Detecting edge degeneracy in interacting topological insulators through entanglement entropy

TL;DR

This paper introduces a novel entanglement entropy-based method to detect edge degeneracy in interacting topological insulators, using quantum Monte Carlo simulations to analyze interaction effects on edge states.

Contribution

It proposes a new approach to identify edge degeneracies in interacting topological insulators via entanglement entropy, applicable to models in one and two dimensions.

Findings

Edge degeneracies are reduced but remain nontrivial under interactions.

The method effectively detects edge states in interacting topological phases.

Quantum Monte Carlo confirms the robustness of the approach.

Abstract

The existence of degenerate or gapless edge states is a characteristic feature of topological insulators, but is difficult to detect in the presence of interactons. We propose a new method to obtain the degeneracy of the edge states from the perspective of entanglement entropy, which is very useful to identify interacting topological states. Employing the determinant quantum Monte Carlo technique, we investigate the interaction effect on two representative models of fermionic topological insulators in one and two dimensions, respectively. In the two topologically nontrivial phases, the edge degeneracies are reduced by interactions but remain to be nontrivial.