Hannover 2010 – scientific programme
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SYFC: Symposium Variations of Fundamental Constants: Theory and Experiment
SYFC 2: Variations of Fundamental Constants II
SYFC 2.4: Talk
Monday, March 8, 2010, 17:45–18:00, A 001
Towards Direct Frequency Comb Spectroscopy of Metal Ions — •Boerge Hemmerling, Daniel Nigg, Ivan V. Sherstov, and Piet O. Schmidt — QUEST Inst. for Experimental Quantum Metrology, PTB Braunschweig & Leibniz University of Hannover, Germany
The possible variation of fundamental constants is a highly debated subject. Laboratory experiments that compare ultra-precise clocks to probe the variation of the fine-structure constant are within their errors compatible with α/α ∼ 0. However, experiments on astronomical time scales that compare quasar absorption spectra with today’s spectra of metal ions yield contradictory results reaching from no variation to Δ α/α ∼ 10−5. The latter observations are amongst other obstacles limited by inaccurate spectroscopy data on certain transition lines in complex ions such as Ca+, Ti+ and Fe+ [1].
We plan to investigate these ions by sympathetically cooling them via magnesium ions in a linear Paul trap to the motional ground state. By employing well-developed quantum logic techniques [2], we plan to elude difficulties, such as state preparation and detection in these multi-level systems. Furthermore, a frequency comb will be used as a spectroscopy probe to cover the few 10 nm wide band of interesting transition lines. We will present the latest experimental results of our ground state cooling scheme where we compare pulsed and cw approaches to reach the ground state of the harmonic trap.
[1] J. C. Berengut et al., arXiv:physics/0408017 (2006)
[2] P. O. Schmidt et al., Science 309, 749-752 (2005)