In this project we will investigate and implement methods to circumvent limitations in accuracy and stability using both an operational strontium lattice clock and a more flexible setup with ultracold calcium. With these optical clocks we will investigate fundamental questions of the temporal and spatial stability of e.g. the fine structure constant α and its potential couplings to dark matter. Specifically tailored motional quantum states shall be used to identify and minimize motion-related clock uncertainties. To address limitations from the linewidth of the interrogation laser, which is in fact limiting the stability of most ion and neutral atom clocks, we will in parallel investigate an active optical frequency source based on super-fluorescence on a narrow clock transition.