Magnetoexciton Quantum Beats: Influence of Coulomb Correlations

We report four-wave-mixing experiments on the magnetoexciton manifold in semiconductor quantum wells using broadband femtosecond pulses. The four-wave-mixing signal exhibits a complex beat structure that reflects the anaharmonicity of the magnetoexciton ladder. From spectrally resolved four-wave-mixing experiments, we conclude that the different magnetoexciton transitions are coupled. We discuss the origin of the coupling.