We experimentally investigate the quantum-correlated twin beams generated through stimulated nondegenerate four-wave mixing in the double-lambda atomic system. A 2.5-dB noise reduction of intensity difference with 18.4-GHz frequency difference at the cesium $D_1$ line is observed in a Cs vapor cell. The quantitative theoretical analysis reveals the experimental difficulty in getting high quantum correlation in Cs atoms because of the large hyperfine splitting of the ground states. However, it is favorable for obtaining quantum correlation in a wide range of pump detunings and relative long lengths of vapor cells. This quantum correlation provides a potential resource for possible coherent interfaces between atomic and solid-state systems due to its wavelength at the Cs $D_1$ line which lies well within the wavelength regime of the exciton emission from InAs quantum dots.

• Received 22 September 2013

DOI:https://doi.org/10.1103/PhysRevA.89.033813