2014/04/30 by Ole Jürgensen, Dirk-Sören Lühmann
Chemistry · Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Semiconductor Quantum Structures and Devices #Spectroscopy and Laser Applications #cond-mat.quant-gas
paper · pdf · doi:10.1088/1367-2630/16/9/093023
published as New J. Phys. 16 093023 (2014) · 7 pages, 4 figures
arxiv created 2014/09/10 · openalex publication_date 2014/09/19 · arxiv updated 2014/10/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
We study bosonic atoms in optical honeycomb lattices with anisotropic tunneling and find dimerized Mott insulator (MI) phases with fractional filling. These incompressible insulating phases are characterized by an interaction-driven localization of particles in respect to the individual dimers and large local particle-number fluctuations within the dimers. We calculate the ground-state phase diagrams and the excitation spectra using an accurate cluster mean-field method. The cluster treatment enables us to probe the fundamental excitations of the dimerized MI where the excitation gap is dominated by the intra-dimer tunneling amplitude. This allows the distinction from normal Mott insulating phases gapped by the on-site interaction. In addition, we present analytical results for the phase diagram derived by a higher-order strong-coupling perturbative expansion approach. By computing finite lattices with large diameters the influence of a harmonic confinement is discussed in detail. It is shown that a large fraction of atoms forms the dimerized MI under experimental conditions. The necessary anisotropic tunneling can be realized either by periodic driving of the optical lattice or by engineering directly a dimerized lattice potential. The dimers can be mapped to their antisymmetric states creating a lattice with coupled p -orbitals.