Collective effects in a weakly interacting dipolar gas in free space

Ultracold gases with strong dipolar interactions are known to exhibit rich phases of matter, many of which have been observed in experiments with magnetic atoms and dipolar molecules. Here, we explore how long-range tails can collectively enhance dipolar interactions and induce dynamical stabilization even in the less-studied weakly interacting regime. Specifically, we theoretically study the expansion of a Bose-Einstein condensate prepared in a cigar-shaped trap in the presence of a far-off-resonant laser drive that induces weak dipole-dipole interactions. We show that phase-matching between the laser drive and the emitted field can collectively enhance the dipolar interactions to such a degree that the associated long-range attraction can overcome the short-range repulsion due to s-wave interactions, making the condensate self-bound. This phenomenon mirrors recent findings in cavity-QED systems but occurs here in a free-space, widely accessible experimental setting. Our results bridge the gap between free-space disordered arrays and cavity-mediated interactions, providing valuable insights for current state-of-the-art experiments.