Local Hidden Variable Theories for Quantum States

While all bipartite pure entangled states violate some Bell inequality, the relationship between entanglement and non-locality for mixed quantum states is not well understood. We introduce a simple and efficient algorithmic approach for the problem of constructing local hidden variable theories for quantum states. The method is based on constructing a so-called (s_a,s_b)-symmetric quasi-extension of the quantum state that gives rise to a local hidden variable model with s_a and s_b settings for the observers Alice and Bob respectively