Ultrafast Nonequilibrium Dynamics in Two-dimensional Quantum Spin-Hall Materials

TL;DR

This paper develops a theoretical framework for ultrafast nonequilibrium photonics in 2D quantum spin-Hall insulators, revealing topology-dependent nonlinear optoelectronic phenomena and guiding experimental identification of topological states.

Contribution

It introduces a novel theoretical approach to study ultrafast light-matter interactions in topological 2D materials, linking high harmonic spectra to topological invariants.

Findings

Topological Dirac fermions exhibit distinct high harmonic signatures.

Strong femtosecond light pulses induce non-adiabatic quantum dynamics.

Spectroscopy can identify topological electronic states.

Abstract

We develop the theoretical framework of nonequilibrium ultrafast photonics in monolayer quantum spin-Hall insulators supporting a multitude of topological states. In these materials, ubiquitous strong light-matter interactions in the femtosecond scale lead to non-adiabatic quantum dynamics, resulting in topology-dependent nonlinear optoelectronic transport phenomena. We investigate the mechanism driving topological Dirac fermions interacting with strong ultrashort light pulses and uncover various experimentally accessible physical quantities that encode fingerprints of the quantum material's topological electronic state from the high harmonic generated spectrum. Our work sets the theoretical cornerstones to realize the full potential of time-resolved harmonic spectroscopy for identifying topological invariants in two-dimensional quantum spin-Hall solid state systems.