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Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 91: Poster Session: Quantum dots and wires: preparation & characterization & optical properties & transport properties

HL 91.15: Poster

Thursday, March 14, 2013, 16:00–20:00, Poster A

Impact of longitudinal acoustic phonons on the excitation of quantum dots driven by chirped laser pulses — •Sebastian Lüker1, Krzysztof Gawarecki2, Martin Glässl3, Anna Grodecka-Grad4, Doris E. Reiter1, Vollrath Martin Axt3, Paweł Machnikowski2, and Tilmann Kuhn11Institut für Festkörpertheorie, WWU Münster, 48149 Münster — 2Institute of Physics, Wrocław University of Technology, 50-370 Wrocław, Poland — 3Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth — 4Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark

We theoretically investigate the impact of phonons on the excitation of quantum dots (QD) driven by chirped (frequency-swept) laser pulses, referred to as adiabatic rapid passage (ARP). The QD is modeled in the strong confinement limit as a two-level system, which is coupled to longitudinal acoustic phonons via the deformation potential.

A chirped pulse drives the system adiabatically along the spectral branch of the dressed eigenstates. Without coupling to phonons this results in a robust population of the exciton state for positive as well as for negative chirps. Transitions between the dressed states can occur by emission or absorption of phonons, which reduces the fidelity of the ARP. Because absorption of phonons is negligible at low temperatures, an asymmetry with respect to the sign of the chirp appears.

We calculate the system dynamics using a fourth order correlation expansion and compare our results to a time-convolutionless method and to numerically exact path integral calculations.

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