Bosonic quantum Hall states in single-layer two-dimensional optical lattices

TL;DR

This paper investigates bosonic quantum Hall states in 2D optical lattices using the Bose-Hubbard model with artificial gauge fields, revealing conditions for their stability and potential experimental signatures.

Contribution

It demonstrates the existence and stability conditions of bosonic quantum Hall states in optical lattices using advanced theoretical methods, including cluster Gutzwiller mean field and exact diagonalization.

Findings

QH states occur at specific flux and filling factors

QH states are sensitive to lattice geometry and potential type

QH states persist under certain shallow envelope potentials

Abstract

Quantum Hall (QH) states of 2D single layer optical lattices are examined using Bose-Hubbard model (BHM) in presence of artificial gauge field. We study the QH states of both the homogeneous and inhomogeneous systems. For the homogeneous case we use cluster Gutzwiller mean field (CGMF) theory with cluster sizes ranging from $2\times 2$ to $5\times 5$. We, then, consider the inhomogeneous case, which is relevant to experimental realization. In this case, we use CGMF and exact diagonalization (ED). The ED studies are using lattice sizes ranging from $3\times 3$ to $4\times 12$. Our results show that the geometry of the QH states are sensitive to the magnetic flux $\alpha$ and cluster sizes. For homogeneous system, among various combinations of $1/5\leqslant \alpha\leqslant 1/2$ and filling factor $\nu$, only the QH state of $\alpha=1/4$ with $\nu=1/2$, $1$, $3/2$ and $2$ occur as ground states. For other combinations, the competing superfluid (SF) state is the ground state and QH state is metastable. For BHM with envelope potential all the QH states observed in homogeneous system exist for box potentials, but none for the harmonic potential. The QH states also persist for very shallow Gaussian envelope potential. As a possible experimental signature we study the two point correlations of the QH and SF states.