Erlangen 2018 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 28: Cold atoms V - optical lattices (joint session A/Q)

Q 28.2: Vortrag

Dienstag, 6. März 2018, 14:15–14:30, K 0.011

Multimode Bose-Hubbard model for quantum dipolar gases in confined geometries — Florian Cartarius¹, •Rebecca Kraus¹, Ferdinand Tschirsich², Simone Montangero^1,2, Anna Minguzzi³, and Giovanna Morigi¹ — ¹Theoretische Physik, Universität des Saarlandes, D-66123 Saarbrücken, Germany — ²Institute for Complex Quantum systems, Universität Ulm, D-89069 Ulm, Germany — ³Université Grenoble-Alpes, CNRS, Laboratoire de Physique et Modélisation des Milieux Condensés, F-38000 Grenoble, France

We theoretically consider ultracold polar bosonic molecules in a wave guide. The particles experience a periodic potential due to an optical lattice oriented along the wave guide and are polarized by an electric field orthogonal to the guide axis. The array is mechanically unstable by opening the transverse confinement in the direction orthogonal to the polarizing electric field and can undergo a transition to a double-chain (zigzag) structure. For this geometry we derive a multimode generalized Bose-Hubbard model for determining the quantum phases of the gas at the mechanical instability, taking into account the quantum fluctuations in all directions of space. We determine the phase diagrams using exact diagonalization and an imaginary time-evolving block decimation program, where we also investigate the emergence of a Haldane insulating phase. We find that, even for tight transverse confinement, the aspect ratio between the two transverse trap frequencies controls not only the classical but also the quantum properties of the ground state in a nontrivial way.