laboratoire pierre aigrain
électronique et photonique quantiques
laboratoire pierre aigrain

Séminaire - 23 Novembre 2009

Yoan Léger <br class='autobr' />Ecole Polytechnique Fédérale de Lausanne (EPFL)
Manipulating Polaritons, from confinement to superfluidity.

During the last few years, research on microcavity polaritons has been considerably stimulated by the discoveries of Bose-Einstein condensation and superfluidity of polariton gases. The unique properties of these interacting bosons triggered many theoretical proposals for optoelectronic devices based on polaritons (such as the realization of polariton logic gates or switches).

Motivated by the control of microcavity polariton properties, we developed a non-destructive method to locally change the polariton potential in the microcavity. This allowed us to study the polariton dynamics in controlled environments.
As a first step towards the implementation of complex structures, we studied the 0d confinement of polaritons in cylindrical traps called mesas, their relaxation from the 2D barriers inside the trap and their dynamics.
In parallel, we work on the characterization of the superfluid transition of 2D polariton gases. As a matter of fact, above a critical density, a polariton gas changes into a superfluid characterized by a “cross-like” linear dispersion called Bogoliubov dispersion. We developed a four wave mixing experiment to probe the excitation spectrum of the polariton superfluid. Our results represent the first non-ambiguous evidence of this specific feature.