Hamburg 2009 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 35: Quanteneffekte: QED / Interferenz und Korrelationen I

Q 35.4: Talk

Wednesday, March 4, 2009, 14:45–15:00, VMP 6 HS-E

Cavity QED with Cold Ion Coulomb Crystals — •Magnus Albert, Joan Marler, Aurelien Dantan, Peter Herskind, and Michael Drewsen — QUANTOP, Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark

Clouds of cold ions are an interesting alternative system to a single atom/ion for studying CQED effects. When trapped and cooled below a critical temperature, these ions form a spatially ordered state, referred to as an ion Coulomb crystal. In our setup, we trap and cool ⁴⁰Ca⁺ ions in sufficient number to access the so-called strong collective coupling regime, where the collective coupling, g√N, exceeds both the dipole decay rate, γ, and the cavity decay rate, κ, without using an extremely high finesse cavity[1]. We will present the first signals of collective strong coupling, in this system - most dramatically manifested via the vacuum Rabi splitting. Finally, we measure the temporal coherence of collective Zeeman sub-states in the 3d³D_3/2-level by induced Lamor precession. The measured coherence times are of the order of the best reported values for single ions in equivalent magnetic field sensitive states[2]. Our results make the system a promissing candidate for the realisation of various quantum information devices, including quantum repeaters and quantum memories.

[1] P. Herskind, A. Dantan, M.B. Langkilde-Lausen, A. Mortensen, J. L. Sørensen and M. Drewsen, Appl. Phys. B 93, 373 (2008)

[2] P. Herskind, A. Dantan, J. Marler, M. Albert and M. Drewsen, Realisation of Collective Strong Coupling with Ion Coulomb Crystals in an Optical Cavity, submitted