Nonequilibrium noise and fractional charge in the quantum Hall effect

We study nonequilibrium edge state transport in the fractional quantum Hall regime at filling g=1/m. Tunneling of Laughlin quasiparticles between edges is shown to generate both current and voltage shot noise with a universal ratio of noise amplitudes given by (ge2/h)2. In the weak backscattering limit we predict a current shot noise satisfying Poisson statistics with charge ge, which should enable a direct measurement of the fractional charge of the quasiparticle. On resonance the quasiparticles tunnel in pairs and the effective charge entering the current shot noise becomes 2ge. © 1994 The American Physical Society.