Increased atom-cavity coupling through cooling-induced atomic reorganization

The strong coupling of atoms to optical cavities can improve optical lattice clocks as the cavity enables metrologically useful collective atomic entanglement and high-fidelity measurement. To this end, it is necessary to cool the ensemble to suppress motional broadening, and advantageous to maximize and homogenize the atom-cavity coupling. We demonstrate resolved Raman sideband cooling via the cavity as a method that can simultaneously achieve both goals. In 200 ms of Raman sideband cooling, we cool Yb 171 atoms to an average vibration number 〈 n x 〉 = 0.23 ( 7 ) in the tightly binding direction, resulting in 93 % optical π -pulse fidelity on the clock transition S 0 1 → P 0 3 . During cooling, the atoms self-organize into locations with maximal atom-cavity coupling, which will improve quantum metrology applications.