Optimal entanglement distribution policies in homogeneous repeater chains with cutoffs

Abstract We study the limits of bipartite entanglement distribution using a chain of quantum repeaters that have quantum memories. To generate end-to-end entanglement, each node can attempt the generation of an entangled link with a neighbor, or perform an entanglement swapping measurement. A maximu...

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Bibliographic Details
Main Authors: Álvaro G. Iñesta, Gayane Vardoyan, Lara Scavuzzo, Stephanie Wehner
Format: Article
Language:English
Published: Nature Portfolio 2023-05-01
Series:npj Quantum Information
Online Access:https://doi.org/10.1038/s41534-023-00713-9
Description
Summary:Abstract We study the limits of bipartite entanglement distribution using a chain of quantum repeaters that have quantum memories. To generate end-to-end entanglement, each node can attempt the generation of an entangled link with a neighbor, or perform an entanglement swapping measurement. A maximum storage time, known as cutoff, is enforced on the memories to ensure high-quality entanglement. Nodes follow a policy that determines when to perform each operation. Global-knowledge policies take into account all the information about the entanglement already produced. Here, we find global-knowledge policies that minimize the expected time to produce end-to-end entanglement. Our methods are based on Markov decision processes and value and policy iteration. We compare optimal policies to a policy in which nodes only use local information. We find that the advantage in expected delivery time provided by an optimal global-knowledge policy increases with increasing number of nodes and decreasing probability of successful swapping.
ISSN:2056-6387