Photon blockade in giant atom-coupled triple-cavity system

The photon blockade effects in a system consisting of an artificial giant atom coupled to three cavities are investigated. By solving the Schrödinger equation, we have obtained the steady-state probability amplitudes of the system and derived the analytical expressions for the equal-time second-order correlation function. Based on these analytical expressions, the optimal conditions for the photon blockade under different driving conditions are derived in detail. We first examine the energy spectrum and transition pathways for the single-photon and two-photon excitations under the case of weak driving the cavity mode, and then investigate the photon statistical properties . It is demonstrated that the optimal conventional photon blockade can be achieved by selecting appropriate driving detunings, characterized by the equaltime second-order correlation function of g⁽²⁾ (0) ≈ 10-3.4. Remarkably, we observe that both cavities of the system exhibit photon blockade effects robust against the weak driving. It also can be found that the photon blockade phenomenon becomes more pronounced while maintaining its robustness to the weak driving with the increase of the coupling strength between the artificial giant atom and cavities. Furthermore, we consider the case of simultaneously driving both the artificial giant atom and cavity modes. The unique multi-point coupling characteristics of the artificial giant atom provide additional transition pathways for photons, allowing us to exploit the resulting quantum interference to further enhance photon blockade. When the system satisfies both the optimal parametric conditions for the conventional and unconventional blockade effects, one cavity exhibits exceptional photon blockade with g⁽²⁾ (0) ≈ 10-6.5. This research significantly relaxes the stringent parameter requirements for the experimental realization of single-photon sources and provides a theoretical support for improving their quality, which is crucial for achieving high-performance single-photon source.