On the identification of intervalence-band coherences in semiconductor quantum wells

A theoretical analysis of intervalence-band coherences is presented. These optically created non-radiative coherences are generalizations of non-radiative coherences in atomic and molecular three-level systems. Whereas in three-level systems these coherences are the basis of important and well-established nonlinear effects, the interpretation of experimental evidence for such coherences in semiconductors needs to be supported by many-body theory. Based on the dynamics-controlled truncation formalism, the respective contributions of intervalence-band coherences and coherent biexcitonic correlations in time-integrated differential transmission spectroscopy is investigated. It is found that the contribution of the biexcitonic correlations to the observable heavy-hole-light-hole beats can be eliminated, either by reducing the light pulse duration or by choosing the central frequency of the light pulses at the heavy-hole exciton.