Spin injection, spin transport and spin coherence

We discuss advances, advantages and problems of spintronics through the example of a semiconductor laser whose emission intensity and polarization are modulated by the spin orientation of electrons. We show that spin transport should be feasible at room temperature and present possible concepts and first results concerning spin injection at high temperatures. Finally, we describe the coherent dynamics of coupled electron and hole spins in a quantum mechanical picture and measure the magnetic field-induced dynamics of localized excitons in a 3 nm GaAs quantum well. The system is capable of performing a quantum controlled not operation (CNOT), which realizes a basic two-qubit operation of quantum information processing in a semiconductor nanostructure.