# Topological edge state engineering with high-frequency electromagnetic radiation

## TL;DR

This paper demonstrates how high-frequency electromagnetic radiation can be used to induce and control topological phase transitions and edge state properties in two-dimensional topological insulators, specifically HgTe quantum wells.

## Contribution

It introduces a method to manipulate topological phases and edge state characteristics using off-resonant laser fields, even below the critical well thickness.

## Key findings

- Laser coupling can induce topological phase transitions.
- Edge state group velocity can be tuned by laser intensity.
- Control over topological properties enables new experimental and technological applications.

## Abstract

We outline here how strong light-matter interaction can be used to induce quantum phase transition between normal and topological phases in two-dimensional topological insulators. We consider the case of a HgTe quantum well, in which band inversion occurs above a critical value of the well thickness, and demonstrate that coupling between electron states and the $E$ field from an off-resonant linearly polarized laser provides a powerful tool to control topological transitions, even for a thickness of the quantum well that is below the critical value. We also show that topological phase properties of the edge states, including their group velocity, can be tuned in a controllable way by changing the intensity of the laser field. These findings open up the possibility for new experimental means with which to investigate topological insulators and shed new light on topological-insulator-based technologies that are under active discussion.