Engineering W-type steady states for three atoms via dissipation in an   optical cavity
  We propose a scheme for the dissipative preparation of W-type entangled steady-states of three atoms trapped in an optical cavity. The scheme is based on the competition between the decay processes into and out of the target state. By suitable choice of system parameters, we resolve the whole evolution process and employ the effective operator formalism to engineer four independent decay processes, so that the target state becomes the stationary state of the quantum system. The scheme requires neither the preparation of definite initial states nor the precise control of system parameters and preparation time. 
Xin-Yu Chen, Li-Tuo Shen, Zhen-Biao Yang, Huai-Zhi Wu and Mei-Feng   Chen
quant-ph