Arbitrarily little knowledge can give a quantum advantage for nonlocal tasks

TL;DR

This paper demonstrates that even minimal local knowledge enables quantum strategies to outperform classical ones in nonlocal tasks, revealing new insights into the role of information in quantum advantage.

Contribution

It shows that small amounts of local input knowledge can unlock quantum advantages in nonlocal computation, challenging previous assumptions.

Findings

Quantum advantage appears with minimal local input knowledge.

Classical correlations cannot outperform quantum strategies without input knowledge.

Insights into the role of information in quantum nonlocality.

Abstract

It has previously been shown that quantum nonlocality offers no benefit over classical correlations for performing a distributed task known as nonlocal computation. This is where separated parties must compute the value of a function without individually learning anything about the inputs. We show that giving the parties some knowledge of the inputs, however small, is sufficient to unlock the power of quantum mechanics to out-perform classical mechanics. This role of information held locally gives new insight into the general question of when quantum nonlocality gives an advantage over classical physics. Our results also reveal a novel feature of the nonlocality embodied in the celebrated task of Clauser, Horne, Shimony and Holt.