Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 54: Optical Properties
HL 54.2: Vortrag
Mittwoch, 28. März 2012, 11:15–11:30, EW 203
Zero-dimensional periodic array of polariton condensates — •Edgar Cerda-Mendez1, Dmitry Krizhanovski2, Klaus Biermann1, Maurice Skolnick2, and Paulo Santos1 — 1Paul Drude Institut for Solid State Physics, Berlin, Germany — 2Department of Physics and Astronomy, University of Sheffield, Sheffield, United Kingdom
Polaritons are quasiparticles arising from the strong coupling between excitons and photons in a semiconductor microcavity. Being dilute bosons, they show a transition to a non-equilibrium macroscopical single quantum state (condensate), at a critical density Nc. Polaritons inherit a long de Broglie wavelength from their photonic component, so Nc is low and condensation occurs at temperatures in the kelvin range. The condensate has extended length (L) and time coherence. In this work, we demonstrate the controlled fragmentation of an extended exciton-polariton condensate (L∼30 µm) in an (Al,Ga)As-based microcavity into a periodical array of zero-dimensional condensates of size <4 µm. Fragmentation is induced by the periodic potential created by the spatial interference of two surface acoustic waves (SAWs) of wavelength λSAW=8 µm. The SAWs modulates the exciton and microcavity energies forming potential minima, where polaritons can condense. The threshold of condensation is reduced by modification of the scattering process and spatial confinement of the polaritons, which reduces the local losses. Condensation in high orbital states produced by the periodic potential is also observed allowing to observe the screening of the acoustic potential by nonlinear polariton-polariton interactions.