Why a noninteracting model works for shot noise in fractional charge experiments

Abstract

A fractional quasiparticle charge is a manifestation of strong interactions in the fractional quantum Hall effect. Nevertheless, shot noise of quasiparticles is well described by a formula, derived for noninteracting charges. We explain the success of that formula by proving that in the limits of strong and weak backscattering it holds irrespectively of microscopic details in weakly and strongly interacting systems alike. The derivation relies only on principles of statistical mechanics. We also derive an approximate model-independent formula for shot noise in the regime of intermediate backscattering. The equation is numerically close to the standard `noninteracting' fitting formula but suggests a different physical interpretation of the experimental results. We verify our theoretical predictions with a shot noise experiment at the filling factor $3/5$.