论文标题

随机党纠缠蒸馏中本地运营和古典交流(LOCC)的圆形复杂性

The Round Complexity of Local Operations and Classical Communication (LOCC) in Random-Party Entanglement Distillation

论文作者

Liu, Guangkuo, George, Ian, Chitambar, Eric

论文摘要

用于分布式量子信息处理的强大操作范式涉及通过本地操作和经典交流(LOCC)操纵前共享的纠缠。给定任务的LOCC圆形复杂性描述了完成任务需要多少轮古典交流。尽管有一些结果将单轮与两轮协议区分开,但对于更高的圆形复杂性知之甚少。在本文中,我们重新审视了一次性随机党纠缠蒸馏的任务,以突出一些有趣的LOCC圆形复杂性的特征。我们首先表明,对于三个量子位的随机派对,最佳协议中所需的通信回合数取决于所使用的纠缠措施。对于相同的固定状态,一些纠缠措施只需要两轮即可最大化,而其他纠缠措施则需要无限的回合。在此过程中,我们构建了一系列LOCC仪器,需要无限的回合才能实施。然后,我们证明了LOCC圆号上的明确紧密下限,这是蒸馏成功概率的函数。我们的计算表明,在圆形复杂性方面,Fortescue和LO的原始W-State随机蒸馏协议本质上是最佳的。

A powerful operational paradigm for distributed quantum information processing involves manipulating pre-shared entanglement by local operations and classical communication (LOCC). The LOCC round complexity of a given task describes how many rounds of classical communication are needed to complete the task. Despite some results separating one-round versus two-round protocols, very little is known about higher round complexities. In this paper, we revisit the task of one-shot random-party entanglement distillation as a way to highlight some interesting features of LOCC round complexity. We first show that for random-party distillation in three qubits, the number of communication rounds needed in an optimal protocol depends on the entanglement measure used; for the same fixed state some entanglement measures need only two rounds to maximize whereas others need an unbounded number of rounds. In doing so, we construct a family of LOCC instruments that require an unbounded number of rounds to implement. We then prove explicit tight lower bounds on the LOCC round number as a function of distillation success probability. Our calculations show that the original W-state random distillation protocol by Fortescue and Lo is essentially optimal in terms of round complexity.

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