Generation of Three-Qubit Entangled W-State by Nonlinear Optical State   Truncation
  We propose an alternative scheme to generate W state via optical state truncation using quantum scissors. In particular, these states may be generated through three-mode optical state truncation in a Kerr nonlinear coupler. The more general three-qubit state may be also produced if the system is driven by external classical fields. 
R S Said, M R B Wahiddin, and B A Umarov