Entanglement recovery by reversing the effect of noise in quantum repeater

TL;DR

This paper introduces a probabilistic reversing operation that recovers entanglement lost due to noise in quantum repeaters, significantly improving entanglement distribution robustness.

Contribution

It presents a novel heralded protocol for reversing noise effects on entanglement, compatible with existing techniques and applicable to current quantum repeater architectures.

Findings

Entanglement can be recovered even under strong noise conditions.

The protocol is effective in two-way and one-way repeater models.

It enables robust entanglement distribution in practical quantum networks.

Abstract

We propose a method to directly recover the degree of entanglement distributed by entanglement swapping in the presence of noise. Our approach introduces a reversing operation that probabilistically undoes the effect of amplitude damping or photon loss on a single entangled pair, enabling heralded recovery of entanglement. We demonstrate that entanglement can be substantially recovered even under strong noise, including parameter regimes where the distributed entanglement would otherwise vanish due to entanglement sudden death. We analyze the effectiveness of the protocol in two representative repeater models, i.e.,~two-way and one-way architectures and identify the optimal reversing strategy. Due to its heralded and single-copy nature, our protocol is readily compatible with other entanglement recovery techniques such as entanglement purification and distillation. Our work provides a practical and experimentally feasible way toward robust entanglement distribution in current and near-term quantum repeater architectures.