Evidence of six-particle Coulomb correlations in six-wave-mixing signals from a semiconductor quantum well - art. no. 115303

Six-cave-mixing signals from a ZnSe quantum well ark analyzed experimentall y and with a microscopic density-matrix description using the dynamics-cont rolled-truncation scheme. For each physically distinct combination of polar izations of the exciting pulses, the spectrum of six-wave-mixing emission i s measured as a function of time delay. The experimental results are compar ed with calculations performed at different levels of approximation. Althou gh the leading order contributions to six-wave-mixing signals are of fifth order in the laser held, we show that there are significant signal componen ts that are due to at least chi ((7)) processes. The sensitivity of six-wav e-mixing signals to high-order Coulomb correlations is demonstrated. Six-po int density matrices are found to be indispensable for the interpretation o f our experiments, while some details seem to indicate the involvement of e ven higher-order correlation functions. Furthermore, we find a remarkable d ynamical decoupling of spectral signatures and the delay-time behavior afte r excitation with linearly polarized pulses.