Fundamental rate-loss trade-off for the quantum internet

TLDR

The quantum internet promises global quantum communication and simulation of many‑body systems by efficiently distributing entanglement or secret keys through intermediate nodes linked by optical channels. We aim to derive a fundamental rate‑loss trade‑off for quantum internet protocols. We generalize the Takeoka‑Guha‑Wilde bound so that it applies to any network topology. The resulting trade‑off matches the efficiencies of indispensable long‑distance protocols such as intercity QKD and quantum repeaters, offering a practical limit that clarifies the future quantum internet’s potential.

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.