The past decades have seen rapid advances in our ability to probe and control atoms. The ability to bring atoms into the ultracold regime has opened up many applications, ranging from creating the most precise clocks to quantum simulation of condensed matter systems. Compared to atoms, molecules have a much richer internal structure. This gives rise to qualitatively new features that are desirable for an even wider range of applications such as quantum information processing and precision measurement.
Although quantum control of molecules is much more challenging because of the many additional internal degrees of freedom, there has been rapid progress in the past few years. Coherent assembly of ultracold atoms are now routinely used to create ultracold molecular samples. An orthogonal approach that provides access to a much wider class of molecules is direct laser cooling. This approach has also seen great success, starting with the first molecular magneto-optical traps a few years back.
In this talk, I will describe some of our recent results in direct laser cooling and trapping of CaF molecules. We have developed techniques to laser-cool optically trapped molecules well below the Doppler limit, and have demonstrated a vastly improved detection method that makes possible non-destructive high-fidelity imaging of trapped single molecules. Very recently, using these methods, we have loaded and imaged single CaF molecules trapped in optical tweezers. In the future, by rearranging these traps, defect-free tweezer arrays of ultracold molecules can be created, providing a bottom-up approach in assembling interacting many-body systems molecule-by-molecule. This approach is also extendable to many other molecules, including larger polyatomic ones, which could be ideally suited for molecular qubits or for searches of beyond-Standard-Model physics.