Stable molecules trapped at ultracold temperatures are rich systems for precision studies of quantum chemistry and fundamental physics.
In this talk, I will describe experiments with strontium dimers in an optical lattice. Adapting techniques from optical atomic clocks, we expose the peculiar asymptotic physics of these molecules, highlighting the fundamental difference between weakly bound molecules and pairs of atoms at long range. We exploit the physics of subradiance to enhance spectroscopic precision, perform coherent manipulation, and uncover nonradiative molecular decay. For the first time, we quantitatively study the strengths of allowed and forbidden multipole transitions in molecules. Measurements of anomalous magnetic shifts reveal the quantum phases of mixed wavefunctions produced by the breakdown of the Born-Oppenheimer picture. Finally, I will describe a novel thermometry technique well suited for molecules, and discuss prospects for future work made possible by cold and ultracold molecules.