Hannover 2020 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 54: Posters: Quantum Optics and Photonics IV

Q 54.45: Poster

Thursday, March 12, 2020, 16:30–18:30, Empore Lichthof

Satellite- vs Ground-based quantum networks and the role of quantum repeaters — •Carlo Liorni, Hermann Kampermann, and Dagmar Bruß — Heinrich-Heine-Universität, Düsseldorf, Germany

Entanglement distribution over global distances (thousands of km) is a very daunting task. The exponential losses experienced during the propagation of light in optical fibres limit the achievable distances to ∼200 km in practice. A possible solution consists in the use of quantum repeaters, based on entanglement swapping or quantum error correction. Satellite-based optical links can be very advantageous in this case, as the losses scale only quadratically with the distance, when atmospheric effects are small. In this work, we analyse a scheme that combines these two ingredients, ground-based quantum repeaters and satellite-based links in the downlink configuration, in order to achieve long distance entanglement distribution. The performance of this repeater chain is assessed in terms of the secret key rate achievable by the BB-84 cryptographic protocol, that depends on both the entanglement distribution rate and the quality of the final shared state. The comparison with the fibre-based implementation shows that the satellite-mediated scheme performs better in almost every situation. Finally, we propose an augmented scheme that takes advantage of orbiting quantum repeater stations in order to achieve higher key rates, reliability and flexibility. The integration between satellite-based links and ground repeater networks can be envisaged to represent the backbone of the future Quantum Internet.