Quantum Kinetics in Transport and Optics of Semiconductors Nanoscale miniaturization and femtosecond laser-pulse spectroscopy require a quantum mechanical description of the carrier kinetics that goes beyond the conventional semiclassical Boltzmann theory. On these extremely short lengths and time scales the electrons behave like partially coherent waves. This monograph deals with the quantum kinetics for transport in low-dimensional microstructures and for ultrashort laser-pulse spectroscopy. The nonequilibrium Green function theory is described and used for the derivation of the quantum kinetic equations. Numerical methods for the solution of the retarded quantum kinetic equations are discussed and results are presented for quantum high-field transport and for mesoscopic transport phenomena. Quantum beats, polarization decay, and non-Markovian behaviour are treated for femtosecond spectroscopy on a microscopic basis.