Aggregating quantum repeaters for the quantum internet

TL;DR

This paper proposes a protocol for aggregating quantum repeaters in a network to enhance quantum communication, analyzing its performance relative to fundamental capacity bounds and exploring its optimality in the context of quantum information theory.

Contribution

It introduces a universal protocol for combining quantum repeaters in networks and examines its performance against theoretical capacity limits.

Findings

The protocol operates in parallel over the network.

Performance bounds are established based on quantum capacity limits.

The protocol's optimality relates to additivity and capacity gap questions.

Abstract

The quantum internet holds promise for performing quantum communication, such as quantum teleportation and quantum key distribution, freely between any parties all over the globe. For such a quantum internet protocol, a general fundamental upper bound on the performance has been derived [K. Azuma, A. Mizutani, and H.-K. Lo, arXiv:1601.02933]. Here we consider its converse problem. In particular, we present a protocol constructible from any given quantum network, which is based on running quantum repeater schemes in parallel over the network. The performance of this protocol and the upper bound restrict the quantum capacity and the private capacity over the network from both sides. The optimality of the protocol is related to fundamental problems such as additivity questions for quantum channels and questions on the existence of a gap between quantum and private capacities.