Yan Pei-Shun, Zhou Lan, Zhong Wei, Sheng Yu-Bo
Opt Express. 2021 Mar 15;29(6):9363-9384. doi: 10.1364/OE.420348.
Entanglement purification is used to distill high quality entangled states from several noisy low quality entangled states, and it plays a key role in quantum repeater. The measurement-based entanglement purification protocol (MB-EPP) does not require local two-qubit gates or single-particle measurements on the noisy pairs and may offer significant advantages compared with the gate-based EPPs. We present an alternative MB-EPP in linear optics. Subsequently, we provide a detailed analysis on the realization of this MB-EPP using spontaneous parametric down conversion (SPDC) sources. By delicately designing the optical circuits, the double-pair emission noise caused by SPDC sources can be eliminated automatically. Combined with suitable quantum memory and entanglement swapping, this MB-EPP may have application potential in the implementation of a practical measurement-based quantum repeater.
纠缠纯化用于从多个有噪声的低质量纠缠态中提取高质量的纠缠态，它在量子中继器中起着关键作用。基于测量的纠缠纯化协议（MB-EPP）不需要对有噪声的量子对进行局部两比特门操作或单粒子测量，与基于门的纠缠纯化协议相比可能具有显著优势。我们提出了一种线性光学中的替代MB-EPP。随后，我们对使用自发参量下转换（SPDC）源实现此MB-EPP进行了详细分析。通过精心设计光学电路，可以自动消除由SPDC源引起的双对发射噪声。结合合适的量子存储器和纠缠交换，这种MB-EPP在实际的基于测量的量子中继器实现中可能具有应用潜力。
