Measurement-induced nonlocality in the W and Greenberger–Horne–Zeilinger superposition states*
Lin Qina), Bai Yan-Kuib), Ye Ming-Yonga)†, Lin Xiu-Mina)
       
Δ N = N ( ρ a | bc )–2 N ( ρ ab ) 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, Δ N will increase as cos (3 φ ) increases. There is Δ N ≥ 0 for any θ and φ that means the monogamy relation of MIN is always satisfied in the three-qubit W–GHZ state.