Electronic Dephasing in the Quantum Hall Regime

TL;DR

This study uses four-wave mixing to explore how quantum coherence of electron-hole pairs is affected by magnetic fields in quantum Hall systems, revealing a transition from Markovian to non-Markovian dynamics and decay time jumps at specific filling factors.

Contribution

It provides the first experimental evidence of non-Markovian dephasing in quantum Hall regimes and introduces a model incorporating collective excitations to explain the observations.

Findings

Transition from Markovian to non-Markovian behavior with increasing magnetic field

Large jumps in FWM decay time at even Landau level filling factors

Qualitative agreement with a model including collective excitations

Abstract

By means of degenerate four-wave mixing (FWM), we investigate the quantum coherence of electron-hole pairs in the presence of a two-dimensional electron gas in modulation-doped GaAs-AlGaAs quantum wells in the quantum Hall effect regime. With increasing magnetic field, we observe a crossover from Markovian to non-Markovian behavior, as well as large jumps in the decay time of the FWM signal at even Landau level filling factors. The main observations can be qualitatively reproduced by a model which takes into account scattering by the collective excitations of the two-dimensional electron gas.