Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 71: Exciton polaritons and their condensates (HL, jointly with TT)

HL 71.6: Talk

Thursday, March 14, 2013, 11:00–11:15, H2

Influence of disorder on the propagation of polariton BEC — •Martin Thunert¹, Helena Franke¹, Chris Sturm¹, Rüdiger Schmidt-Grund¹, Alexander Janot², Bernd Rosenow², and Marius Grundmann¹ — ¹Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig — ²Universität Leipzig, Institut für Theoretische Physik, Brüderstr. 16, 04103 Leipzig

We report on the influence of disorder effects on the propagation of exciton-polariton Bose-Einstein condensates (BEC) in a ZnO-based bulk planar microcavity (MC). Due to their composite nature, the spatial distribution is affected by electronic (inhomogeneous carrier distribution) as well as photonic (thickness fluctuations, rough interfaces) disorder. The energy(E)-k-space emission patterns of the condensate show in dependence on temperature (T) and detuning (Δ) two different regimes: 1) ballistic polariton propagation for low (T,Δ) values and 2) disorder effects for increasing (T,Δ) values, which are reflected by a fragmentation of the (E,k) emission patterns. This can be explained by interference of localized condensates or by propagating condensates with different discrete velocities determined by scattering events at the disorder potential. For each (T,Δ) parameter set increasing pump power causes an increase of the fragmentation parameter which is deduced quantitatively from the (E,k) emission patterns. A theoretical investigation shows that a non-equilibrium exciton-polariton condensate remains stiff at finite length scales only. This indeed suggests a scenario of fragmentation caused by the interplay of disorder and gain-loss of the condensate.