Strong Photon Blockade Mediated by Optical Stark Shift in a Single-Atom–Cavity System

Realizing single-photon sources plays an essential role in quantum information science. The key step for generating a single photon is to attain strong photon blockade, based on either strong energy-spectrum anharmonicity or quantum interference to eliminate two-photon excitation. However, the strong coupling in a high-finesse cavity that is needed for these mechanisms is still a challenge. In this work, strong photon antibunching with a large cavity photon number is predicted, by combining the optical Stark shift with anharmonicity and quantum interference beyond the strong-coupling regime. This proposal suggests exciting opportunities for applications in $e.g.$ quantum networks.