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.

http://or.nsfc.gov.cn/bitstream/00001903-5/13990/1/1000007671010.pdf

Output entanglement in a four-level correlated emission laser

We investigate the continuous variable entanglement in a four-level atom according to the criterion proposed by Duan et al. [Phys. Rev. Lett. 84 (2000) 2722]. The atomic coherence is introduced using two external classical driving fields. We study the steady-state entanglement of the system in the presence of losses, concluding that the creation of entangled states can be achievable under certain conditions.

Ping Yun-Xia

Papers

Two-Mode Steady-State Entanglement in a Four-Level Atomic System