This thesis describes how the rich internal degrees of freedom of molecules can be exploited to construct the first “clock” based on ultracold molecules, rather than atoms. By holding the molecules in an optical lattice trap, the vibrational clock is engineered to have a high oscillation quality factor, facilitating the full characterization of frequency shifts affecting the clock at the hertz level. The prototypical vibrational molecular clock is shown to have a systematic fractional uncertainty at the 14th decimal place, matching the performance of the earliest optical atomic lattice clocks. As part of this effort, deeply bound strontium dimers are coherently created, and ultracold collisions of these Van der Waals molecules are studied for the first time, revealing inelastic losses at the universal rate. The thesis reports one of the most accurate measurements of a molecule’s vibrational transition frequency to date. The molecular clock lays the groundwork for explorations into terahertz metrology, quantum chemistry, and fundamental interactions at atomic length scales.

Keywords: ultracold molecules, strontium dimer, photodissociation, molecular clock, high-precision spectroscopy.

This thesis unites the fields of optical atomic clocks and ultracold molecular science, laying the foundation for optical molecular measurements of unprecedented precision. Building upon optical manipulation techniques developed by the atomic clock community, this work delves into attaining surgical control of molecular quantum states. The thesis develops two experimental observables that one can measure with optical-lattice-trapped ultracold molecules: extremely narrow optical spectra, and angular distributions of photofragments that are ejected when the diatomic molecules are dissociated by laser light pulses. The former allows molecular spectroscopy approaching the level of atomic clocks, leading into molecular metrology and tests of fundamental physics. The latter opens the field of ultracold chemistry through observation of quantum effects such as matter-wave interference of photofragments and tunneling through reaction barriers. The thesis also describes a discovery of a new method of thermometry that can be used near absolute zero temperatures for particles lacking cycling transitions, solving a long-standing experimental problem in atomic and molecular physics.

Advances in Atomic, Molecular, and Optical Physics publishes reviews of recent developments in a field which is in a state of rapid growth, as new experimental and theoretical techniques are used on many old and new problems. Topics covered include related applied areas, such as atmospheric science, astrophysics, surface physics and laser physics. Articles are written by distinguished experts, and contain both relevant review material and detailed descriptions of important recent developments. International experts Comprehensive articles New developments

The aim of this book is to present review articles describing the latest theoretical and experimental developments in the field of cold atoms and molecules. Our hope is that this series will promote research by both highlighting recent breakthroughs and by outlining some of the most promising research directions in the field.

The aim of this book is to present review articles describing the latest theoretical and experimental developments in the field of cold atoms and molecules. Our hope is that this series will promote research by both highlighting recent breakthroughs and by outlining some of the most promising research directions in the field.

The aim of this book is to present review articles describing the latest theoretical and experimental developments in the field of cold atoms and molecules. Our hope is that this series will promote research by both highlighting recent breakthroughs and by outlining some of the most promising research directions in the field.