Entanglement of nanomechanical oscillators and two-mode fields induced   by atomic coherence
  We propose a scheme via three-level cascade atoms to entangle two optomechanical oscillators as well as two-mode fields. We show that two movable mirrors and two-mode fields can be entangled even for bad cavity limit. We also study entanglement of the output two-mode fields in frequency domain. The results show that the frequency of the mirror oscillation and the injected atomic coherence affect the output entanglement of the two-mode fields. 
Ling Zhou, Yan Han, Jietai Jing, Weigping Zhang
quant-ph