Half-integer Mott-insulator phases in the imbalanced honeycomb lattice

TL;DR

This paper predicts novel half-integer Mott-insulator phases in an imbalanced honeycomb lattice of ultracold bosons, highlighting the role of quantum correlations and lattice topology, with potential experimental detection.

Contribution

It introduces the existence of half-integer Mott-insulator phases using an improved mean-field approach considering correlations, a novel finding in lattice quantum gases.

Findings

Prediction of half-integer Mott-insulator phases

Correlation effects are crucial for phase stability

Clear experimental signatures in momentum space

Abstract

Using mean-field theory, we investigate the ground state properties of ultracold bosons loaded in a honeycomb lattice with on-site repulsive interactions and imbalanced nearest-neighbor hopping amplitudes. Taking into account correlations between strongly coupled neighboring sites through an improved Gutzwiller ansatz, we predict the existence of half-integer Mott-insulator phases, i.e. states with half-integer filling and vanishing compressibility. These insulating phases result from the interplay between quantum correlations and the topology of the honeycomb lattice, and could be easily addressed experimentally as they have clear signatures in momentum space.