Universal Bound States with Bose-Fermi Duality in Microwave-Shielded Ultracold Molecules
Phys. Rev. Lett. 136, 043402 – Published 26 January, 2026
DOI: https://doi.org/10.1103/hcwf-tk6c
Abstract
We report universal bound states of microwave-shielded ultracold molecules that solely depend on the strengths of long-range dipolar interaction and microwave coupling. Under a highly elliptic microwave field, few-molecule scatterings in three dimensions are shown to be governed by effective one-dimensional (1D) models, which well reproduce the tetratomic bound state and the Born-Oppenheimer potential in three-molecule sector. For hexatomic systems comprising three identical molecules, we find a much deeper bound state than the tetratomic one, with binding energy exceeding twice the latter. Strikingly, these bound states display Bose-Fermi duality as facilitated by the effective 1D scattering with a large repulsive core from angular fluctuations. For large molecule ensembles, our results suggest the formation of elongated self-bound droplets with crystalline patterns in both bosonic and fermionic molecules.