Quantum Repeater Protocol using Quantum Error Correction for Distillation

TL;DR

This paper introduces a quantum repeater protocol that employs quantum error correction for deterministic entanglement distillation, optimizing the routing of Werner states in quantum networks to improve fidelity and efficiency.

Contribution

It presents a novel quantum error correction-based method for entanglement distillation in quantum repeaters, utilizing global link-state knowledge for optimal scheduling.

Findings

Low-rate codes achieve higher fidelity end-to-end states.

High-rate codes produce more end-to-end states with lower fidelity.

Memory and computation requirements increase with code rate.

Abstract

Bell-state measurement (BSM) on entangled states shared between quantum repeaters is the fundamental operation used to route entanglement in quantum networks. Performing BSMs on Werner states shared between repeaters leads to exponential decay in the fidelity of the end-to-end Werner state with the number of repeaters, necessitating entanglement distillation. In this work, we use quantum error correcting codes for deterministic entanglement distillation to route Werner states on a chain of repeaters. To maximize the end-to-end distillable entanglement, we utilize global link-state knowledge to determine the optimal policy for scheduling distillation and BSMs at the repeaters. We observe that low-rate codes produce high-fidelity end-to-end states owing to their excellent error-correcting capability, whereas high-rate codes yield a larger number of end-to-end states but of lower fidelity. The number of quantum memories used at repeaters increases with the code rate as well as the classical computation time of the decoder.