Selective Optical Charge Generation, Storage and Readout in a Single   Self Assembled Quantum Dot
  We report the investigation of a single quantum dot charge storage device. The device allows selective optical charging of a single dot with electrons, storage of these charges over timescales much longer than microseconds and reliable optical readout of the charge occupancy using a time gated photoluminescence technique. This device enables us to directly investigate the electric field dependent tunneling escape dynamics of electrons at high electric fields over timescales up to 4 us. The results demonstrate that such structures and measurement techniques can be used to investigate charge and spin dynamics in single quantum dots over microsecond timescales. 
D. Heiss, V. Jovanov, M. Caesar, M. Bichler, G. Abstreiter, J. J.   Finley