Speaker: Jun-Ru Li, JILA, NIST and University of Colorado, Boulder
Abstract: Ultracold polar molecules possess rich internal structure and support dipolar interactions, bringing new opportunities for studying quantum phenomena. Complete control of molecular quantum systems has long been hindered by chemical reactions. In this talk, I will describe results emerging from our recent implementation of exquisite control of the molecular interaction processes. By using an electric field-induced shielding resonance, we suppress the two-body reactive loss in a three-dimensional gas by a factor of 30 while preserving the strong dipolar elastic collisions. In a quasi-two-dimensional geometry where the molecular motion is constrained, we demonstrate that such loss is suppressed by aligning dipoles perpendicular to the plane of motion and exploiting the repulsive channel of the dipolar interactions. Implementing these techniques brings molecular gases into a new regime where elastic collisions dominate, leading to rapid dipolar thermalization and direct evaporative cooling to quantum degeneracy. A feature of the dipolar interaction is its long interaction range. Recently, we have created a stack of two-dimensional layers of molecules where we can control the states of the molecules in each individual layer. We directly observed and controlled interactions between molecules in and between these isolated layers. These research results have brought molecular control to a new regime, highlighting the promise of ultracold molecular gases as a new platform for quantum science.