  We demonstrate an in-situ technique to tune the emission energy of
semiconductor quantum dots. The technique is based on laser-induced atomic
intermixing applied to nanowire quantum dots grown using a site-selective
process that allows for the deterministic tuning of individual emitters. A
tuning range of up to 15 meV is obtained with a precision limited by the laser
exposure time. A distinct saturation of the energy shift is observed, which
suggests an intermixing mechanism relying on grown-in defects that are
subsequently removed from the semiconductor material during annealing. The
ability to tune different emitters into resonance with each other will be
required for fabricating remote quantum dot-based sources of indistinguishable
photons for secure quantum networks.
