Passively stable distribution of polarisation entanglement over 192 km of deployed optical fibre

Sören Wengerowsky (Corresponding author), Siddarth Koduru Joshi, Fabian Steinlechner, Julien R. Zichi, Bo Liu, Thomas Scheidl, Sergiy M. Dobrovolskiy, René van der Molen, Johannes W. N. Los, Val Zwiller, Marijn A. M. Versteegh, Alberto Mura, Davide Calonico, Massimo Inguscio, Anton Zeilinger, André Xuereb, Rupert Ursin (Corresponding author)

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Quantum key distribution (QKD) based on entangled photon pairs holds the potential for repeater-based quantum networks connecting clients over long distance. We demonstrate long-distance entanglement distribution by means of polarisation-entangled photon pairs through two successive deployed 96 km-long telecommunications fibres in the same submarine cable. One photon of each pair was detected directly after the source, while the other travelled the fibre cable in both directions for a total distance of 192 km and attenuation of 48 dB. The observed two-photon Bell state exhibited a fidelity 85% $\pm$ 2% and was stable over several hours. We employed neither active stabilisation of the quantum state nor chromatic dispersion compensation for the fibre.
Original languageEnglish
Article number5
Number of pages5
Journalnpj Quantum Information
Issue number1
Publication statusPublished - 2020

Austrian Fields of Science 2012

  • 103025 Quantum mechanics
  • 103026 Quantum optics


  • quant-ph

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