Shot Noise and Fractional Charge at the 2/3 Composite Fractional Edge Channel

TL;DR

This study investigates shot noise in the 2/3 fractional quantum Hall state, revealing temperature-dependent fractional charges and unexpected noise behavior, challenging existing models of edge channel structure.

Contribution

It provides detailed shot noise measurements of the 2/3 state, uncovering fractional charge variations and unusual noise patterns that suggest a new understanding of composite edge channels.

Findings

Fractional charge of (2/3)e at low temperature

Charge decreases to e/3 at higher temperature

Strong shot noise observed on the 1/3 plateau

Abstract

The exact structure of edge modes in `hole conjugate' fractional quantum Hall states remains an unsolved issue despite significant experimental and theoretical efforts devoted to their understanding. Recently, there has been a surge of interest in such studies led by the search for neutral modes, which in some cases may lead to exotic statistical properties of the excitations. In this letter we report on detailed measurements of shot noise, produced by partitioning of the more familiar 2/3 state. We find a fractional charge of (2/3)e at the lowest temperature, decreasing to e/3 at an elevated temperature. Surprisingly, strong shot noise had been measured on a clear 1/3 plateau upon partitioning the 2/3 state. This behavior suggests an uncommon picture of the composite edge channels quite different from the accepted one.