  Images of a single-electron quantum dot were obtained in the Coulomb blockade
regime at liquid He temperatures using a cooled scanning probe microscope
(SPM). The charged SPM tip shifts the lowest energy level in the dot and
creates a ring in the image corresponding to a peak in the Coulomb-blockade
conductance. Fits to the lineshape of the ring determine the tip-induced shift
of the electron energy state in the dot. SPM manipulation of electrons in
quantum dots promises to be useful in understanding, building and manipulating
circuits for quantum information processing.

Mesoscale and Nanoscale Physics;Materials Science