Freiburg 2019 – scientific programme
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FM: Fall Meeting
FM 18: Quantum Networks: Interfaces & Hybrid Systems
FM 18.2: Talk
Monday, September 23, 2019, 17:00–17:15, 1015
Towards a Suburban Quantum Network Link — •Tim van Leent1, Robert Garthoff1, Kai Redeker1, Matthias Bock2, Wei Zhang1, Wenjamin Rosenfeld1,3, Christoph Becher2, and Harald Weinfurter1,3 — 1Fakultät für Physik, Ludwig-Maximilians-Universität, 80799 Munich, Germany — 2Fachrichtung Physik, Universität des Saarlandes, 66123 Saarbrücken, Germany — 3Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
Quantum repeaters will allow scalable quantum networks, which is essential for large scale quantum communication and distributed quantum computing. Yet, still missing on the road towards a quantum repeater, is to achieve entanglement between quantum memories over long distances.
Here we present results on observing atom-photon entanglement between a Rubidium 87 atom and a telecom photon over 10 km optical fiber with a fidelity of 85%. For this purpose, we use quantum frequency conversion, where the spontaneously emitted photon at 780 nm is mixed with a strong pump field at 1600 nm inside a nonlinear waveguide crystal in a Sagnac-type interferometer configuration [1,2]. The atomic coherence time is extended to hundreds of µs by suppressing magnetic field fluctuations with a guiding field. Installing frequency conversion for the second atom will allow to generate atom-atom entanglement on a suburban scale [3].
[1] M. Bock et al., Nat. Comm. 9, 1998 (2018)
[2] R. Ikuta et al., Nat. Comm. 9, 1997 (2018)
[3] W. Rosenfeld et al., Phys. Rev. Lett. 119, 010402 (2017)