearity by the effect of supermode field localization in the $\mathcal{PT}$-symmetric arrangement. The results obtained provide insight into the crossover between the photon blockade and $\mathcal{PT}$-symmetric theory. Such controllable photon antibunching may find applications in the generation of high-quality single-photon sources.