Linking ions with photons.

Florian R. Ong, Klemens Schüppert, Pierre Jobez +8 more

The realization of a quantum network requires linking distant nodes via a quantum channel. To realize this link, it seems natural to use single photons to transmit or to share the quantum state of a static qubit. In this direction, a trapped ion in cavity has already been used to perform ion-photon entanglement [1] and ion-to-photon state mapping [2].

Matthias Keller

Stephan Kucera, Christian Haen, Elena Arenskötter +9 more

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 $^{40}$Ca$^{+}$ 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.

Stephan Kucera, Christian Haen, Elena Arenskötter +9 more

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 40 Ca + 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.