title: Do all pure entangled states violate Bell's inequalities for correlation functions?
abstract: Any pure entangled state of two particles violates a Bell inequality for two-particle correlation functions (Gisin's theorem). We show that there exist pure entangled N>2 qubit states that do not violate any Bell inequality for N particle correlation functions for experiments involving two dichotomic observables per local measuring station. We also find that Mermin-Ardehali-Belinskii-Klyshko inequalities may not always be optimal for refutation of local realistic description.
authors.affiliation: Instytut Fizyki Teoretycznej i Astrofizyki, Uniwersytet Gdański, PL-80-952 Gdańsk, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Zukowski
authors.forename: Caslav
authors.initials: C
authors.lastname: Brukner
authors.forename: Wiesław
authors.initials: W
authors.lastname: Laskowski
authors.forename: Marcin
authors.initials: M
authors.lastname: Wieśniak