Electron transport driven by moving quantum dots in distant quantum point contacts

Abstract

Using moving quantum dots defined by surface acoustic waves that allow us to observe correlated electron transport in micron-separated quantum point contacts (QPCs), we present evidence for electron transport efficiency change that occurs where the coupling between these QPCs is provided by a region of two-dimensional electron gas rather than a static quantum dot. It is found that, when the latter QPC is set beyond conductance pinch-off, sweeping the first QPC, the acoustoelectric current shows a triangular-shaped peak. On the other hand, as the first QPC defines the entrance barrier by applying a fixed voltage and the voltage applied to the latter QPC is varied, we observe a resonant peak in the acoustoelectric current that is correlated to the point where the swept-QPC conductance nearly pinches off. From a study of the experimental characteristics, we suggest that they may be associated with the energy level rearrangement in the multi-QPC system as a result of charging up by dynamic quantum dots with their neighboring two-dimensional electron gas reservoirs.