# Photocurrent and photoconductance of an helical edge state

## TL;DR

This paper investigates how circularly polarized light influences photocurrent and photoconductance in the helical edge states of a Quantum Spin Hall insulator, considering lead effects and electronic doping.

## Contribution

It provides a detailed analysis of photocurrent generation and photoconductance modulation in helical edge states under electromagnetic irradiation, including lead effects and doping.

## Key findings

- Photocurrent depends on electromagnetic wave characteristics and doping levels.
- Lead connections significantly influence the photocurrent response.
- Photoconductance varies with applied voltage bias and irradiation conditions.

## Abstract

We consider the helical edge state of a Quantum Spin Hall insulator, connected between two leads, and irradiated by a monochromatic and circularly polarized electromagnetic wave. The photocurrent generated within the helical edge state is studied as function of the characteristics of the electromagnetic radiation and electronic doping of the edge state. We focus on the effect of the leads on the photocurrent. We also investigate the photoconductance of the helical edge state in presence of a voltage bias between the leads.