Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 71: Quantum Dots and Wires: Optical Properties

HL 71.9: Vortrag

Donnerstag, 10. März 2016, 12:00–12:15, H15

Decay and persistance of spatial coherence in laterally spaced quantum dots — •Paweł Karwat¹, Krzysztof Gawarecki¹, Tilmann Kuhn², and Pawel Machnikowski¹ — ¹Department of Theoretical Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland — ²Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany

Some experiments show that collective emission effects [1] play a role in the optical response of systems consisting two (or more) Quantum Dots (QDs), which suggests that they cannot be treated as ensembles of independent emitters. One of the interesting features observed in the experiment is the difference between the time resolved emission under quasi-resonant (optical transition to higher confined shells) and non-resonant (transition to wetting layer or bulk states) excitation. This suggests that spatial coherence, which is lost during carrier capture to the QDs, must be to some extent conserved during relaxation between confined states. In this contribution, we take into consideration the realistic system consisting of two horizontally placed InGaAs QDs, coupled not only to the acoustic phonon reservoir, but also to optical phonons. Using the method of collective modes, we study theoretically the relaxation of polarons in the system. In particular, we investigate the impact of polaron effects into the evolution of spatial coherence.

[1] P. Karwat, P. Machnikowski, Phys. Rev. B 91, 125428 (2015).