Exciton beats in GaAs quantum wells: bosonic representation and collective effects

We discuss light–heavy hole beats observed in transient optical experiments in GaAs quantum wells in terms of a free-boson coherent state model. This approach is compared with descriptions based on few-level representations. Results lead to an interpretation of the beats as due to classical electromagnetic interference. The boson picture correctly describes photon excitation of extended states and accounts for experiments involving coherent control of the exciton density and Rayleigh scattering beating.

Work supported by MEC of Spain under contract PB96-0085, by the Fundación Ramón Areces and by the U. S. Army Research Office under Contract Number DAAH04-96-1-0183.