Actively Tuned and Spatially Trapped Polaritons
  We report active tuning of the polariton resonance of quantum well excitons in a semiconductor microcavity using applied stress. Starting with the quantum well exciton energy higher than the cavity photon mode, we use stress to reduce the exciton energy and bring it into resonance with the photon mode. At the point of zero detuning, line narrowing and strong increase of the photoluminescence are seen. By the same means, we create an in-plane harmonic potential for the polaritons, which allows trapping, potentially making Bose-Einstein condensation of polaritons analogous to trapped atoms possible. We demonstrate drift of the polaritons into this trap. 
R.B. Balili (1), D.W. Snoke (1), L. Pfeiffer (2), K. West (2)   (University of Pittsburgh (1), Bell Laboratories (2))