Thesis defense of Alexander Kosarev

The present work is dedicated to the study of the ultrafast coherent dynamics of the excitonic complexes localized in semiconductor nanostructures. We consider the  optical control of the optical and spin coherence of the negatively charged excitons using the photon echo technique. In the first two chapters, we overview the basic knowledge of the research area and the experimental techniques. In the third chapter, we considered the freezing of the dephasing in the inhomogeneously broadened ensembles of InGaAs quantum dots driven by the application of a resonant control pulse with an area of multiple of 2π. The freezing of dephasing allows us to vary the timing of the photon echo by up to 5 ps, which even slightly exceeds the echo duration. In the fourth chapter, we consider the resident electron dynamics in the CdTe quantum well. Long-lived three-pulse photon echoes in combination with the pump-probe Kerr rotation allowed us to analyze comprehensively the resident electron dynamics since they are differently impacted by the hopping of the resident electrons between the different localization sites. From the data, we evaluate the hopping rate all-optically. In the fifth chapter, we demonstrate the long-lived three-pulse photon echoes from the ensembles of the InGaAs quantum dots. It allowed us to extend the coherent optical response by at least an order of magnitude. We show that the transverse g-factor of the heavy hole in the trion state strongly impacts the temporal evolution of the system, and therefore modifies the long-lived three-pulse photon echo signal.

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