Dual-field and cross-field nonclassical light generation in a one-¹³³Cs atom cavity QED system

Abstract Nonclassical light fields exhibit unique quantum characteristics that not only expand the scope of optical research but also provide a solid foundation for advancements in quantum technologies. In this study, we investigate a system consisting of one- 133 Cs atom placed in a resonant cavity. Pumped by 459 nm laser light, the system generates cavity modes corresponding to the atomic 7 S 1/2 → 6 P 3/2 (1470 nm) and 7 S 1/2 → 6 P 1/2 (1359 nm) transitions, which are associated with the clock states of the cesium active optical clock. By analyzing the statistical and dynamical properties of the fields, we systematically explore the nonclassical behavior of the system under varying coupling strengths and cavity decay rates. We identify parameter regions where both individual fields and their cross-correlation exhibit nonclassicality, with the Cauchy–Schwarz (CS) violation coefficient R reaching a maximum of 13.9. This demonstrates the system’s ability to generate highly nonclassical photon pairs, enriching the repertoire of nonclassical light sources.