Freiburg 2024 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 4: Hybrid Quantum Systems
Q 4.5: Talk
Monday, March 11, 2024, 12:00–12:15, HS 1199
Quantum repeater node with free-space coupled photons from trapped 40Ca+ ions — •Max Bergerhoff, Omar Elshehy, Stephan Kucera, Matthias Kreis, and Jürgen Eschner — Universität des Saarlandes, Experimentalphysik, 66123 Saarbrücken
The quantum repeater cell according to [1] is a fundamental building block for the realisation of large distance quantum networks. By dividing a transmission link in asynchronously driven segments it is possible to overcome the loss scaling of direct transmission. The advantage of this protocol has already been demonstrated with single atoms [2] in a cavity and single ions in a large cavity [3]. We report on the implementation of a quantum repeater cell with free-space coupled photons from two 40Ca+ ions in the same Paul trap as memories.
Atom-photon entanglement is generated asynchronously [4] by controlled emission of single photons from the individually addressed ions, and separate single-mode fiber coupling. Photon-photon entanglement is then generated by a Mølmer-Sørensen gate [5] on the ions. We discuss the probability and rate scaling due to the asynchronous sequence, as well as the fidelity of the final photon-photon state.
In this context the perspective of a new ion trap setup with integrated sub-mm cavity is discussed and its implementation status is presented.
[1] D. Luong et al., Appl. Phys. B 122, 96 (2016)
[2] S. Langenfeld et al., Phys. Rev. Lett. 126, 30506 (2021)
[3] V. Krutyanskiy et al., Phys. Rev. Lett. 130, 213601 (2023)
[4] M. Bock et al., Nat. Commun. 9, 1998 (2018)
[5] K. Mølmer and A. Sørensen, Phys. Rev. Lett 82, 1835-8 (1999)