We have developed a technique for changing the slope of the potential at an edge. This controls how independent the various edge states are, and the degree of scattering between them. This enables us to determine how much of the current has been transferred between edge states by scattering, and hence to learn about which edge states exist for a given slope. A diagram of the device.
Black regions are gates, where electrons are excluded.
Current flows from source to drain, as shown. A scanning electron micrograph of the device. White regions are gates. The set of parallel gates lie on top of the edge states, and are biased so as to provide a gradually changing potential with the required slope.