Terahertz Coherent Control of a Landau-Quantized Two-Dimensional Electron Gas

TL;DR

This paper demonstrates the coherent control of cyclotron resonance in a two-dimensional electron gas using terahertz pulses, revealing self-interaction effects and validating single-particle models within the decoherence time.

Contribution

It introduces a method to coherently manipulate CR in 2DEG with terahertz pulses and confirms the applicability of single-particle models in this regime.

Findings

Controlled CR oscillations via phase-dependent terahertz pulses

Observation of self-interaction effects leading to revival and collapse of coherence

Validation of Kohn's theorem in the coherent control regime

Abstract

We demonstrate coherent control of cyclotron resonance (CR) in a two-dimensional electron gas (2DEG). We use a sequence of terahertz pulses to control the amplitude of CR oscillations in an arbitrary fashion via phase-dependent coherent interactions. We observe a self-interaction effect, where the 2DEG interacts with the terahertz field emitted by itself within the decoherence time, resulting in a revival and collapse of quantum coherence. These observations are accurately describable using {\em single-particle} optical Bloch equations, showing no signatures of electron-electron interactions, which verifies the validity of Kohn's theorem for CR in the coherent regime.