Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 43: Quantum dots and wires: Optical properties II
HL 43.6: Vortrag
Donnerstag, 28. Februar 2008, 15:30–15:45, EW 201
Ultrafast electro-optical spin control in charged quantum dot molecules — •Jose M. Villas-Boas1, Sergio E. Ulloa2, Jonathan J. Finley1, and Gerhard Abstreiter1 — 1Walter Schottky Institut, Technische Universität München, Germany — 2Department of Physics and Astronomy, Ohio University, Athens, USA.
In this work we model the dynamics of a semiconductor quantum dot (QD) molecule using a density matrix formalism and we show that it is possible to coherently manipulate its final state by applying a laser pulse with appropriate intensity, polarization and detuning. We focus our attention on the case where we have one electron loaded in the QD molecule, which can be achieved either using a gate voltage or doping. By applying a laser pulse with different frequencies we show that we can selectively induce Rabi oscillations between several possible state configurations, as for example trion (charged exciton) in one dot or an indirect trion (electron in one dot and exciton in the other). These changes are induced by the coherent coupling between dots and fully controlled by external electro-optical means. Our model takes into account possible sources of decoherence, which allow us to discuss the potential and limitations of using such system for quantum information processing. We will also discuss the possibility of using pulsed gate voltages to control the final state, where we can bring adiabatically the levels in resonance and transfer the electron (hole) population to the other dot. JVB is supported by the Alexander von Humboldt Foundation and QD-molecule research is supported by DFG via SFB631 and Nanosystems Initiative Munich (NIM).