Dresden 2011 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 19: Quantum Gases: Miscellaneous
Q 19.2: Vortrag
Dienstag, 15. März 2011, 11:00–11:15, HÜL 386
Modulation of polariton condensates with acoustic periodic potentials — •Edgar Cerda1, Dmitryi Krizhanovskii2, Klaus Biermann1, Michiel Wouters3, Rudolf Hey1, Paulo Santos1, and Maurice Skolnick2 — 1Paul-Drude-Institut Berlin, Hausvogteiplatz 5-7, 10117 Berlin, Germany — 2University of Sheffield, Sheffield S3 7RH, United Kingdom — 3Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
Exciton-polaritons are particles formed by the strong coupling between light and excitons in a semiconductor microcavity with embedded quantum wells (QWs). Being composite bosons in the dilute limite with very low mass, they are prone to condensation. In this work, we use surface acoustic waves (SAWs) propagating in a microcavity structure with QWs to create a periodic potential for polaritons by modulating the cavity thickness and the QW energy band gap. The modulation is realised with a SAW of wavelength λSAW=8µm propagating along a non-piezoelectric direction ([100]) of a (001)-GaAs microcavity. We investigate the effects of SAWs on the spatial coherence properties of exciton-polariton condensates. By increasing the applied power, the SAW modulation reduces the coherence length Ly in a controlled manner until the extended state is fragmented into weakly interacting wires confined at the valleys of the SAW wavefronts with width equal to Ly=λSAW/2=4µm. The decrease of Ly is understood in terms of the reduction of the tunneling coupling between adjacent wires and in the case of OPO, also by the spatial modulation of the pump.