Dissipative preparation of tripartite singlet state in coupled arrays of   cavities via quantum feedback control
  We propose an experimentally feasible scheme for dissipative preparation of tripartite entangled state with atoms separately trapped in an array of three coupled cavities. The combination of coherent driving fields and quantum-jump-based feedback control will drive the system into a non-equilibrium steady state, which has a nearly perfect overlap with the genuine three-atom singlet state. Different control strategies are investigated and the corresponding optimal parameters are confirmed. Moreover, the fidelity of target state is insensitive to detection inefficiencies, and it oversteps 90\% for a wide range of decoherence parameters as long as the single-atom cooperativity parameter $C\equiv g^2/(\gamma\kappa)>350$. 
X. Q. Shao, Z. H. Wang, H. D. Liu, and X. X. Yi
quant-ph