A Gas of Excitons: Moving and Trapping Electronic Quasi-Atoms – David Snoke
Date: Mon. September 20th, 2004, 12:30 pm-1:30 pmLocation: Rockefeller 221
An exciton is bound state of a free, negatively charged electron and a postively charged hole in a semiconductor. Excitons act in many ways like hydrogen atoms which can move through a semiconductor and interact with each other much like a gas of atoms. While often excitons have very short lifetime (a few picoseconds), we have developed methods to extend their lifetime by several orders of magnitude, up to 10 microseconds, so that they can travel hundreds of microns across a semiconductor structure. We can also apply a force to the excitons to cause them to move in the direction we want, and we can trap them in a harmonic potential with a well-defined volume. This opens the door to attempts to see Bose-Einstein condensation of excitons in a system completely analogous to atomic condensates.