Freiburg 2019 – wissenschaftliches Programm
FM 27.4: Invited Talk
Dienstag, 24. September 2019, 12:30–13:00, Audi Max
Towards quantum networks based on single trapped atoms — •Wenjamin Rosenfeld — Ludwig-Maximilians-Universität, München — Max-Planck-Institut für Quantenoptik, Garching
Quantum networks hold promise for enabling secure communication and distributed quantum computing. In this context, single trapped atoms represent a mature platform featuring a high level of control of internal and external degrees of freedom, long coherence times and reliable coupling to photonic channels. These features recently enabled distribution of entanglement between single atoms over macroscopic distances  and certification of its properties allowing for applications in an elementary quantum network link .
Current work is focused on extending the distance of entanglement distribution. Since the ground-state optical transitions in atoms are typically in the visible or near-infrared regime, for efficient long-distance transport of photons over optical fibers quantum frequency conversion into telecom wavelength range is required. Based on a nonlinear conversion process, this method was already successfully demonstrated for trapped ions  and is now being developed for the neutral atom platform. First measurements show a promising capability for distributing entanglement over few tens of kilometers - a realistic distance for implementing an elementary link of a quantum repeater.
 W. Rosenfeld et al., Phys. Rev. Lett., 119, 010402 (2017).
 J.-D. Bancal et al., arXiv:1812.09117 [quant-ph] (2018).
 M. Bock et al., Nature Communications 9, 1998 (2018)