Synthesizing $2h/e^2$ resistance plateau at the first Landau level confined in a quantum point contact

TL;DR

This paper demonstrates a robust intermediate resistance plateau at 2h/e^2 in a quantum point contact within a fractional quantum Hall state, revealing new edge equilibration processes crucial for quantum Hall physics.

Contribution

It uncovers a novel intermediate resistance quantization at 2h/e^2 in a QPC at fractional fillings, highlighting specific edge equilibration mechanisms.

Findings

Observation of 2h/e^2 resistance plateau at 2/3 filling

Identification of two edge equilibration processes

Similar quantization observed at 5/3 filling

Abstract

A comprehensive understanding of quantum Hall edge transmission, especially the hole-conjugate of a Laughlin state such as a $2/3$ state, is critical for advancing fundamental quantum Hall physics and enhancing the design of quantum Hall edge interferometry. In this study, we report a robust intermediate $2h/e^2$ resistance quantization in a quantum point contact (QPC) when the bulk is set at the fractional filling $2/3$ quantum Hall state. Our results suggest the occurrence of two equilibration processes. First, the co-propagating $1/3$ edges moving along a soft QPC arm confining potential fully equilibrate and act as a single $2/3$ edge mode. Second, the $2/3$ edge mode is further equilibrated with an integer $1$ edge mode formed in the QPC. The complete mixing between them results in a diagonal resistance value quantized at $2h/e^2$. Similar processes occur for a bulk filling $5/3$, leading to an intermediate $(2/3)h/e^2$ resistance quantization.