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.