Formation of liquids in low-dimensional dipolar systems
Grigori Astrakharchik (Barcelona Tech – UPC)
Hybrid: onsite seminar + zoom.
Meeting ID: 958 7591 9260
We show that ultradilute quantum liquids can be formed with ultracold bosonic dipolar atoms in a bilayer geometry. Contrary to previous realizations of ultradilute liquids, there is no need for stabilizing the system with an additional repulsive short-range potential. The advantage of the proposed system is that dipolar interactions on their own are sufficient for creation of a self-bound state and no additional short-range potential is needed for the stabilization. We perform quantum Monte Carlo simulations and find a rich ground-state phase diagram that contains quantum phase transitions between liquid, solid, atomic gas, and molecular gas phases.
Optical lattices with dipolar bosons provide a unique platform for fundamental studies of the extended Bose-Hubbard model. The interplay between anisotropic long-range interaction, strong on-site repulsion and periodic confinement give rise to unexpected phases of matter that have not been explored so far in experiments. We propose a mechanism that stabilizes quantum liquids in strongly interacting dipolar gases in a one-dimensional optical lattice. The mechanism is based on the enhanced role of the superexchange processes close to a self-bound Mott insulator state. To support this finding, we contrast our perturbative calculations with full density-matrix renormalization group simulations and characterize the properties of different phases of the system.
 G. Guijarro, G. E. Astrakharchik, J. Boronat, Ultradilute quantum liquid of dipolar atoms in a bilayer, Phys. Rev. Lett. 128, 063401 (2022)
 Ivan Morera, Rafał Ołdziejewski, Grigori E. Astrakharchik, Bruno Juliá-Díaz, Superexchange liquefaction of strongly correlated lattice dipolar bosons, arXiv:2204.03906