We develop a protocol for entanglement generation in the quantum internet that allows a repeater node to use n-qubit Greenberger-Horne-Zeilinger (GHZ) projective measurements that can fuse n successfully entangled links, i.e., two-qubit entangled Bell pairs shared across n network edges, incident at that node. Implementing n-fusion, for n ≥ 3, is in principle not much harder than 2-fusions (Bell-basis measurements) in solid-state qubit memories. If we allow even 3-fusions at the nodes, we find—by developing a connection to a modified version of the site-bond percolation problem—that despite lossy (hence probabilistic) link-level entanglement generation, and probabilistic success of the fusion measurements at nodes, one can generate entanglement between end parties Alice and Bob at a rate that stays constant as the distance between them increases. We prove that this powerful network property is not possible to attain with any quantum networking protocol built with Bell measurements and multiplexing alone. We also design a two-party quantum key distribution protocol that converts the entangled states shared between two nodes into a shared secret, at a key generation rate that is independent of the distance between the two parties.

我们开发了一种用于在量子互联网中产生纠缠的协议，该协议允许中继器节点使用n -qubit Greenberger-Horne-Zeilinger (GHZ) 投影测量，可以融合n 个成功的纠缠链接，即跨n共享的两个量子比特纠缠贝尔对网络边缘，事件在该节点。实现n -fusion，对于n ≥ 3，原则上并不比固态量子比特存储器中的 2 融合（贝尔基测量）难多少。如果我们甚至允许在节点处进行 3 次融合，我们会发现——通过建立与站点键渗透问题的修改版本的连接——尽管有损（因此是概率的）链路级纠缠生成，并且融合测量的概率成功在节点上，可以在端方 Alice 和 Bob 之间产生纠缠，其速率随着它们之间距离的增加而保持不变。我们证明，仅使用贝尔测量和多路复用构建的任何量子网络协议都无法实现这种强大的网络特性。我们还设计了一个两方量子密钥分发协议，将两个节点之间共享的纠缠状态转换为共享秘密，