Direct imaging of electron transport within a quantum point contact

Much attention has been given to sub-1G/sub 0/ (=2e/sup 2//h) features in the transmission curve of a quantum point contact (e.g.: 0.5G/sub 0/, 0.7G/sub 0/). Explanations for this phenomenon have been attributed to many-body interactions such as the Kondo effect or the formation of spin polarized currents. We have used scanning gate microscopy to directly observe the local features of the transport associated with sub-1G/sub 0/ structures. Images taken with this technique reveal striking features such as weak localization induced within the constriction as well as the formation of self-consistent potentials in the QPC.