Enhancing atom-cavity coupling through Raman sideband cooling

Andrew J. Kerman

J.V. Thompson, Tobias Tiecke, Vladan Vuletić +1 more

Galina A. Nemova

Chi Shu, Simone Colombo, Zeyang Li +4 more

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. Published by the American Physical Society 2024

Alban Urvoy, Jiazhong Hu, Zachary Vendeiro +2 more

René Reimann, Wolfgang Alt, Tobias Macha +4 more

We experimentally realize an enhanced Raman control scheme for neutral atoms that features an intrinsic suppression of the two-photon carrier transition, but retains the sidebands which couple to the external degrees of freedom of the trapped atoms. This is achieved by trapping the atom at the node of a blue detuned standing wave dipole trap, that acts as one field for the two-photon Raman coupling. The improved ratio between cooling and heating processes in this configuration enables a five times lower fundamental temperature limit for resolved sideband cooling. We apply this method to perform Raman cooling to the two-dimensional vibrational ground state and to coherently manipulate the atomic motion. The presented scheme requires minimal additional resources and can be applied to experiments with challenging optical access, as we demonstrate by our implementation for atoms strongly coupled to an optical cavity.