The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Coulomb blockade spectroscopy. When the tip is close to the nanowire dot, it dents the wavefunction Ψ(x) of the quantum state, changing the electron's energy by an amount proportional to |Ψ(x)| 2 . By recording the change in energy as the SPM tip is moved along the length of the dot, the density profile of the electronic wavefunction can be found along the length of the quantum dot.2

We use a scanning gate microscope (SGM) to characterize one-dimensional ultra-thin (diameter ≈ 30 nm) InAs/InP heterostructure nanowires containing a nominally 300 nm long InAs quantum dot defined by two InP tunnel barriers.Measurements of Coulomb blockade conductance vs. backgate voltage with no tip present are difficult to decipher. Using the SGM tip as a charged movable gate, we are able to identify three quantum dots along the nanowire: the grown-in quantum dot and an additional quantum dot near each metal lead. The SGM conductance images are used to disentangle information about individual quantum dots and then to characterize each quantum dot using spatially resolved energy-level spectroscopy.

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