Narrow Results

The generation and evolution of entanglement and squeezing for the two-mode fields are discussed in a cascade three-level atomic system. Two photons of a strong external pump field induce atomic coherence between the top and bottom levels. The dynamics of this system in the presence of cavity losses is studied. It is shown that entanglement and squeezing between the two modes increase initially, then decrease and eventually disappear. The periods of them are extended with the increasing of the pump field intensity. The effects of the cavity losses on squeezing and entanglement are also discussed.

The continuous-variable (CV) entanglement of the output fields is investigated in a four-level correlated emission laser system. The atomic coherence is introduced using two external classical driving fields. Based on the input–output theory, it is shown that the output entanglement and the entangled photons of the system can be achievable under certain conditions. Moreover, it is found that the two-mode entanglement has a close relation with the intensities of two external driving fields.