Tunable continuous-variable steady entanglement via an atom in a microcavity

We consider a single two-level atom and exciton mode in a microcavity system. The second-order correlation function and the continuous-variable entanglement between the cavity and exciton mode are investigated. It is found that nonclassical (antibunching) effect and continuous-variable entangled light can be generated. One advantage of this system is that the generation of continuous-variable entanglement can be controlled by tuning the frequency of the pumping field.