Börge Hemmerling has graduated from the Gottfried Wilhelm Leibniz Universität Hannover. The Titel of his dissertation; "Towards Direct Frequency Comb Spectroscopy Using Quantum Logic".
Here a small excerpt from the dissertation:
Astrophysical investigations searching for a time-variation of fundamental constants strongly depend on accurate laboratory wavelength of a number of transitions of various complex ions, such as Ti+ and Fe+, which, up to present, have resisted precision laser spectroscopy. In this thesis, a versatile setup that lays the basis to study such ions with a frequency comb as a spectroscopy source and theoretical calculations on the expected spectroscopy signal are presented.