Dimerized Mott insulators in hexagonal optical lattices

Abstract

We study bosonic atoms in optical honeycomb lattices with anisotropic tunneling and find dimerized Mott insulator 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 Mott insulator 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 Mott insulator 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 to their antisymmetric states creating a lattice with coupled p-orbitals.

7 pages, 4 figures

References in corpus (31)

• Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
• Cold bosonic atoms in optical lattices
• Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice
• Time-resolved Observation and Control of Superexchange Interactions with Ultracold Atoms in Optical Lattices
• Dynamical control of matter-wave tunneling in periodic potentials
• Tunable gauge potential for neutral and spinless particles in driven lattices
• Superfluid-insulator transition in a periodically driven optical lattice
• Ultracold Atoms in a Tunable Optical Kagome Lattice
• Artificial graphene as a tunable Dirac material
• Controlled exchange interaction between pairs of neutral atoms in an optical lattice
• Short-range quantum magnetism of ultracold fermions in an optical lattice
• A lattice of double wells for manipulating pairs of cold atoms
• Non-Abelian gauge fields and topological insulators in shaken optical lattices
• Strong-coupling expansions for the pure and disordered bose Hubbard model
• Multi-Component Quantum Gases in Spin-Dependent Hexagonal Lattices
• Simulation and detection of Dirac fermions with cold atoms in an optical lattice
• The $p_{x,y}$-orbital counterpart of graphene: cold atoms in the honeycomb optical lattice
• Atomic quantum gases in Kagomé lattices
• Phase diagram of the bose Hubbard model
• Phase Diagram of Bosonic Atoms in Two-Color Superlattices
• Quantum phase transition to unconventional multi-orbital superfluidity in optical lattices
• Artificial graphene with tunable interactions
• Defect-Suppressed Atomic Crystals in an Optical Lattice
• Exact Study of the 1D Boson Hubbard Model with a Superlattice Potential
• Relativistic quantum effects of Dirac particles simulated by ultracold atoms
• Quantum phases of bosons in double-well optical lattices
• Bose-Einstein Condensate in a Honeycomb Optical Lattice: Fingerprint of Superfluidity at the Dirac Point
• Multi-site mean-field theory for cold bosonic atoms in optical lattices
• Laser probing of single-particle energy gap of a Bose gas in an optical lattice in the Mott insulator phase
• Quantum phases in tunable state-dependent hexagonal optical lattices
• Application of a multi-site mean-field theory to the disordered Bose-Hubbard model

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• Spatial Coherence of a Strongly Interacting Bose Gas in the Trimerized Kagome Lattice
• Generalized effective-potential Landau theory for a tunable state-dependent hexagonal optical lattice