Bipartite and tripartite output entanglement in 3-mode optomechanical   systems
  We provide analytic insight into the generation of stationary itinerant photon entanglement in a 3-mode optomechanical system. We identify the parameter regime of maximal entanglement, and show that strong entanglement is possible even for weak many-photon optomechanical couplings. We also show that strong tripartite entanglement is generated between the photonic and phononic output fields; unlike the bipartite photon-photon entanglement, this tripartite entanglement diverges as one approaches the boundary of system stability. 
Ying-Dan Wang, Stefano Chesi, Aashish A. Clerk
quant-ph cond-mat.mes-hall