Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 37: Quantum Dots and Wires: Optical Properties III

HL 37.9: Vortrag

Mittwoch, 24. März 2010, 11:45–12:00, H15

Electrically controllable g-factor of single quantum dots and quantum dot molecules — •Thomas Eißfeller, Till Andlauer, and Peter Vogl — Walter Schottky Institut, TU München, 85748 Garching

We predict the exciton g-tensor of single self-assembled InAs/GaAs quantum dots and molecules of vertically coupled quantum dot pairs in an external magnetic and electric field. The calculations are carried out in terms of a detailed 3D electronic structure theory that includes strain, piezoelectric charges and an eight-band k.p envelope function model. The magnetic field is incorporated in a manifestly gauge-invariant manner. For zero effective electric field, we find a linear dependence of the exciton g-factor on the exciton energy for single quantum dots. Importantly, we predict a giant bias controlled exciton g-factor tunability for certain quantum dot shapes and compositions. This is in excellent agreement with recent experiments. Secondly, we present quantitative theoretical results for the bias controlled anisotropic exciton g-tensor of vertically coupled quantum dot pairs. We find a giant g-factor tunability for vertical magnetic fields and a very pronounced g-tensor anisotropy for horizontal magnetic fields. This g-tensor tunability is more robust for quantum dot molecules than for single quantum dots. These results indicate that quantum dot molecules are promising candidates for the realization of g-factor engineered qubit gates.