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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

Donnerstag, 14. März 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 Kuhn¹ — ¹Institut 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.