Quantum superadditivity in linear optics networks: sending bits via multiple access Gaussian channels

TL;DR

This paper demonstrates that quantum resources can violate classical additivity laws in Gaussian multiple access channels, enabling superadditivity effects in information transmission.

Contribution

It introduces two feasible quantum Gaussian MAC schemes showing how quantum resources enable superadditivity, surpassing classical capacity limits.

Findings

Quantum resources enable superadditivity in Gaussian MACs

Classical additivity law can be violated with quantum resources

Two feasible experimental schemes demonstrated

Abstract

We study classical capacity regions of quantum Gaussian multiple access channels (MAC). In classical variants of such channels, whilst some capacity superadditivity-type effects such as the so called {\it water filling effect} may be achieved, a fundamental classical additivity law can still be identified, {\it viz.} adding resources to one sender is never advantageous to other senders in sending their respective information to the receiver. Here, we show that quantum resources allows violation of this law, by providing two illustrative schemes of experimentally feasible Gaussian MACs.