title: Simulating maximal quantum entanglement without communication.
abstract: It is known that all causal correlations between two parties which output each 1 bit, a and b, when receiving each 1 bit, x and y, can be expressed as convex combinations of local correlations (i.e., correlations that can be simulated with local random variables) and nonlocal correlations of the form a+b=xy mod 2. We show that a single instance of the latter elementary nonlocal correlation suffices to simulate exactly all possible projective measurements that can be performed on a maximally entangled state of two qubits, with no communication needed at all. This elementary nonlocal correlation thus defines some unit of nonlocality, which we call a nl bit.
authors.affiliation: Centre for Quantum Information and Communication, Ecole Polytechnique, CP 165/59, Université Libre de Bruxelles, Avenue F. D. Roosevelt 50, 1050 Brussels, Belgium.
authors.forename: N J
authors.initials: NJ
authors.lastname: Cerf
authors.forename: N
authors.initials: N
authors.lastname: Gisin
authors.forename: S
authors.initials: S
authors.lastname: Massar
authors.forename: S
authors.initials: S
authors.lastname: Popescu