Are quantum correlations genuinely quantum?

TL;DR

This paper demonstrates that quantum correlations, such as those in the spin singlet, can be simulated using classical shared randomness without communication, challenging the notion that such correlations are inherently quantum.

Contribution

It shows that quantum correlations can be reproduced classically with shared randomness, and discusses implications for understanding quantum nonlocality and hidden-variable theories.

Findings

Classical shared randomness can simulate spin singlet correlations.

Reproducing correlations may imply a conspiracy if parties are conscious.

Detection efficiency reduction can mimic quantum correlations.

Abstract

It is shown that the probabilities for the spin singlet can be reproduced through classical resources, with no communication between the distant parties, by using merely shared (pseudo-)randomness. If the parties are conscious beings aware of both the hidden-variables and the random mechanism, then one has a conspiracy. If the parties are aware of only the random variables, they may be induced to believe that they are able to send instantaneous information to one another. It is also possible to reproduce the correlations at the price of reducing the detection efficiency. It is further demonstrated that the same probability decomposition could be realized through action-at-a-distance, provided it existed.