Extreme loss suppression in an ultracold molecular gas with widely tunable dipolar interactions.

Ultracold dipolar molecules hold great promise for the creation of exotic quantum states of matter, but the realization of long-lived molecular bulk samples with strong dipole-dipole interactions has remained challenging. In this work, we realized a collisionally stable gas of ultracold ground state molecules with a lifetime of several seconds. Utilizing double-microwave dressing, we achieved an extreme suppression of inelastic two- and three-body losses by factors of more than 10,000 and 1000, respectively. We found that losses remained suppressed across a wide range of dipole-dipole interactions, allowing the continuous tuning of the dipolar length from -21,000 to 12,000 a0, where a0 is the Bohr radius. Combined with the recent realization of Bose-Einstein condensation of dipolar molecules, our findings open the door to the exploration of strongly dipolar quantum liquids.