  The excitonic occupancy state of a single, nanowire-based, heterostructure
quantum dot is dynamically programmed by a surface acoustic wave. The quantum
dot is formed by an interface or thickness fluctuation of a GaAs QW embedded in
a AlGaAs shell of a GaAs-AlGaAs core-shell nanowire. As we tune the time at
which carriers are photogenerated during the acoustic cycle, we find pronounced
intensity oscillations of neutral and negatively charged excitons. At high
acoustic power levels these oscillations become anticorrelated which enables
direct acoustic programming of the dot's charge configuration, emission
intensity and emission wavelength. Numerical simulations confirm that the
observed modulations arise from acoustically controlled modulations of the
electron and electron-hole-pair concentrations at the position of the quantum
dot.
