Quantum Nonlocality of N-qubit W states
  An experimental setup for testing quantum nonlocality of N qubits is proposed. This method is a generalization of the optical setup proposed by Banaszek and Wodkiewicz [1]. The quantum nonlocality of N qubits can be obtained through its violation of N-qubit Bell inequalities. The correlation function measured in the experiment is described by the Wigner function. The effect of inefficient detector is also considered. 
Chunfeng Wu, Jing-Ling Chen, L. C. Kwek and C. H. Oh