Role of syndrome information on a one-way quantum repeater using teleportation-based error correction

TL;DR

This paper explores how utilizing syndrome measurement outcomes in a quantum repeater scheme can enhance secret key rates, potentially surpassing known bounds for direct transmission over lossy channels.

Contribution

It introduces a method to incorporate syndrome information into quantum repeater protocols, improving secret key rate calculations and performance.

Findings

Optimized syndrome information increases secret key rates.

Key rates can surpass the PLOB bound for direct transmission.

Incorporating syndrome data enhances quantum communication efficiency.

Abstract

We investigate a quantum repeater scheme for quantum key distribution based on the work by Muralidharan et al., Phys. Rev. Lett. 112, 250501 (2014). Our scheme extends that work by making use of error syndrome measurement outcomes available at the repeater stations. We show how to calculate the secret key rates for the case of optimizing the syndrome information, while the known key rate is based on a scenario of coarse-graining the syndrome information. We show that these key rates can surpass the Pirandola-Laurenza-Ottaviani-Banchi bound on secret key rates of direct transmission over lossy bosonic channels.