Computation-aided classical-quantum multiple access to boost network communication speeds

TL;DR

This paper demonstrates that leveraging computation properties in quantum multiple access channels, especially in network topologies, can significantly enhance communication speeds, achieving maximum rates in certain boson channels.

Contribution

It introduces a novel approach to quantum network communication by using computation properties to optimize achievable rates based on network topology, surpassing conventional methods.

Findings

Achieves maximum single-user capacity in boson coherent channels with binary modulation.

Different detection methods can realize the maximum rate, including quantum and classical techniques.

Provides practical applications, including cryptographic protocols.

Abstract

A multiple access channel (MAC) consists of multiple senders simultaneously transmitting their messages to a single receiver. For the classical-quantum case (cq-MAC), achievable rates are known assuming that all the messages are decoded, a common assumption in quantum network design. However, such a conventional design approach ignores the global network structure, i.e., the network topology. When a cq-MAC is given as a part of quantum network communication, this work shows that computation properties can be used to boost communication speeds with code design dependently on the network topology. We quantify achievable quantum communication rates of codes with computation property for a two-sender cq-MAC. When the two-sender cq-MAC is a boson coherent channel with binary discrete modulation, we show that it achieves the maximum possible communication rate (the single-user capacity), which cannot be achieved with conventional design. Further, such a rate can be achieved by different detection methods: quantum (with and without quantum memory), on-off photon counting and homodyne (each at different photon power). Finally, we describe two practical applications, one of which cryptographic.