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QI: Fachverband Quanteninformation
QI 36: Poster – Quantum Information (joint session QI/Q)
QI 36.16: Poster
Donnerstag, 13. März 2025, 17:00–19:00, Tent
Atom-Photon entanglement across a metropolitan network — •Maya Büki1, Tobias Frank1, Marvin Scholz1, Gianvito Chiarella1, Pau Farrera1, Pooja Malik2, Yiru Zhou2, Florian Fertig2, Harald Weinfurter1,2, and Gerhard Rempe1 — 1Max-Planck-Institute of Quantum Optics, Garching, Germany — 2Ludwig-Maximilians-University, Munich, Germany
Building a scalable quantum network is a key challenge in quantum information science. A critical step in this endeavor is the establishment of robust quantum links capable of transmitting entangled quantum states over long distances. Here, we present the successful demonstration of atom-photon entanglement over a distance of 23 km, spanning the Munich metropolitan area. Within this scope, we can efficiently entangle the spin states of Rubidium (Rb) atoms with optical polarization qubits. This experiment addresses critical challenges, including transmission losses through optical fiber, polarisation drifts and noise. By leveraging quantum frequency conversion from λRb = 780 nm to the telecom band and tailored filtering techniques, we successfully preserved entanglement fidelity over the link. By converting back the wavelength of the photon to 780 nm it might be possible to write the qubit information onto a heralded quantum memory consisting of a Rubidium atom inside two crossed optical fiber cavities [1]. With this goal in mind we made a first but decisive step towards a real world quantum network link within the Munich metropolitan area.
[1] M. Brekenfeld et al. Nat. Phys. 16, 647 - 651 (2020)
Keywords: Quantum Frequency Conversion; Quantum Network; Entanglement distribution; Quantum link