Time-resolved investigation of plasmon mode along interface channels in integer and fractional quantum Hall regimes

TL;DR

This study uses time-resolved measurements to explore plasmon modes along quantum Hall interface channels, revealing dissipation effects from charge puddles and demonstrating potential for high-quality fractional charge transport.

Contribution

It provides the first detailed time-resolved analysis of interface plasmon modes in both integer and fractional quantum Hall regimes, highlighting dissipation mechanisms and transport properties.

Findings

Charge puddles cause waveform delay and broadening.

Dissipation significantly affects plasmon transport in gated regions.

Fractional interface channels can achieve fast velocities with reduced dissipation.

Abstract

Quantum Hall (QH) edge channels appear not only along the edge of the electron gas but also along an interface between two QH regions with different filling factors. However, the fundamental transport characteristics of such interface channels are not well understood, particularly in the high-frequency regime. In this study, we investigate the interface plasmon mode along the edge of a metal gate electrode with ungated and gated QH regions in both integer and fractional QH regimes using a time-resolved measurement scheme. The observed plasmon waveform was delayed and broadened due to the influence of the charge puddles formed around the channel. The charge velocity and diffusion constant of the plasmon mode were evaluated by analyzing the waveform using a distributed circuit model. We found that the conductive puddles in the gated region induce significant dissipation in plasmon transport. For instance, a fractional interface channel with a reasonably fast velocity was obtained by preparing a fractional state in the ungated region and an integer state in the gated region, whereas a channel in the swapped configuration was quite dissipative. This reveals a high-quality interface channel that provides a clean path to transport fractional charges for studying various fractional QH phenomena.