Density dependent tunneling in the extended Bose-Hubbard model

TL;DR

This paper explores how density-dependent tunneling affects the phase diagrams of the extended Bose-Hubbard model in two dimensions, revealing significant differences from the standard model and no evidence of pair-superfluidity.

Contribution

It introduces the impact of density-dependent tunneling on the phase diagram of the 2D extended Bose-Hubbard model using Quantum Monte Carlo simulations.

Findings

Significant modifications in superfluid, supersolid, and phase-separated regions.

No evidence of pair-superfluidity in 2D, contrasting with 1D results.

Density-dependent tunneling alters the interplay of interactions in the model.

Abstract

Recently, it has become apparent that, when the interactions between polar molecules in optical lattices becomes strong, the conventional description using the extended Hubbard model has to be modified by additional terms, in particular a density-dependent tunneling term. We investigate here the influence of this term on the ground-state phase diagrams of the two dimensional extended Bose-Hubbard model. Using Quantum Monte Carlo simulations, we investigate the changes of the superfluid, supersolid, and phase-separated parameter regions in the phase diagram of the system. By studying the interplay of the density-dependent hopping with the usual on-site interaction U and nearest-neighbor repulsion V, we show that the ground-state phase diagrams differ significantly from the ones that are expected from the standard extended Bose-Hubbard model. However we find no indication of pair-superfluid behavior in this two dimensional square lattice study in contrast to the one-dimensional case.