Device noise as a probe of electron motion in quantum dots at high magnetic fields

We study the noise characteristics of gated quantum dots in the edge state (ES) regime. For samples cooled in the dark, and with one or more ES transmitted through the dot, zero current voltage fluctuations, thought to result from the influence of charged defects on the confining potential of the dot, are observed. Increasing the height of the point contact barriers to the dot, all occupied edge states are ultimately localised within it, and discrete resistance switching or "telegraph noise" is then found to emerge. The switching is present in both illuminated and unilluminated devices, consistent with a model in which the noise results from an intrinsic effect, in which single electrons tunnel between different edge states localised within the dot.