Secure communication over generalised quantum multiple access channels

TL;DR

This paper analyzes the security of quantum multiple-access channels, providing a rate region formula, a superdense coding protocol based on GHZ states, and security proofs against quantum attacks.

Contribution

It introduces a secure communication protocol for two senders over quantum multiple-access channels using GHZ states and analyzes its security and capacity.

Findings

Derived the achievable rate region for secure communication

Proposed a GHZ-based superdense coding protocol

Proved security against general quantum attacks

Abstract

We investigate the security of generalized quantum multiple-access channels. We provide the formula for the achievable rate region of secure communication in the scenario of two senders and a single receiver. We explicitly specify a protocol for secure communication in this scenario, which employs superdense coding. The protocol is based on the distribution of a tripartite GHZ state. It allows for both symmetric and asymmetric key distribution whereby one of the senders can have twice the capacity of the other sender. We prove the security of the protocol against general quantum attacks, analyze different strategies of the eavesdropper and compute the key rate for a range of noisy quantum channels.