In this project aspects of quantum information processing in self-assembled semiconductor quantum dots are investigated. First, the spin dynamics in spin light emitting diodes is studied with time-resolved magneto-optical spectroscopy. Second, the manipulation of the spin state in the quantum dots with new techniques is a major research area. Third, to be able to do this more efficiently, a new device that has longer storage times of the electrons in the quantum dots than the spin light emitting diode is fabricated.