Bose-Hubbard model in the presence of artificial magnetic fields: Ground state and thermal phase diagrams

TL;DR

This paper investigates how artificial magnetic fields influence the ground state and phase diagrams of the two-dimensional Bose-Hubbard model, revealing localization, real space modulations, vortex formations, and phase robustness at finite temperatures.

Contribution

It demonstrates the effects of artificial gauge fields on bosonic phases, including localization, symmetry restoration, and vortex configurations, expanding understanding of magnetic field impacts on lattice boson systems.

Findings

Artificial magnetic fields localize bosons and expand insulator and supersolid regions.

Real space modulations of superfluid and supersolid phases are observed.

Vortex configurations depend on magnetic field and lattice commensuration.

Abstract

We consider effects of artificial magnetic fields on the ground state of the two-dimensional Bose-Hubbard model. Using an asymmetric Bose-Hubbard model, we demonstrate that the frustrating hopping energy localizes bosons and enlarges insulators and supersolid borders. We show these increments in the presence of artificial gauge fields up to a symmetric point of the field. Moreover, our calculations exhibit the real space modulations of the superfluid and supersolid phases. The bosonic current exhibits vortices in these phases, which their configurations depend on the commensuration between the magnetic field and the lattice. Although the magnetic field breaks the translational symmetry of the square lattice explicitly, this symmetry is restored in the Mott insulator phase. The filling factor exhibits a checkerboard pattern in the density-wave and supersolid phases, regardless of the magnetic field strength. We explore thermal fluctuations and demonstrate the robustness of insulators and SS phases up to temperatures comparable to the interaction energy, which support the feasibility of observing such phases in experiments.