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Optical group of Semiconductor Nanostructures -polariton-quantum fluids

Responsable : Jacqueline BLOCH
Centre de Nanosciences et de Nanotechnologies
Modern epitaxial technologies allow for the realisation of semiconductor nanostructures with simultaneous confinement of the electronic states and of the light modes. This is the case of semiconductor microcavities, whose elementary excitations are microcavity polaritons. These are two-dimensional half-light half-matter quasi-particles arising from the strong coupling between quantum well excitons and photons in a planar Fabry Perot resonator.

Their mixed light matter nature provides polaritons with unprecedented fundamental properties. From their excitonic part, polaritons strongly interact both with themselves and with the thermal bath of phonons. From their photonic content, polaritons have a very small effective mass (10-5 the free electron mass) and can be directly excited and observed via their light absorption and emission. All these properties along with their composite boson nature make polaritons very attractive to achieve Bose-Einstein condensates (BEC) and to study quantum fluid effects in a solid state system at high temperatures (5-300K). Moreover, the properties of a polariton condensate, such as its density, phase and temporal and spatial coherence, can be directly accessed by well developed optical spectroscopy techniques in a large variety of structures and geometries.

The high crystallographic quality of the GaAs based microcavities along with the refined etching techniques developed at LPN, allow for the Bose condensation of polaritons in 2D, 1D and 0D structures, and open the way to the study of coherent macroscopic phases, superfluidity, Josephson oscillations, soliton formation, quantum turbulence studies, etc.