Beating the Standard Quantum Limit for Binary Constellations in the Presence of Phase Noise

TL;DR

This paper introduces a novel receiver design that surpasses the standard quantum limit for binary optical communication in phase noise environments by combining coherent displacement with photon number detection.

Contribution

It presents a new receiver strategy that interpolates between direct and homodyne detection, improving error rates in phase noise channels beyond existing quantum limits.

Findings

Receiver outperforms traditional methods in phase noise conditions

Achieves error rates below the standard quantum limit

Demonstrates practical implementation of advanced quantum measurement techniques

Abstract

Unconventional receivers enable reduction of error rates in optical communication systems below the standard quantum limit (SQL) by implementing discrimination strategies for constellation symbols that go beyond the canonical measurement of information-carrying quantities such as the intensity or quadratures of the electromagnetic field. An example of such a strategy is presented here for average-power constrained binary constellations propagating through a phase noise channel. The receiver, implementing a coherent displacement in the complex amplitude plane followed by photon number resolved detection, can be viewed as an interpolation between direct detection and homodyne detection.