Moir\'e-Bose-Hubbard model for interlayer excitons in twisted transition metal dichalcogenide heterostructures

TL;DR

This paper models interlayer excitons in twisted TMD heterostructures using a moiré-Bose-Hubbard Hamiltonian, predicting Mott-insulating states and suggesting their potential as quantum simulators for bosonic systems.

Contribution

It introduces a moiré-Bose-Hubbard model for interlayer excitons, deriving parameters from Wannier functions and dielectric screening, to explore correlated exciton phases.

Findings

Prediction of Mott-insulating exciton states at low concentrations

Establishment of twisted TMD heterostructures as quantum simulators

Quantitative modeling of exciton interactions and hopping

Abstract

In bilayers of semiconducting transition metal dichalcogenides, the twist angle between layers can be used to introduce a highly regular periodic potential modulation on a length scale that is large compared to the unit cell. In such structures, correlated states can emerge, in which excitons in the heterostructure are strongly localized to the potential minima due to exciton-exciton interactions. We explore the transition between Mott and extended exciton phases in terms of a moir\'e-Bose-Hubbard Hamiltonian. Hopping and on-site interaction parameters are obtained from a Wannier representation of the interlayer-exciton wave functions, and a non-local Rytova-Keldysh model is used to attribute for the dielectric screening of excitons in the two-dimensional material. For sufficiently small exciton concentrations and substrate screening our model predicts the emergence of Mott-insulating states, establishing twisted TMD heterostructures as possible quantum simulators for bosonic many-body systems.