Quantum advantages in multiparty communication

TL;DR

This paper demonstrates that quantum communication can outperform classical limits in a multiparty scenario with two senders and one receiver, even without entanglement or input choices, highlighting a clear quantum advantage.

Contribution

The authors explicitly characterize classical bounds under dimension and distinguishability constraints and show quantum communication exceeds these bounds without preshared entanglement.

Findings

Quantum communication surpasses classical bounds in the studied scenario.

Explicit classical correlation bounds are derived under given constraints.

Semidefinite hierarchy tools are adapted for the multiparty setting.

Abstract

We investigate two senders and one receiver multiparty communication scenario. Following Phys.Rev.A83, 062112 and arXiv : 2506.07699, we study multiparty communication bounded by dimension and distinguishability. We provide an explicit characterization of the classical correlations achievable under these constraints. We then demonstrate that quantum communication systematically exceeds these classical limits, even in the absence of preshared entanglement and without any input choice for the receiver. Furthermore, we implement semidefinite hierarchy tools tailored to the two-sender, one-receiver setting for both types of constraints considered. Our results reveal a clear quantum advantage in multiparty communication under those restrictions.