Mutual information of optical communication in phase conjugating Gaussian channels

TL;DR

This paper analyzes the mutual information in optical communication channels using phase conjugation and Gaussian detection, demonstrating significant performance improvements and the benefits of entanglement, regardless of channel gain.

Contribution

It introduces a phase-conjugated alphabet with joint Gaussian detection for optical communication, showing enhanced performance over standard methods and independence from channel gain.

Findings

Phase-conjugated alphabet with joint detection outperforms standard strategies.

Entanglement further improves communication performance.

Performance is independent of the channel's gain.

Abstract

In all practical communication channels, the code word consist of Gaussian states and the measurement strategy is often a Gaussian detector such as homodyning or heterodyning. In this paper we investigate the communication performance using a phase-conjugated alphabet and joint Gaussian detection in an phase-insensitive amplifying channel. We find that a communication scheme consisting of a phase-conjugated alphabet of coherent states and a joint detection strategy significantly outperforms a standard coherent-state strategy based in individual detection. Moreover, we show that the performance can be further enhanced by using entanglement and that the performance is completely independent on the gain of the phase-insensitively amplifying channel.