Fractional quantum Hall states with variational Projected Entangled-Pair States: a study of the bosonic Harper-Hofstadter model

TL;DR

This paper demonstrates that variational infinite projected-entangled pair states (iPEPS) can effectively identify fractional quantum Hall states in the bosonic Harper-Hofstadter model, revealing topological order and edge modes.

Contribution

It shows, contrary to previous no-go theorems, that variational iPEPS can be used to study topological fractional quantum Hall states on lattice models.

Findings

Identified fractional Hall states with iPEPS in the bosonic Harper-Hofstadter model.

Characterized states by exponential decay of bulk correlations and chiral edge modes.

Confirmed the presence of a bulk gap and topological order.

Abstract

An important class of model Hamiltonians for investigation of topological phases of matter consists of mobile, interacting particles on a lattice subject to a semi-classical gauge field, as exemplified by the bosonic Harper-Hofstadter model. A unique method for investigations of two-dimensional quantum systems are the infinite projected-entangled pair states (iPEPS), as they avoid spurious finite size effects that can alter the phase structure. However, due to no-go theorems in related cases this was often conjectured to be impossible in the past. In this letter, we show that upon variational optimization the infinite projected-entangled pair states can be used to this end, by identifying fractional Hall states in the bosonic Harper-Hofstadter model. The obtained states are characterized by showing exponential decay of bulk correlations, as dictated by a bulk gap, as well as chiral edge modes via the entanglement spectrum.