Exciton beats in GaAs quantum wells: bosonic representation and collectiveeffects

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 electrom agnetic interference. The boson picture correctly describes photon excitati on of extended states and accounts for experiments involving coherent contr ol of the exciton density and Rayleigh scattering beating. (C) 1999 Elsevie r Science Ltd. All rights reserved.