Scalable Generation of Graph-State Entanglement through Realistic Linear   Optics
  We propose a scheme for efficient construction of graph states using realistic linear optics, imperfect photon source and single-photon detectors. For any many-body entanglement represented by tree graph states, we prove that the overall preparation and detection efficiency scales only polynomially with the size of the graph, no matter how small the efficiencies for the photon source and the detectors. 
T. P. Bodiya, L.-M. Duan