New perspectives on quantum correlations

By performing well-chosen measurements on an entangled quantum state, distant observers can establish quantum non-local correlations. Gaining insight to such correlations is a challenging problem, important for both understanding the foundations of quantum mechanics and for developing applications in quantum information science. Here I present recent works progressing in this direction. In particular, after reviewing Bell's local model for quantum correlations, I will review Leggett's model, which focuses on individual properties. The incompatibility of both of these models with quantum predictions allows one to identify necessary conditions that any model aiming at reproducing the quantum correlations should satisfy. Remarkably, these constraints indicate a natural resource for simulating entanglement, namely the non-local box of Popescu and Rohrlich. I will conclude by reviewing such simulation models and discuss the insight they offer for understanding the relation between entanglement and non-locality. (C) 2009 Elsevier B.V. All rights reserved.