Time-resolved tunneling in the quantum Hall regime

We have studied the quantum Hall effect in the mesoscopic regime by measuring in detail the scattering events between the two spin-resolved levels of the lowest orbital Landau level. Our sample consists of a micrometer-sized quantum dot that is weakly coupled to large two-dimensional electron gases. In a high magnetic field electron transport through the dot is regulated by a mixture of Coulomb blockade effects and Landau-level quantization. Some Coulomb blockade oscillations show switching as a function of time between two discrete conductance values. We show that each switch is a time-resolved measurement of a single electron tunnel event between two Landau levels. Upon increasing the magnetic field, the time between two tunnel events reaches values as large as 100 s, We explain our observations with a phenomenological model that describes the dot as a two-level fluctuator. Furthermore, we have studied Coulomb oscillations as a function of magnetic field. The period of these magneto-Coulomb oscillations depends strongly on the occupation of the Landau levels in the reservoirs.