The experiment of Ref.426 was repea

The experiment of Ref.426 was repeated by Alphenaar et al.429 for much larger point contact separations (≈ 100 μm), allowing a study of the length scale for equilibration of edge channels at the 2DEG boundary. Even after such a long distance, no complete equilibration of the edge channels was found, as manifested by a dependence of the Hall resistance on the gate voltage used to vary the number of edge channels transmitted through the point contact voltage probe (see Fig. 90). As discussed in Section IV.A.2, a dependence of the resistance on the properties of the contacts is only possible in the absence of local equilibrium. In contrast to the experiment by van Wees et al.,426 and in disagreement with Eq. (4.20), the Hall resistance in Fig. 90 does not simply follow the smallest of the contact resistances of current and voltage probe. This implies that the assumption of fully adiabatic transport has broken down on a length scale of 100 μm.