PRA: Crystallization of dipolar bosons and its detection in single-shot images

The long-ranged and anisotropic dipole-dipole interactions entail rich quantum many-body physics, distinct from the effects in ultracold atoms with contact interactions. The focus of this paper is the remarkable crystallization process that takes place if the dipole-dipole interactions are strong enough to dominate the physics of the system. In the crystal state, the dipolar atoms localize due to their long-range interactions and form a crystal structure irrespective of the confining potential. We define an order parameter, Δ, that is a function of the eigenvalues of the reduced one-body density matrix [panel (a)]. We show that this order parameter characterizes all the emergent phases of the system, the superfluid, the Mott insulator, attempted fermionization, and crystallization. Importantly, the order parameter [panel (a)] can be inferred from the variance of single-shot images, i.e., by quantifying the fluctuations in the ``photos'' taken of the wavefunction that are the typical result of cold-atom experiments. Read more on arXiv:1708.07409 and PRA, 98, 053624 (2018).