Optical experiments in semiconductor heterostructures have been widely applied during the last few years to investigate the steady state behavior of 2-D systems in magnetic fields. The dynamics of these systems in the very short time scales received only little interest until very recently, when Stark have looked at the nonlinear dynamics of magneto-excitons in GaAsAlGaAs multiple quantum wells MQW. In this paper we report the observation of a transient oscillatory behavior of the magneto-exciton absorption. We show that these oscillations are absorption quantum beats, caused by a coherent superposition between two excited spin polarized excitons. This coherent state persists as long as the excitons exist, for a few 10s of picoseconds To our knowledge this is the first observation of absorption quantum beats in solids. We show that we can measure by these technique the Lande g factor of the electron and holes in semiconductors.
This article is from 'Organization of the Optical Society of America Photonic Science Topical Meeting Series. Volume 7. Quantum Optoelectronics Held in Salt Lake City, Utah on 11-13 March 1991,' AD-A253 823, p45-48.