Morphology of dipolar Bose droplets

The ground state of a free standing, self-bound droplet comprising four hundred dipolar Bose particles with aligned dipole moments, with an additional purely repulsive two-body interaction, is investigated by Quantum Monte Carlo simulations. The focus here is on the evolution of the cluster as the effective range of the repulsive interaction is varied. We identify a "classical" regime, in which binding arises exclusively from the dipolar potential energy and the cluster is a quasi-one-dimensional filament, and a "quantum" regime of prolate droplets, held together to a significant degree by quantum-mechanical exchanges. The transition between the two regimes occurs abruptly.