Chorafas Foundation Award 2012 - Levrat Jacques

"Through his work, (Dr.) Jacques Levrat produced seminal contributions to the promotion of quantum mechanical effects up to room temperature. His studies provide a detailed understanding of the physics of quantum fluids at room temperature."

Abstract: Since its prediction in 1996 by Imamoğlu and coworkers, the use of a non-equilibrium exciton-polariton condensate to produce an intense coherent light source referred to as a polariton laser has attracted a lot of interest in the whole physics community as it should allow the realization of ultralow threshold coherent light-emitters. Exciton-polaritons are admixed bosonic particles resulting from the strong coupling between a cavity photon and an exciton. Here we are interested in GaN-based planar microcavities. Thanks to the stability of excitons at room temperature in this system, polariton condensation has been observed at ambient conditions under optical excitation, paving the way toward the realization of the first electrically injected polariton laser. In the present work, a detailed analysis of the system properties is provided as well as the description of the mechanisms leading to the formation of polariton condensates and the key elements for the optimization of devices relying on such nonlinearities. In particular, the derivation of the polariton phase diagram provides a synthetic view of the role played by the parameters governing the condensation threshold.