Sommaire:

Polaritons, half-light half-matter mixed states arising from the strong coupling between excitons and photons in semiconductor microcavities, are composite bi-dimensional interacting bosons. They can manifest macroscopic quantum coherence effects at high temperatures (5-300 K) due to their very low mass. In particular, polaritons behave like a quantum fluid with specific properties coming from its intrinsic out of equilibrium nature, determined by the short polariton lifetime (some picoseconds). At the same time, microcavity polaritons, due to the strong non-linear polariton-polariton interactions inherited from their excitonic component, are very promising for the realization of integrated optoelectronic devices operating at the quantum level. In the first part of the talk, I will briefly review the superfluid and Cerenkov regimes in these systems, and I will discuss the formation of quantized vortex and dark solitons in a polariton quantum fluid interacting with a large obstacle. The possibility to generate vortex lattices in a confined geometry will be discussed. Finally, I will show how the non linear polariton-polariton interactions can be exploited to achieve for the first time quantum noise reduction on a light beam transmitted by semiconductor micropillar, relying on a Kerr-like effect. These results show the potential for the generation of non-classical states of light with these nanostructures. In the second part of the talk I will present our recent results on efficient room temperature single photon emitters based on core/shell colloidal semiconductor nanocrystals. In such structures, the competition between radiative and non-radiative recombination channels induces photoluminescence fluctuations between on and off states known as blinking. The shell engineering is a suitable strategy to control recombination paths and has been used to produce almost non-blinking nanocrystals, although accompanied by undesired increasing of multi-excitonic emission probability. By using asymmetric core/shell nanoparticles (dots-in rods) with a spherical CdSe core surrounded by a rod-like CdS shell, blinking effects, multi-excitonic emission and polarization of the emitted photons can be separately controlled by tuning the shell dimensions. This allows an unprecedented capability in radiative channels engineering, making dot-in-rods very efficient blinking-free sources of polarized single photons on-demand.

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Pour plus d'informations, merci de contacter Rousseau E.