Forward scattering probe of edge-state coupling in the quantum Hall regime- art. no. 153303

We report on magnetoconductance measurements of a submicrometer-wide constr iction in a two-dimensional electron gas with a tunable central gate. For n egative central gate biases, an edge channel loop forms around the central- gate potential hump and couples to reflected edge channels, opening a forwa rd scattering pathway. From the conductance contribution of this pathway we deduce that the transmission probability for tunneling between adjacent ed ge channels of different Landau levels is 0.5, corresponding to the strong- coupling limit, for a coupling region of only a few hundred nanometers in l ength.