PT-Symmetry-Enhanced Simultaneous Photon Blockade in a Dual-Cavity QED System

<p dir="ltr">We investigate how parity-time PT symmetry influences photon blockade in an atom-coupled dual-cavity quantum electrodynamics (QED) system, with a focus on distinguishing the underlying mechanisms. Statistical analysis demonstrates that photon blockade exhibits qualitatively distinct behaviors in the PT-symmetric and symmetry-broken phases, thereby providing a clear signature of the PT phase transition. In this PT-symmetric structure, the two-level atom provides the required nonlinearity, while cavity-cavity coupling under PT-symmetric control cooperatively enhances photon antibunching, leading to simultaneous photon blockade in both the gain and the lossy cavities. These phenomena are comprehensively analyzed using both analytical solutions of the Schrödinger equation and numerical simulations of the master equation. Comparisons with non-PT-symmetric configurations reveal that PT symmetry significantly enhances photon antibunching, mean photon number and promotes cooperative blockade behavior across both cavities. In contrast to conventional photon blockade schemes, our approach remains effective under weak coupling and weak nonlinearity conditions, offering a robust and tunable pathway toward realizing high-performance single-photon sources in non-Hermitian quantum systems.</p>