Mainz 2026 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 29: Poster – Quantum Technologies I
Q 29.13: Poster
Tuesday, March 3, 2026, 17:00–19:00, Philo 2. OG
Towards Practical Quantum Networks: Atom-Photon entanglement over a metropolitan fiber link — •Maya Büki1, Pooja Malik2, Tobias Frank1, Marvin Scholz1, Florian Fertig2, Gianvito Chiarella1, Yiru Zhou2, Emanuele Distante4, Pau Farrera1,3, Harald Weinfurter1,2, and Gerhard Rempe1 — 1Max Planck Institute of Quantum Optics, Garching, Germany — 2Ludwig-Maximilians-University, Munich, Germany — 3Munich Center for Quantum Science and Technology (MCQST), Munich, Germany — 4University of Florence, Florence, Italy
Entanglement generation and distribution are key capabilities in order to build scalable quantum networks. While long-distance communication requires photons in the telecommunication band, interfacing with existing quantum infrastructure such as atomic quantum processors demands near-visible photons. Here, we demonstrate robust atom-photon entanglement over a distance of 23 km of fiber within the Munich metropolitan area. A single rubidium atom is entangled with a photon at 780 nm, which is converted to the telecom S-band and, after propagation over the long fiber, back-converted to its original wavelength. By using two tailor-made low-noise quantum frequency converters and mitigating polarization drifts and noise we achieve an end-to-end entanglement fidelity above 85%. This experiment demonstrates the integration of atomic quantum nodes with existing fiber networks and thus lays the foundation for practical long-distance quantum communication and information processing.
Keywords: Quantum Frequency Conversion; Quantum Network; Entanglement distribution; Quantum link