Cooling And Imaging A Single Trapped Cs Atom With A Quadrupole Transition*

We present three key advances in optical tweezer experiments: 1) Imaging lithium-6 atoms with near-ground state cooling using Λ-enhanced gray molasses, setting a new benchmark for low-loss imaging in neutral atoms. 2) A theoretical framework for various cooling mechanisms in optical tweezers, including gray molasses, sideband cooling, and polarization gradient cooling. 3) Cooling and imaging a single trapped Cs atom using the 685 nm 6S1/2–5D5/2 quadrupole transition, achieving 10 μK with background-free imaging. By shaping the excitation beam into a vortex mode, we transfer two units of angular momentum, enhancing quadrupole interactions and minimizing off-resonant scattering.

Looking ahead, we aim to create a 10-atom tweezer array with Cs and lithium (Li) atoms, exploring Feshbach resonances and magneto-association to form LiCs Feshbach molecules. We will also employ Stimulated Raman Adiabatic Passage (STIRAP) to achieve stable ground-state LiCs molecules, advancing ultracold chemistry and quantum control.