Simulating maximal quantum entanglement without communication.
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.
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Centre for Quantum Information and Communication, Ecole Polytechnique, CP 165/59, Université Libre de Bruxelles, Avenue F. D. Roosevelt 50, 1050 Brussels, Belgium.
Gisin
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Massar
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Popescu
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