Measurement-induced nonlocality in the W and Greenberger–Horne–Zeilinger superposition states*
Lin Qina), Bai Yan-Kuib), Ye Ming-Yonga)†, Lin Xiu-Mina)
       
N ( ρ a | b ) of the two-qubit reduced state of the three-qubit W–GHZ state varies as a function of cos 2 θ and cos (3 φ ). For any fixed θ not equal to 0 or π /2, i.e., cos 2 θ ≠ 0 or 1, N ( ρ a | b ) will increase as cos (3 φ ) decreases.