Superfluid-Insulator Transitions in Attractive Bose-Hubbard Model with Three-Body Constraint

TL;DR

This paper investigates phase transitions in an attractive Bose-Hubbard model with a three-body constraint, revealing how Feshbach resonance coupling can change the nature of the transition from continuous to first-order, and predicting phase boundaries for experimental realization.

Contribution

It introduces an effective potential approach to analyze superfluid-insulator transitions, highlighting the role of Feshbach resonance coupling in the transition order and providing accurate phase boundary predictions.

Findings

Continuous transitions can be preempted by first-order ones due to Feshbach resonance.

The approach accurately predicts phase boundaries in the strong coupling limit.

The dimer superfluid phase can emerge in the phase diagram.

Abstract

By means of the method of the effective potential, the phase transitions from the Mott insulating state to either the atomic or the dimer superfluid state in the three-body constrained attractive Bose lattice gas are analyzed. Due to the appearance of the Feshbach resonance coupling between the two kinds of order parameters in the derived effective potential function, it is found that the continuous Mott insulator-to-superfluid transitions can be preempted by first-order ones. Since the employed approach can provide accurate predictions of phase boundaries in the strong coupling limit, where the dimer superfluid phase can emerge, our work hence sheds light on the search of this novel phase in real ultracold Bose gases in optical lattices.