Motional ground-state cooling of single atoms in state-dependent optical tweezers*

In recent years, ensembles of atoms individually trapped in optical tweezer arrays have proven to be excellent systems for quantum computing and quantum simulation. An important aspect is to cool atoms in the tweezers to the motional ground state, which is typically achieved via resolved sideband cooling. Those schemes, however, require a magic trapping condition for the atomic states involved in the cooling, which sets strong constraints for applications. Here, I report on our studies of a ground-state cooling scheme overcoming this constraint. Applicable for scenarios where the ground state of the cooling transition is stronger trapped than the excited state, the scheme relies on a laser frequency chirp sequentially addressing red sideband transitions. At the example of 88Sr atoms, we report ground-state populations compatible with recent experiments in magic tweezers. The scheme also induces light-assisted collisions, which are key to the assembly of large atom arrays. Our work enriches the toolbox for tweezer-based quantum technology, also enabling applications for tweezer-trapped molecules and ions that are incompatible with resolved sideband cooling conditions.