Entanglement-assisted capacity regions and protocol designs for quantum multiple-access channels

TL;DR

This paper determines the entanglement-assisted capacity regions for quantum multiple-access channels, demonstrating practical receiver designs that significantly outperform non-entangled schemes, with implications for quantum communication networks.

Contribution

It provides the first explicit solution for the entanglement-assisted capacity region of quantum multiple-access channels and proposes practical receiver protocols utilizing two-mode squeezed vacuum states.

Findings

EA capacity region is larger than unassisted capacity.

Practical receiver designs achieve up to 82% rate advantage.

Results extend to EA quantum communication at half the classical rates.

Abstract

We solve the entanglement-assisted (EA) classical capacity region of quantum multiple-access channels with an arbitrary number of senders. As an example, we consider the bosonic thermal-loss multiple-access channel and solve the one-shot capacity region enabled by an entanglement source composed of sender-receiver pairwise two-mode squeezed vacuum states. The EA capacity region is strictly larger than the capacity region without entanglement-assistance. With two-mode squeezed vacuum states as the source and phase modulation as the encoding, we also design practical receiver protocols to realize the entanglement advantages. Four practical receiver designs, based on optical parametric amplifiers, are given and analyzed. In the parameter region of a large noise background, the receivers can enable a simultaneous rate advantage of 82.0% for each sender. Due to teleportation and superdense coding, our results for EA classical communication can be directly extended to EA quantum communication at half of the rates. Our work provides a unique and practical network communication scenario where entanglement can be beneficial.