Imaging a 1-electron InAs quantum dot in an InAs/InP nanowire
  Nanowire heterostructures define high-quality few-electron quantum dots for nanoelectronics, spintronics and quantum information processing. We use a cooled scanning probe microscope (SPM) to image and control an InAs quantum dot in an InAs/InP nanowire, using the tip as a movable gate. Images of dot conductance vs. tip position at T = 4.2 K show concentric rings as electrons are added, starting with the first electron. The SPM can locate a dot along a nanowire and individually tune its charge, abilities that will be very useful for the control of coupled nanowire dots. 
A. C. Bleszynski-Jayich, L.E. Froberg, M. T. Bjork, H. J. Trodahl, L.   Samuelson and R.M. Westervelt