Freiburg 2024 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 31: Quantum Communication IV

Q 31.5: Talk

Wednesday, March 13, 2024, 12:00–12:15, HS 3219

Quantum communication protocols over the 14-km Saarbrücken fiber link — •Christian Haen, Stephan Kucera, Elena Arenskötter, Jonas Meiers, Tobias Bauer, and Jürgen Eschner — Universität des Saarlandes, Saarbrücken, Deutschland

Existing telecom-fiber infrastructure provides the basis for creating large scale quantum networks, potentially leading to the implementation of a quantum internet. The deployment of glassfibers for this purpose poses certain challenges, especially in urban areas, such as large disturbances in polarization.

We report on a 14-km long dark fiber link running across the Saarbrücken urban area, which we characterize for quantum networking by transmission of polarization- or time-bin-encoded photonic quantum bits. We stabilize the polarization of the fiber link and demonstrate quantum networking operations using a 40Ca+ single-ion quantum memory, an ion-resonant entangled photon-pair source, and quantum frequency conversion from the atomic wavelength to the telecom C-band. We realize dual-wavelength photon-photon entanglement, entanglement between an ion and a telecom photon, and teleportation of a qubit state from the ion onto a telecom photon transmitted over the link.

Keywords: quantum networking; glassfiber; calcium ion; photon-photon entanglement; teleportation