1998/04/20 by N. Gisin, H. Bechmann-Pasquinucci · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1016/s0375-9601(98)00516-7
published as Phys.Lett. A246 (1998) 1-6 · 8 pages, no figure
arxiv created 1998/04/20 · arxiv updated 2009/12/01
First, we present a Bell type inequality for n qubits, assuming that m out of the n qubits are independent. Quantum mechanics violates this inequality by a ratio that increases exponentially with m. Hence an experiment on n qubits violating of this inequality sets a lower bound on the number m of entangled qubits. Next, we propose a definition of maximally entangled states of n qubits. For this purpose we study 5 different criteria. Four of these criteria are found compatible. For any number n of qubits, they determine an orthogonal basis consisting of maximally entangled states generalizing the Bell states.