Rate limits in quantum networks with lossy repeaters

Abstract

The derivation of ultimate limits to communication over certain quantum repeater networks have provided extremely valuable benchmarks for assessing near-term quantum communication protocols. However, these bounds are usually derived in the limit of ideal devices and leave questions about the performance of practical implementations unanswered. To address this challenge, we quantify how the presence of loss in repeater stations affect the maximum attainable rates for quantum communication over linear repeater chains and more complex quantum networks. Extending the framework of node splitting, we model the loss introduced at the repeater stations and then prove the corresponding limits. In the linear chain scenario we show that, by increasing the number of repeater stations, the maximum rate cannot overcome a quantity which solely depends on the loss of a single station. We introduce a way of adapting the standard machinery for obtaining bounds to this realistic scenario. The difference is that whilst ultimate limits for any strategy can be derived given a fixed channel, when the repeaters introduce additional decoherence, then the effective overall channel is itself a function of the chosen repeater strategy (e.g., one-way versus two-way classical communication). Classes of repeater strategies can be analysed using additional modelling and the subsequent bounds can be interpreted as the optimal rate within that class.

arXiv comment13 pages, 5 figures, replaced with final version

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Cited by in corpus (5)

• Complex Quantum Networks: a Topical Review
• Multi-User Entanglement Distribution in Quantum Networks Using Multipath Routing
• Entanglement Distribution in Quantum Repeater with Purification and Optimized Buffer Time
• ReQuSim: Faithfully simulating near-term quantum repeaters
• End-to-End Capacities of Imperfect-Repeater Quantum Networks