Please forward to your groups and post in your area. – thanks Center for Excitonics Seminar Series Announcement Tuesday, May 10, 2011 3:00 PM RLE Conference Room: 36-428 Speaker: Benoît Deveaud-Plédran, Ecole Polytechnique Fédérale de Lausanne “Bose-Einstein condensates of polaritons: Vortices and superfluidity” Abstract The idea of a possible Bose Eintein condensation in the solid state has been explored since the beginning of the sixties with the hope to get transition temperatures much more accessible than the temperatures needed for the condensation of atomic vapors (less than 1µK for Rubidium). The advantage in solids is that people are trying to condense excitons (an electron-hole pair in a semiconductor) with a mass similar to that of an electron, i.e. four orders of magnitude less than a rubidium atom. The price to pay is the disorder inherent to any real solid state system as well as the limited lifetime of the quasiparticles. We are using exciton polaritons, quasiparticles made one half for excitons and one half from a confined photon. Polaritons are bosons with a mass five orders of magnitude lighter than an electron. Then, condensation at temperatures of the order of 300 K has been observed. The price to pay is the incredibly short lifetime of the polaritons : one picosecond. During this talk, I will detail our studies on the physical properties of polariton condensates. In particular, I will focus on the evidence for superfluidity through the observation of quantized vortices. I will show their time resolved behavior, and show the first direct evidence for half quantized vortices, a specialty of spinor condensates. Bio Benoit Deveaud-Plédran is a full professor in Physics at the Ecole Polytechnique Fédérale de Lausanne having received his Physics Engineering degree from the Ecole Polytechnique, Paris in 1974, his Masters degree in Optoelectronics from Rennes University in 1977, and his PhD from Grenoble University in 1984. Amongst his many awards and recognitions are the 1985 Young Researcher Award from Paris' Ministry of Defense, the 2004 Best Teacher Award from EPFL, and the 2009 Outstanding Referee Award from Physical Review Letters. He is a specialist in the optical spectroscopy of semiconductors with a particular dedication to ultrafast and coherent optical spectroscopy. Over the last few years his team has expanded the understanding of coherent optical spectroscopy by developing a whole ensemble of actively stabilized interferometers, able to perform spectral interferometry as well as a profound understanding of the physics of semiconductor microcavities. Light refreshments will be served The Center for Excitonics is an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science and Office of Basic