Spatially resolved manipulation of single electrons in quantum dots using a scanned probe

Single electrons in a quantum dot have been manipulated with a scanning force microscope. The scanning metallic tip was coupled capacitively to the electrons confined in a lithographically defined gate-tunable quantum dot at a temperature of 300 mK. Single electrons were made to hop on or off the dot by moving the tip or by changing the tip bias voltage owing to the Coulomb-blockade effect. Spatial images of conductance resonances map the interaction potential between the tip and individual electronic quantum dot states. Under certain conditions this interaction is found to contain a tip-voltage induced and a tip-voltage independent contribution. Alessandro Pioda, Slavo Kicin, Thomas Ihn, Martin Sigrist, Andreas Fuhrer, Klaus Ensslin, Andreas Weichselbaum, Sergio E. Ulloa, Matthias Reinwald and Werner Wegscheider, Phys. Rev. Lett. 93, 216801 (2004), cond-mat/0411264