Exploring Strongly Interacting Dipolar Quantum Gases of Ultracold Molecules

Long-range dipolar interactions in ground-state molecules provide a powerful platform to explore new regimes of interacting quantum matter. The recent realization of Bose-Einstein condensates of NaCs molecules in our lab (Bigagli et al, Nature 631, 289-293) opens up a new platform. Thanks to the extreme suppression of inelastic losses in our molecular samples even at sizable dipolar interactions (Yuan et al., arXiv:2505.08773), we can study bulk gases where dipolar interactions dominate the system dynamics. Using microwave dressing, both the strength and anisotropy of these interactions can be precisely tuned while maintaining long molecular lifetimes. Dipolar, antidipolar, and more complex spatial patterns of long-range interactions give rise to rich collective behavior, including droplet arrays and other interaction-driven structures (Zhang et al., arXiv:2507.15208). Looking ahead, loading these Bose-Einstein condensates of dipolar molecules into optical lattices will enable investigations of non-standard Hubbard and spin models.