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Q: Fachverband Quantenoptik und Photonik
Q 60: Quantum Information II
Q 60.18: Poster
Donnerstag, 17. März 2022, 16:30–18:30, P
Towards long Coherence Times for a Single-Atom Quantum Memory — •Florian Fertig1,2, Tim van Leent1,2, Yiru Zhou1,2, Pooja Malik1,2, Anastasia Reinl1,2, Robert Garthoff1,2, Wei Zhang1,2, and Harald Weinfurter1,2,3 — 1Fakultät für Physik, Ludwig-Maximilians-Universität, Munich, Germany — 2Munich Center for Quantum Science and Technology (MCQST), Munich, Germany — 3Max-Planck-Institut für Quantenoptik, Garching, Germany
For large scale quantum networks, long coherence times are crucial to distribute high quality entanglement over long distances. Our experiment consists of two nodes employing optically trapped single-atoms as quantum memories including quantum frequency conversion to the low loss telecom S band. The two atoms are entangled using an entanglement swapping protocol. For fiber links with a length of multiple kilometers, the quality is limited by the coherence time of the atomic states [1].
Here, we report on the implementation of a new trap geometry mitigating any decoherence effects (T2 ≈ 330 µs) stemming from the optical dipole trap (ODT). These effects emerge from longitudinal components of the electric field that arise due to the tightly focused (w0 < 2 µm) ODT beam. For this, we overlap the single ODT beam with another counterpropagating one to set up a standing-wave geometry. As the effective magnetic field of the second beam has an opposite sign, perfect overlap will cancel the effective magnetic field and increase the coherence time to the millisecond scale.
[1] T. van Leent et al., arXiv:2111.15526 (2021)