Higher order exciton correlations from six-wave mixing

Peter Kner

Siqiang Zhang, Wei Li, Kangkang Li +5 more

S. R. Bolton, U. Neukirch, D. S. Chemla +2 more

Summary form only given. The nonlinear optical response in semiconductors has traditionally been treated in a mean field approximation at the 2-particle level. Recent work, in particular comparisons of four-wave mixing (FWM) with microscopic theory, have demonstrated the importance of 4-particle correlations. Such experiments, however, are not optimally sensitive to correlations at the 6-particle level. In order to probe such six-particle correlations we compare the results of six-wave mixing (SWM) measurements with a detailed microscopic theory based on the dynamics controlled truncation scheme (DCT).

V. M. Axt, S. R. Bolton, U. Neukirch +2 more

Six-wave-mixing signals from a ZnSe quantum well are analyzed experimentally and with a microscopic density-matrix description using the dynamics-controlled-truncation scheme. For each physically distinct combination of polarizations of the exciting pulses, the spectrum of six-wave-mixing emission is measured as a function of time delay. The experimental results are compared with calculations performed at different levels of approximation. Although the leading order contributions to six-wave-mixing signals are of fifth order in the laser field, we show that there are significant signal components that are due to at least ${\ensuremath{\chi}}^{(7)}$ processes. The sensitivity of six-wave-mixing signals to high-order Coulomb correlations is demonstrated. Six-point density matrices are found to be indispensable for the interpretation of our experiments, while some details seem to indicate the involvement of even higher-order correlation functions. Furthermore, we find a remarkable dynamical decoupling of spectral signatures and the delay-time behavior after excitation with linearly polarized pulses.

Atsushi Hasegawa, T.E. Kishimoto, Yasuyoshi Mitsumori +2 more

T. Voss, Hans Georg Breunig, Ilja Rückmann +3 more

Coherently controlled six-wave-mixing experiments on a ZnSe single quantum well are performed with different polarizations of the excitation pulses to enable or disable the creation of a biexcitonic polarization. A significant contribution of the biexcitonic polarization and other two-pair correlations is observed in the signal which is mainly modulated with the exciton transition frequency. A microscopic theory based on the dynamics controlled truncation scheme including six-point correlations is able to reproduce the experimental results.