近日，印度玻色研究所的Pratapaditya Bej与Abhishek BanerjeeBose合作并取得一项新进展。经过不懈努力，他们对广义纠缠交换中的纠缠激活进行研究。相关研究成果已于2024年5月23日在国际知名学术期刊《物理评论A》上发表。
该研究团队深入探讨了涉及两个贝尔对和广义测量的广义纠缠交换过程中的纠缠激活现象。传统观念通常认为，对纠缠的测量是遥远双方之间建立纠缠关系的必要且充分条件。然而，在这项研究中，研究人员重新审视了测量算子在广义纠缠交换过程中对于纠缠产生的实际作用。他们特别关注了以最大纠缠双量子比特为初始态，并引入了广义测量的概念，深入研究了纠缠测量算子在建立纠缠关系时的必要性和充分性条件。
通过使用两个贝尔对——Alice和Bob共享的(1,2)对以及Bob和Charlie共享的(3,4)对——作为实验基础，他们成功证明了虽然纠缠测量对于建立纠缠关系是充分的，但它并非必不可少。通过顺序方法，如果Bob执行的初始测量无法建立纠缠，但在对第一次测量进行后处理后进行第二次测量，仍有可能成功建立纠缠。
研究人员确定了不同测量算子的特定标准，这些算子能够执行第二次测量以建立纠缠。这一发现凸显了通过测量组合在遥远的各方之间产生纠缠的可行性，揭示了量子网络中的纠缠分布。此外，他们通过说明性的例子展示了与单一测量相比，连续测量如何增强纠缠，强调了他们在增强纠缠方面的实际优势。此外，这项协议从二体量子比特态扩展到高维最大纠缠态，强调了其通用性和适用性。
附：英文原文
Title: Activation of entanglement in generalized entanglement swapping
Author: Pratapaditya Bej, Abhishek Banerjee
Issue&Volume: 2024/05/23
Abstract: We study entanglement activation in a generalized entanglement swapping process involving two Bell pairs and generalized measurements. The conventional understanding posits entangled measurements as both necessary and sufficient for establishing entanglement between distant parties. In this study, we reassess the role of measurement operators in entanglement generation within a generalized entanglement swapping process. We focus on maximally entangled two-qubit initial states and generalized measurements, investigating the necessity and sufficiency conditions for entangled measurement operators. By utilizing two Bell pairs, (1, 2) shared between Alice and Bob, and (3, 4) shared between Bob and Charlie, we demonstrate that while entangled measurements are sufficient, they are not indispensable for establishing entanglement between spatially separated observers. Through a sequential approach, if Bob performs an initial measurement which is not able to establish entanglement then followed by another measurement after postprocessing the first measurement it is possible to establish entanglement. We identify specific criteria for different measurement operators that enable the potential for performing a second measurement to establish entanglement. Our findings highlight the feasibility of generating entanglement between distant parties through a combination of measurements, shedding light on entanglement distribution in quantum networks. Additionally, we showcase through illustrative examples how successive measurements enhance entanglement compared to single measurements, underscoring the practical benefits of our approach in enhancing entanglement. Moreover, our protocol extends beyond bipartite qubit states to higher-dimensional maximally entangled states, emphasizing its versatility and applicability.
DOI: 10.1103/PhysRevA.109.052437
Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.052437
