The behavior of ultra-cold atoms in two-dimensional optical lattices with asymmetric periodic pinning potentials

We examine the disorder effect of the pinning potential acting on ultracold atoms in the optical lattice based on the expanded Bose-Hubbard model for soft-core bosons. Using Quantum Monte Carlo simulation with local optimal Worm algorithm, we obtain three additional crystal-like phase types at commensurate densities, rho = 1/2, 1, and 3/2 besides two basic phases which are superfluid and Mott insulator phases as observed in the bare soft-core boson model. In the presence of disorder, the superfluid and the charge-density wave coexist in the sandwiched regions between the superfluid and the solid orders around the commensurate densities. This observation signifies our work because it has not been revealed previously in other models of the soft-core bosons.

Automated summary

In this study, we investigate the disorder effect on ultracold atoms in an optical lattice by using the expanded Bose-Hubbard model and Quantum Monte Carlo simulation. We discover three additional crystal-like phases at commensurate densities, rho = 1/2, 1, and 3/2, in addition to the superfluid and Mott insulator phases observed in the bare soft-core boson model. In the presence of disorder, the superfluid and charge-density wave coexist in the sandwiched regions between the superfluid and solid orders around the commensurate densities. This observation is significant as it has not been previously revealed in other models of soft-core bosons.