Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 3: Focus Session: Electron-phonon interaction and ultrafast processes in semiconductors

HL 3.6: Topical Talk

Monday, March 11, 2013, 12:30–13:00, H13

The role of phonons for exciton and biexciton generation in a quantum dot driven by adiabatic rapid passage — •Tilmann Kuhn — Institut für Festkörpertheorie, Westfälische Wilhelms-Universität, 48149 Münster, Germany

The excitation of a quantum dot with chirped laser pulses provides a powerful tool for a robust preparation of quantum states. This process, known as adiabatic rapid passage, can be well understood using the concept of dressed states. Compared to an ideal few-level system interacting with a chirped light pulse, however, the dynamics in a quantum dot is strongly modified by the influence of acoustic phonons which may lead to dephasing and transitions between the dressed states and therefore deteriorate the adiabatic passage.

In this talk I will present a theoretical analysis of the role of phonons for the preparation of either exciton or biexciton states in a quantum dot. At low temperatures phonon emission leads to pronounced asymmetries in the exciton state preparation when changing the sign of the chirp. When using linearly polarized light, the fidelity of the exciton preparation may be additionally reduced by phonon-assisted biexciton generation. On the other hand, by suitably tailoring the pulse parameters the biexciton state can be selectively prepared by using either a two-photon resonance excitation or a two-color scheme.