Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 55: Quantum Dots and Wires, Optical Properties IV: Spin

HL 55.1: Vortrag

Donnerstag, 25. März 2010, 14:00–14:15, H14

Effect of spin relaxation on the exciton dynamics in a charged quantum dot — •Eleftheria Kavousanaki and Guido Burkard — Department of Physics, University of Konstanz, Germany

We theoretically model the exciton dynamics in a semiconductor quantum dot doped with a single electron when the two lowest quantum dot levels are photoexcited by two circularly polarized femtosecond optical pulses in a pump-probe configuration. We calculate the differential transmission spectrum as a function of the time delay between the two pulses by using a density matrix formalism and treating intra-band relaxation with the Lindblad semigroup method. We take into account relaxation processes in which the electron relaxes into the lowest quantum dot level either with or without a spin flip and investigate the possibility for spin-dependent blocking of intra-band relaxation due to the presence of the ground state electron. We show that the differential transmission spectrum is initially dominated by the fast no-flip mechanism before the slower spin-flip processes start to contribute at longer time scales, which allows for the spin polarization of the ground state electron to affect the dynamics.