Transverse Field Dependence of the Ground State in the Z2 Bose-Hubbard Model

TL;DR

This paper investigates how spin fluctuations influence the ground state of the Z2 Bose-Hubbard model, revealing a phase transition between nonuniform states and analyzing the effects of a strong transverse magnetic field.

Contribution

It provides the first detailed analysis of the ground state phase transition in the Z2 Bose-Hubbard model using density-matrix renormalization group methods.

Findings

Identified a phase transition between two nonuniform states.

Analyzed the ground state behavior under strong transverse magnetic field.

Calculated spin structure factor and compressibility to characterize phases.

Abstract

The study of interaction between the particle and lattice degrees of freedom is one of the central interests in the quantum many-body systems. The Z2 Bose-Hubbard model has been proposed to describe ultracold bosons in a dynamical optical lattice. This model introduces the lattice degrees of freedom by placing half-spins on the bonds between neighboring lattice sites. In this study, we investigate the effect of spin fluctuations on the ground state by using the density-matrix renormalization group method. By calculating the spin structure factor and the compressibility, we show that there is a phase transition between two spatially nonuniform states. We also discuss the ground state in the strong transverse magnetic field.