Quantum dot coupled to topological insulators: The role of edge states

TL;DR

This paper studies how edge states in topological insulator leads influence a coupled quantum dot, revealing characteristic features in spectral and transport properties that can identify the topological phase.

Contribution

It demonstrates that edge-state features in a quantum dot system are robust or enhanced by interactions and can serve as indicators of the topological phase of the leads.

Findings

Edge states cause distinctive features in the dot spectral function.

These features are robust or enhanced by local two-particle interactions.

Characteristic features can identify topologically non-trivial phases.

Abstract

We investigate a system consisting of one or two topological-insulator leads which are tunnel coupled to a single dot level. The leads are described by the one-dimensional Su-Schrieffer-Heeger model. We show that (topological) edge states cause characteristic features in the dot spectral function, the dot occupation, and the finite-bias current across the dot. As the kinetic energy is quenched in the dot region, local two-particle interactions are of particular relevance there. This motivates us to test whether the aforementioned edge-state features are robust against such interactions; we report here that they are either robust or even enhanced. We conclude that the characteristic features can be used to determine if the leads are in their topologically non-trivial or trivial phase.