Inside Back Cover: Spectral broadening and population relaxation in a GaAs interfacial quantum dot ensemble and quantum well nanostructure (Phys. Status Solidi B 4/2011)

The cover image shows a two‐dimensional spectrum from a GaAs quantum well (QW) and interfacial quantum dot (QD) ensemble obtained using two‐dimensional Fourier transform spectroscopy (2DFTS). This is a three‐pulse four‐wave mixing technique with the enhancement of interferometric stabilization of the excitation pulse delays, which allows a Fourier transform of the pulse delays to be taken. Using this technique, Galan Moody and co‐workers (see pp. 829–832 ) are able to separate and isolate the spectral response of QW and QD excitons, measure the homogeneous linewidth in the presence of inhomogeneity, and measure relaxation and excitation exciton transfer rates between the QW and QD ensemble. Exciton–phonon coupling is investigated through temperature‐dpendent measurements of the QD homogeneous linewidth and the QW–QD population transfer. The results indicate that elastic exciton–phonon coupling dominates the QD thermal broadening, while the QW→QD relaxation rate is over an order of magnitude larger than that for QD→QW excitation.