2025/07/21 by Siwei Zhang, Zhang, Siwei, Weijun Yuan +11 · 7 citations
Physics and Astronomy · #Atomic Physics (physics.atom-ph) #Atomic and Molecular Clusters (physics.atm-clus) #Cold Atom Physics and Bose-Einstein Condensates #FOS: Physical sciences #Quantum Gases (cond-mat.quant-gas) #Quantum Physics (quant-ph) #Quantum, superfluid, helium dynamics #Strong Light-Matter Interactions
paper · pdf · doi:10.48550/arxiv.2507.15208
openalex publication_date 2025/07/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Ultracold gases of dipolar molecules have long been envisioned as a platform for the realization of novel quantum phases. Recent advances in collisional shielding, protecting molecules from inelastic losses, have enabled the creation of degenerate Fermi gases and, more recently, Bose-Einstein condensation of dipolar molecules. However, the observation of quantum phases in ultracold molecular gases that are driven by dipole-dipole interactions has so far remained elusive. In this work, we report the formation of self-bound droplets and droplet arrays in an ultracold gas of strongly dipolar sodium-cesium molecules. Starting from a molecular Bose-Einstein condensate (BEC), microwave dressing fields are used to induce dipole-dipole interactions with controllable strength and anisotropy. By varying the speed at which interactions are induced, covering a dynamic range of four orders of magnitude, we prepare droplets under equilibrium and non-equilibrium conditions, observing a transition from robust one-dimensional (1D) arrays to fluctuating two-dimensional (2D) structures. The droplets exhibit densities up to 100 times higher than the initial BEC, reaching the strongly interacting regime, and suggesting the possibility of a quantum-liquid or crystalline state. This work establishes ultracold molecules as a system for the exploration of strongly dipolar quantum matter and opens the door to the realization of self-organized crystal phases and dipolar spin liquids in optical lattices.