Tunable dipolar interactions and collisional shielding in a quantum gas of polar molecules

Abstract: Ultracold molecules have rich internal structure and tunable dipolar interactions, making them an exciting platform for studying quantum many-body physics. However, controlling molecular interactions, especially chemical reaction losses, has remained an experimental challenge. We demonstrate two approaches for tuning molecular interactions: strong 2D confinement and electric-field-induced shielding resonances. Both methods enable a high ratio of elastic to inelastic collisions, enabling direct evaporative cooling and the creation of long-lived and strongly dipolar molecular quantum gases. We also describe control of individual layers of molecules in a 1D optical lattice and initial studies of dipolar mean field shifts in a 2D molecular gas.