P. J. H. Denteneer

Mott Domains of Bosons Confined on Optical Lattices

In the absence of a confining potential, the boson-Hubbard model exhibits a superfluid to Mott insulator quantum phase transition at commensurate fillings and strong coupling. We use quantum Monte Carlo simulations to study the ground state of the one-dimensional bosonic Hubbard model in a trap. Some, but not all, aspects of the Mott insulating phase persist. Mott behavior occurs for a continuous range of incommensurate fillings, very different from the unconfined case, and the establishment of the Mott phase does not proceed via a traditional quantum phase transition. These results have important implications for interpreting experiments on ultracold atoms on optical lattices.

Ultracold atoms in optical lattices

Bosonic atoms trapped in an optical lattice at very low temperatures can be modeled by the Bose-Hubbard model. In this paper, we propose a slave-boson approach for dealing with the Bose-Hubbard model, which enables us to analytically describe the physics of this model at nonzero temperatures. With our approach the phase diagram for this model at nonzero temperatures can be quantified.

CONDUCTING PHASE IN THE TWO-DIMENSIONAL DISORDERED HUBBARD MODEL

We study the temperature-dependent conductivity

Dynamic response of trapped ultracold bosons on optical lattices

\ensuremath{\sigma}(T)

Optimal Superconducting Critical Temperature in the Two-Dimensional Attractive Hubbard Model

and spin susceptibility

Total-energy and entropy considerations as a probe of chemical order in amorphous silicon carbide

\ensuremath{\chi}(T)

Particle-Hole Symmetry and the Effect of Disorder on the Mott-Hubbard Insulator

of the two-dimensional disordered Hubbard model. Calculations of the current-current correlation function using a quantum Monte Carlo method show that repulsion between electrons can significantly enhance the conductivity, and at low temperatures change the sign of

Phase Coherence, Visibility, and the Superfluid-Mott-Insulator Transition on One-Dimensional Optical Lattices

d\ensuremath{\sigma}/\mathrm{dT}

LOW-TEMPERATURE BEHAVIOR OF THE LARGE-U HUBBARD MODEL FROM HIGH-TEMPERATURE EXPANSIONS

from positive (insulating behavior) to negative (conducting behavior). This result suggests the possibility of a metallic phase, and consequently a metal-insulator transition, in a two-dimensional microscopic model containing both interactions and disorder. The metallic phase is a non-Fermi liquid with local moments as deduced from

Feshbach-einstein condensates.

\ensuremath{\chi}(T)