Coulomb Blockade Imaging of Few-Electron Quantum Dots in a Magnetic Field

One-electron quantum dots are important candidates for quantum information processing. We have developed a technique to image electrons inside a quantum dot in the Coulomb blockade regime, using a scanning probe microscope (SPM) at liquid He temperatures (1). We have used this technique to image the last electron in the dot in a strong perpendicular magnetic field.dots are formed in a two-dimensional electron gas in a GaAs/AlGaAs heterostructure by surface gates. Images are obtained by recording the dot conductance while scanning the SPM tip above the dot. SPM Images show a ring of increased conductance about the center of the dot, corresponding to a Coulomb blockade peak in the dot conductance.observe changes in the shape and the size of the conductance rings with magnetic field. This is due to a combination of energy shifts and orbital changes of the electrons in the quantum dot. \newline (1) P. Fallahi \textit{et al,} Nano Letters 5, 223 (2005)