Quantum communication complexity advantage implies violation of a Bell inequality

TLDR: It is proved that any large advantage over the best known classical strategy makes use of Bell nonlocal correlations, providing the missing link to the fundamental equivalence between Bell nonlocality and quantum advantage.

Abstract: We obtain a general connection between a large quantum advantage in communication complexity and Bell nonlocality. We show that given any protocol offering a sufficiently large quantum advantage in communication complexity, there exists a way of obtaining measurement statistics that violate some Bell inequality. Our main tool is port-based teleportation. If the gap between quantum and classical communication complexity can grow arbitrarily large, the ratio of the quantum value to the classical value of the Bell quantity becomes unbounded with the increase in the number of inputs and outputs.