Precision spectroscopy with 40Ca+ ions in a Paul trap

This thesis reports on experiments with trapped Ca+ ions related to the field of precision spectroscopy and quantum information processing. For the absolute frequency measurement of the 4s2S1/2-3d2 D5/2 clock transition of a single, laser-cooled 40Ca+ ion, an optical frequency comb was referenced to the transportable Cs atomic fountain clock of LNE-SYRTE and the frequency of an ultra-stable laser exciting this transition was measured. After correction for systematic shifts an absolute transition frequency of fCa+=411042129776393.2 (1.0) Hz is obtained, corresponding to 2.4*10-15 relative uncertainty. The main research field of our group is quantum information processing, therefore it is obvious to use the tools and techniques related to this topic and apply them to high-resolution spectroscopy. As a first realization, the quadrupole moment of the 3d2D5/2 state was measured to be θ(3d, 5/2) =1.82(1) ea20 with Ramsey-type experiments of especially designed Bell states. While entanglement leads to enhanced signal-to-noise ratios, it is not an essential ingredient for this kind of method. The measurement result obtained with classically correlated but un-entangled states confirms the measured value previously obtained with maximally entangled states. (author)