Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 55: Quantum dots: Interaction with environment

HL 55.4: Talk

Wednesday, March 18, 2015, 15:45–16:00, EW 203

Signatures of Förster and Dexter transfer processes in two coupled quantum dots for linear and two-dimensional coherent optical spectroscopy — •Judith Specht, Andreas Knorr, and Marten Richter — Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany

An in-depth investigation of the spin-dependent exciton dynamics in coupled nanostructures driven by coherent, ultrafast laser pulses is crucial for future applications e.g. in the field of quantum information processing. Two-dimensional coherent optical spectroscopy techniques serve as a powerful tool to study the microscopic coupling processes and the underlying excitation pathways. We show theoretically that it is possible to distinguish the signatures of the two different Coulomb induced resonance energy transfer mechanisms: Förster and Dexter coupling, using double quantum coherence spectroscopy.

Förster transfer denotes a purely dipole-dipole mediated interaction which can either transfer or flip the spin state of the excited electron, whereas Dexter coupling describes a direct exchange of electrons between the nanostructures. The possible excitation transfer pathways are selected by the polarizations of the exciting laser pulses and the mutual orientations of the two quantum dots.

We show that spectroscopic signatures reveal the type of excitation transfer process and the limitations imposed on the optical selection rules in the non-linear response.