Charge tunneling in fractional edge channels

Abstract

We explain recent experimental observations on effective charge of edge states tunneling through a quantum point contact in the weak backscattering regime. We focus on the behavior of the excess noise and on the effective tunneling charge as a function of temperature and voltage. By introducing a minimal hierarchical model different filling factors, $\ensuremath{\nu}=p/(2p+1)$, in the Jain sequence are treated on equal footing, in presence also of nonuniversal interactions. The agreement found with the experiments for $\ensuremath{\nu}=2/3$ and $\ensuremath{\nu}=2/5$ reinforces the description of tunneling of bunching of quasiparticles at low energies and quantitatively defines the condition under which one expects to measure the fundamental quasiparticle charge. We propose high-order current cumulant measurement to cross-check the validity of the above scenario and to better clarify the peculiar temperature behavior of the effective charges measured in the experiments.