Ultrafast dynamics of coherences in the quantum Hall system

TL;DR

This study employs three-pulse four-wave-mixing spectroscopy to investigate ultrafast quantum coherence dynamics in quantum Hall systems, revealing many-particle interactions and coherence dephasing effects.

Contribution

It introduces a microscopic theory explaining observed coherences and provides quantitative analysis of their dephasing in quantum Hall systems.

Findings

Detection of large off-resonant signals with oscillations

Identification of many-particle coherences due to carrier interactions

Quantitative insights into coherence dephasing and interference

Abstract

Using three-pulse four-wave-mixing optical spectroscopy, we study the ultrafast dynamics of the quantum Hall system. We observe striking differences as compared to an undoped system, where the 2D electron gas is absent. In particular, we observe a large off-resonant signal with strong oscillations. Using a microscopic theory, we show that these are due to many-particle coherences created by interactions between photoexcited carriers and collective excitations of the 2D electron gas. We extract quantitative information about the dephasing and interference of these coherences.