Optical tweezer array of fully quantum-state-controlled polar molecules

Ultracold polar molecules, compared to their atomic counterparts, possess rich internal structures and exhibit long-range dipole-dipole interactions that render them useful for many applications such as quantum simulation of matter, quantum computation and precision measurements. At the heart of many of these proposals is the ability to trap and control ultracold molecules at the individual particle level. Recently, we have demonstrated this capability, assembling single rovibrational ground state NaCs molecules in optical tweezers starting from single ultracold atoms. This bottom-up approach utilizes laser cooling and trapping techniques of ultracold atoms and has enabled us to achieve full quantum state control, including all the internal and external degrees of freedom, on individually trapped molecules in an array. Furthermore, we have characterized the rotational transition of the ground state molecules, which is important for many exciting possibilities that can harness the rich properties of ultracold molecules.