title: Fundamental rate-loss trade-off for the quantum internet.
abstract: The quantum internet holds promise for achieving quantum communication-such as quantum teleportation and quantum key distribution (QKD)-freely between any clients all over the globe, as well as for the simulation of the evolution of quantum many-body systems. The most primitive function of the quantum internet is to provide quantum entanglement or a secret key to two points efficiently, by using intermediate nodes connected by optical channels with each other. Here we derive a fundamental rate-loss trade-off for a quantum internet protocol, by generalizing the Takeoka-Guha-Wilde bound to be applicable to any network topology. This trade-off has essentially no scaling gap with the quantum communication efficiencies of protocols known to be indispensable to long-distance quantum communication, such as intercity QKD and quantum repeaters. Our result-putting a practical but general limitation on the quantum internet-enables us to grasp the potential of the future quantum internet.
authors.affiliation: NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Azuma
authors.affiliation: Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Mizutani
authors.affiliation: Center for Quantum Information and Quantum Control (CQIQC), University of Toronto, Toronto, Ontario M5S 3G4, Canada.|Department of Physics, University of Toronto, 60 St. George St., Toronto, Ontario M5S 1A7, Canada.|The Edward S. Rogers Sr. Department of Electrical &Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
authors.forename: Hoi-Kwong
authors.initials: HK
authors.lastname: Lo