Abstract

A reconstructed edge model in the filling factor $2/3$ quantum Hall regime, consisting of two
co-propagating charged edge channels accompanied by neutral channels, accounts for recent experiments exhibiting a plateau at a diagonal conductance of $e^2/(3h)$ through a quantum point contact. However, a significant non-equilibrium noise found on the conductance plateau in experiments is puzzling because fully transmitted or reflected channels are not expected to contribute to shot noise. Here, we suggest a novel noise-gererating mechanism on the plateau associated with the interplay between charge and neutral modes. We show that at low temperatures, this mechanism leads to the Fano factor of $2e/3$, consistent with the experiments.