Introduction

Abstract

This thesis describes work performed over the past 6 years to establish the state of the art in manipulation and quantum control of ultracold molecules. The molecules I discuss are very weakly bound (and therefore very large) ⁸⁸Sr₂ dimers, produced via photoassociation of ultracold strontium atoms followed by spontaneous decay to a stable ground state. We study their rovibrational structure from several different perspectives, including determinations of binding energies; linear, quadratic, and higher order Zeeman shifts; transition strengths between bound states; and lifetimes of narrow subradiant states. The physical intuition gained in these experiments applies generally to weakly bound diatomic molecules, and suggests extensive applications in precision measurement and metrology. In addition, I present a detailed analysis of the thermally broadened spectroscopic lineshape of molecules in a non-magic optical lattice trap, showing how such lineshapes can be used to directly determine the temperature of atoms or molecules in situ, addressing a long-standing problem in ultracold physics. Finally, I discuss the measurement of photofragment angular distributions produced by photodissociation, leading to an exploration of quantum-state-resolved ultracold chemistry.