Simulation of Quantum Correlation Functions is not Sufficient Resource to Describe Quantum Entanglement

Abstract

The Bell theorem expresses that quantum mechanics is not a local-realistic theory, which is often interpreted as nonlocality of the nature. This result has led to this belief that nonlocality and entanglement are the same resources. However, this belief has been critically challenged in the literature. Here, we reexamine the relation between nonlocality and entanglement in light of the Brassard-Cleve-Tapp (BCT) model, which was originally proposed for simulating quantum correlation of Bell's states by using shared random variables augmented by classical communications. We derive a new criterion for distinguishing quantum mechanics from the BCT model through suggesting an observable event based on the perfect correlations (anti-correlations) relation. In particular, we show that in the BCT model one can obtain equal outputs for two opposite input settings with the nonzero probability 0.284. Hence, in this sense we argue that the BCT model can give rise to an unphysical result. We also show the same problem with a nonlocal version of the BCT model.