Speaker
Description
Ultracold molecules are a promising platform for diverse scientific goals, ranging from quantum information and simulation to controlled chemistry and precision measurements of fundamental physics. The rich internal structure of molecules, including vibrations, rotations, and hyperfine interactions, provides many handles for exquisite control. However, the very same structural features that make molecules so desirable to study also complicate the task of controlling them.
25 years ago at Harvard we started work to trap molecules and study their interactions. This was long before the idea of molecules as qbits had come onto the scene. We began with the simple idea that a very cold cryogenic gas could provide the dissipation to load molecules into a magnetic trap. This led to a series of experiments that included the first magnetic trapping of a molecule and study of collisional properties, in particular spin relaxation. We discovered that magnetic trapping was delicate and that only a few species of molecules would be amenable to our initial approach. This led us to separate the cooling mechanism from the trapping mechanism and gave birth to the buffer-gas beam. Later, this beam turned out to be ideally suited to the laser cooling of molecules, as done in several labs now, including our lab with CaF and SrOH.
Laser cooling and magneto-optical trapping of diatomic molecules from a buffer-gas beam has been realized. In our lab temperatures as low as a few $\mu$K have been achieved in long-lived, optically trapped samples of CaF. Photon cycling of these types of molecules allows for high fidelity detection of ultracold molecules and for increases in phase space density allowing for, e.g., the study of ultracold molecular collisions. In this talk, I will outline the path from the early days at Harvard to now a very large field of research on cold, trapped molecules including a path to ultracold polyatomic molecules. I will also present our latest results, which includes the trapping and high-fidelity readout of single molecules in optical tweezers.
