Tight multipartite Bell's inequalities involving many measurement settings

Abstract

We derive tight Bell's inequalities for N>2 observers involving more than two alternative measurement settings. We give a necessary and sufficient condition for a general quantum state to violate the new inequalities. The inequalities are violated by some classes of states, for which all standard Bell's inequalities with two measurement settings per observer are satisfied.

published version generalizing results of quant-ph/0303187 and quant-ph/0311182