14 September 2000, 2 p.m.

Karel Král
(Dept. of Condensed Matter Theory)
Multiphonon processes in quantum dots

Abstract:
The effect of relaxation of electron energy in semiconductor quantum dots is important from the point of view of lasers, infrared photodetectors and the semiconductor realizations of the quantum computation basic elements. The contradiction between the expected phonon bottleneck effect and the observed fast electron energy relaxation can be explained by means of the multiphonon mechanism of the electronic relaxation. It appears that this mechanism has an influence on the line-shape of the optical transitions, on the width of the optical lines, as it depends on temperature and on the lateral size of the dot. The modulation in time of the photon echo signal is discussed.The Dynamical Cluster Approximation: Non-Local Correlations in the 2D Hubbard-Model