UCLA

Trapped atomic ions are a multifaceted platform that can serve as a quantum information processor, precision measurement tool and sensor. However, in order to perform these experiments, the trapped ions need to be cooled substantially below room temperature. Doppler cooling has been a tremendous work horse in the ion trapping community. Hydrogen-like ions are good candidates because they have typically have a simple closed cycling transition that requires only a few lasers to Doppler cool. The \textsuperscript{2}S to \textsuperscript{2}P transition for these ions however typically lies in the UV to deep UV regime which makes buying a standard CW laser difficult as optical power here is hard to come by. Rather using a CW laser, which requires frequency stabilization and produces low optical power, this thesis explores how a mode-locked laser in the comb regime Doppler cools Yb ions. This thesis explores how a mode-locked laser is able to laser cool trapped ions and the consequences of using a broad spectrum light source. I will first give an overview of the architecture of our oblate Paul trap. Then I will discuss how a 10 picosecond optical pulse with a repetition rate of 80 MHz interacts with a 20 MHz linewidth \textsuperscript{2}S\(_{1/2}\) to \textsuperscript{2}P\(_{1/2}\) transition. Next I will go over our experiment involving ultrafast Ramsey experiment between the \textsuperscript{2}S\(_{1/2}\) and \textsuperscript{2}P\(_{1/2}\) states. Finally, I will present the results of these experiments.