Performance gain of displacement receiver with optimized prior probability

TL;DR

This paper demonstrates that optimizing prior probabilities in a displacement-based quantum receiver enhances mutual information and reduces code length for discriminating weak 3- and 4-PSK signals, surpassing shot-noise limits.

Contribution

It introduces prior probability optimization for asymmetric quantum receivers, improving discrimination performance and efficiency in quantum communication systems.

Findings

Optimized prior probabilities increase mutual information.

Sub-shot-noise discrimination achieved with optimized priors.

Shorter code lengths for given error rates with prior optimization.

Abstract

We numerically study the performance of the displacement based quantum receiver for the discrimination of weak 3- and 4-phase-shift keyed (PSK) coherent state signals. We show that due to the nontrivial asymmetry of the receiver structure, optimization of the prior probability increases the mutual information and achieves sub-shot-noise limit discrimination. Moreover, we estimate the cutoff rate for a 4-PSK signal and confirm that the prior probability optimization shortens the code length for a given decoding error criterion. Such consideration for the asymmetric channel matrix is essential in a study of the compassable quantum receiver.