Carrier-diffusion-limited remote optical addressing of single quantum dots

We present a scheme for remotely addressing single quantum dots (QDs) by means of near-field optical microscopy that simply makes use of the polarization of light. A structure containing self-assembled CdTe QDs is covered with a thin metal film presenting sub-wavelength holes. When the optical tip is positioned some distance away from a hole, surface plasmons in the metal coating are generated which, by turning the polarization plane of the excitation light, transfer the excitation towards a chosen hole and induce emission from the underlying dots. In addition, our procedure gives valuable insight into the diffusion of photo-excited carriers in the QD plane that can put limits to the addressing scheme.