Edge channels at ν=2/3 of the fractional quantum Hall effect are predicted to exhibit edge reconstruction [1], and thus consist of two counter propagating channels: A downstream channel of electrons and an upstream channel of 1/3 quasi-particles. Lack of experimental evidence of the predicted reconstruction was explained by taking interactions and impurities into account [2]. Accordingly, the ν=2/3 edge states consist of an upstream neutral mode and a downstream charge mode with two terminal conductance of 2/3*e^2/h, which was verified experimentally.

Here, we present results of measurements with evidence of the edge reconstruction, void of the effects of interaction and disorder, which were achieved in small enough dimensions. Conductance measurements were made in samples of ν=1 state in the bulk, with a region of variable length at ν=2/3 in its center (induced by a biased top gate). Current was injected from the ν=1 region (source), passed the ν=2/3 region, and was collected by the other ν=1 region (drain).

At long ν=2/3 regions, the two terminal conductance was 2/3*e^2/h – as expected. As the ν=2/3 was made narrower the conductance increased above the 2/3 quantized value and, at a length of 0.4μm, it approached e^2/h – suggesting, a downstream edge mode of electrons in the 2/3 narrow region, void of ‘mixing’ with the upstream 1/3 edge.

Moreover, and surprisingly, as the fractional filling in the narrow region was lowered to 1/3, a similar enhancement in the conductance appears; suggesting an existence of edge reconstruction also in the ν=1/3 state.  No such enhancement in narrow regions had been observed in integer fillings in the narrow region.