Efficient multipartite entanglement purification with non-identical states

TL;DR

This paper introduces a highly efficient multipartite entanglement purification protocol for N-photon GHZ states with non-identical inputs, utilizing recycling strategies to improve fidelity and applicability in quantum communication networks.

Contribution

It presents a novel, general MEPP that reuses discarded items and compares two approaches, optimizing purification for non-identical input states.

Findings

Higher purification efficiency than previous methods.

Recycling discarded items enhances entanglement fidelity.

Suitable for long-distance quantum communication.

Abstract

We present an efficient and general multipartite entanglement purification protocol (MEPP) for N-photon systems in Greenberger-Horne-Zeilinger (GHZ) states with non-identical input states. As a branch of entanglement purification, besides the cases of successful purification, the recurrence MEPP actually has the reusable discarded items which are usually regarded as a failure. Our protocol contains two parts for bit-flip error correction. The first one is the conventional MEPP, corresponding successful cases. The second one includes two efficient approaches, recycling purification with entanglement link and direct residual entanglement purification, that can utilize discarded items. We also make a comparison between two approaches. Which method to use depends on initial input states, and in most cases the approach of direct residual purification is optimal for it not only may obtain a higher fidelity entangled state but also it does not require additional sophisticated links. In addition, for phase-flip errors, the discarded items still have available residual entanglement in the case of different input states. With these approaches, this MEPP has a higher efficiency than all previous MEPPs and it may have potential applications in the future long-distance quantum communications and networks.