Electron g factor in quantum wells determined by spin quantum beats

Spin quantum beats are detected in GaAs/Al subx Ga sub1-x As quantum wells in a magnetic field perpendicular to the growth direction by picosecond time-resolved photoluminescence spectroscopy. We directly determine the electron Lande g factor as a function of well width from 1 to 20 nm with unprecedented accuracy which makes quantitative comparison with theory possible.