Entanglement Enhancement Via Collective CPT in Bichromatically Driven Three-Level Atoms

We investigate the generation of two-mode entangled light from cooperative three-level cascade emitters driven by two lasers inside an optical cavity. It is found that through collective coherent population trapping (CPT) to prepare the atomic states close to the coherent superposition state |1>-|3>√2 of the top and ground levels, the entanglement and mean photon number of the entangled light can be significantly enhanced in comparison to the case of independent atoms.