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Light-matter entanglement over 50 km of optical fibre


on 16-07-2019

Ben Lanyon, Institute for Quantum Optics and Quantum Information and the University of Innsbruck

Date & time: Tuesday, July 16th, 15:00h
Location: Sala de formação avançada, 2nd floor of the Physics Department building, IST

Abstract:
When shared between remote locations, entanglement opens up fundamentally new capabilities for science and technology. Envisioned quantum networks use light to distribute entanglement between their remote matter-based quantum nodes. In this short talk, I will present our observation of entanglement between matter (a trapped ion) and light (a photon) over 50 km of optical fibre [1]: two orders of magnitude further than the state of the art and a practical distance to start building large-scale quantum networks. Our methods include an efficient source of ion-photon entanglement via cavity-QED techniques (0.5 probability on-demand fibre-coupled photon from the ion) and a single photon quantum frequency converter to the 1550 nm telecom C band (0.25 fibre-coupled device efficiency). Modestly optimising and duplicating our system could allow for 100 km-spaced ion-ion entanglement at rates over 1 Hz. Our results therefore show a path to entangling remote registers of quantum-logic capable trapped-ion qubits, and the optical atomic clock transitions that they contain, spaced by hundreds of kilometres.

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