title: Bell's theorem for general N-qubit states.
abstract: We derive a single general Bell inequality which is a sufficient and necessary condition for the correlation function for N particles to be describable in a local and realistic picture, for the case in which measurements on each particle can be chosen between two arbitrary dichotomic observables. We also derive a necessary and sufficient condition for an arbitrary N-qubit mixed state to violate this inequality. This condition is a generalization and reformulation of the Horodecki family condition for two qubits.
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