Chiral Mott insulators in frustrated Bose-Hubbard models on ladders and two-dimensional lattices: a combined perturbative and density matrix renormalization group study

TL;DR

This paper investigates chiral Mott insulators in frustrated Bose-Hubbard models on ladders and 2D lattices, combining perturbative analysis and DMRG to understand their excitations and phase transitions.

Contribution

It demonstrates the existence of a low-lying exciton state responsible for CMI formation and characterizes quantum phase transitions using DMRG on various ladder geometries.

Findings

Existence of a low-lying exciton state with correct quantum numbers.

Characterization of two quantum phase transitions in ladder systems.

Potential to extend the CMI regime with additional interactions or parameter tuning.

Abstract

We study the fully gapped chiral Mott insulator (CMI) of frustrated Bose-Hubbard models on ladders and two-dimensional lattices by perturbative strong-coupling analysis and density matrix renormalization group (DMRG). First we show the existence of a low-lying exciton state on all geometries carrying the correct quantum numbers responsible for the condensation of excitons and formation of the CMI in the intermediate interaction regime. Then we perform systematic DMRG simulations on several two-leg ladder systems with $\pi$-flux and carefully characterize the two quantum phase transitions. We discuss the possibility to extend the generally very small CMI window by including repulsive nearest-neighbour interactions or changing density and coupling ratios.