Colored delta-T noise in Fractional Quantum Hall liquids

TL;DR

This paper investigates finite frequency delta-T noise in quantum point contacts, comparing Fermi liquids and fractional quantum Hall systems, revealing how strong correlations influence emission noise behavior.

Contribution

It provides a detailed analysis of delta-T noise in fractional quantum Hall liquids using chiral Luttinger liquid theory, highlighting differences from Fermi liquids.

Findings

Distinct noise behaviors for fractional quantum Hall and Fermi liquids.

Quadratic temperature difference expansion of emission noise.

Closer to Fermi liquid behavior in strong backscattering regime.

Abstract

Photons are emitted or absorbed by a nano-circuit under both equilibrium and non-equilibrium situations. Here, we focus on the non-equilibrium situation arising due to a temperature difference between the leads of a quantum point contact, and study the finite frequency (colored) noise. We explore this delta-$T$ noise in the finite frequency regime for two systems: conventional conductors described by Fermi liquid scattering theory and the fractional quantum Hall system at Laughlin filling fractions, described by the chiral Luttinger liquid formalism. We study the emission noise, its expansion in the temperature difference (focusing on the quadratic component) as well as the excess emission noise defined with respect to a properly chosen equilibrium situation. The behavior of these quantities are markedly different for the fractional quantum Hall system compared to Fermi liquids, signalling the role of strong correlations. We briefly treat the strong backscattering regime of the fractional quantum Hall liquid, where a behavior closer to the Fermi liquid case is observed.