Quantum Internet Gets a Boost

Researchers from the University of Innsbruck have made significant progress in building a quantum repeater, a device that can transmit quantum information over long distances. Quantum networks connect quantum processors or sensors with each other, enabling tap-proof communication and high-performance distributed sensor networks. However, the likelihood of photons being lost increases dramatically over long distances. The quantum repeater features light-matter entanglement sources and memories to create entanglement in independent network links that are connected between them by a so-called entanglement swap to finally distribute entanglement over long distances. The researchers have now built the core parts of a quantum repeater, a fully functioning network node made with two single matter systems enabling entanglement creation with a photon at the standard frequency of the telecommunications network and entanglement swapping operations. They demonstrated the transfer of quantum information over a 50-kilometer-long optical fiber, with the quantum repeater placed exactly halfway between starting and end point. The researchers were also able to calculate which improvements of this design would be necessary to make transmission over 800 kilometers possible which would allow to connect Innsbruck to Vienna.