Photo-assisted shot noise in the fractional quantum Hall regime

TL;DR

This paper investigates how an ac perturbation affects shot noise in fractional quantum Hall systems, revealing singularities linked to quasiparticle charges and proposing photo-assisted transport as a tool to measure these charges.

Contribution

It demonstrates that photo-assisted shot noise in fractional quantum Hall regimes exhibits unique singularities related to quasiparticle charges, providing a new method to probe fractional charge effects.

Findings

Singularities in shot noise are evenly spaced and related to quasiparticle charge.

Spacing depends on the ratio of bias voltage to drive frequency.

Photo-assisted transport can serve as a probe for fractional charges.

Abstract

The effect of an ac perturbation on the shot noise of a fractional quantum Hall fluid is studied at finite temperature. For a normal metal, it is known that the zero-frequency noise derivative exhibits steps as a function of bias voltage. In contrast, at Laughlin fractions, the backscattering noise exhibits evenly spaced singularities, which are reminiscent of tunneling density-of-states singularities for quasiparticles. The spacing is determined by the quasiparticle charge $\nu e$ and the ratio of the dc bias with respect to the drive frequency. Photo-assisted transport can thus be considered as a probe for effective charges of the quantum Hall effect.