Effect of dephasing on transient and steady-state entanglement in a quantum-beat laser

We study the role of dephasing on entanglement evolution in a two-photon quantum-beat laser. We rigorously derived the pertinent master equation by taking into account dephasing, spontaneous emission, and cavity losses. The dephasing rate, in general, is lager than the rates of other dissipation processes and might influence the realizable quantum properties of the cavity field. We investigate the extent to which the dephasing rate affects the transient as well as steady-state entanglement between the cavity modes. We show that the coherence induced by initial coherent superposition of atomic levels leads to transient as well as steady-state entanglement, which turns out to be susceptible to decoherence. However, the entanglement created via coherence induced by a strong laser field exists for only short times and is relatively robust against decoherence.