npj Quantum Information (Sep 2024)

Demonstration of quantum network protocols over a 14-km urban fiber link

  • Stephan Kucera,
  • Christian Haen,
  • Elena Arenskötter,
  • Tobias Bauer,
  • Jonas Meiers,
  • Marlon Schäfer,
  • Ross Boland,
  • Milad Yahyapour,
  • Maurice Lessing,
  • Ronald Holzwarth,
  • Christoph Becher,
  • Jürgen Eschner

DOI
https://doi.org/10.1038/s41534-024-00886-x
Journal volume & issue
Vol. 10, no. 1
pp. 1 – 11

Abstract

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Abstract We report on the implementation of quantum entanglement distribution and quantum state teleportation over a 14.4 km urban dark-fiber link, which is partially underground, partially overhead, and patched in several stations. We characterize the link for its use as a quantum channel and realize its active polarization stabilization. Using a type-II cavity-enhanced SPDC photon pair source, a 40Ca+ single-ion quantum memory, and quantum frequency conversion to the telecom C-band, we demonstrate photon-photon entanglement, ion-photon entanglement, and teleportation of a qubit state from the ion onto a remote telecom photon, all realized over the urban fiber link.