Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 18: Focussed Session: Strong Light Matter Coupling I

HL 18.5: Hauptvortrag

Dienstag, 23. März 2010, 11:15–11:45, H13

Spectroscopy and Thermodynamics of Ultracold Excitons in a Potential Trap — •Heinrich Stolz — Institut für Physik, Universität Rostock,18051 Rostock, Germany

The condensation of Bosons into the system ground state at sufficiently low temperature in thermal equilibrium is one of the most spectacular manifestations of the quantum nature of matter and was first realized for atoms in a potential trap. Due to the general nature of the arguments, this Bose-Einstein condensation should occur in any system of quasi-particles with integer spin, the most prominent example being excitons, bound electron-hole-pair excitations in semiconductors. Especially promising have been the yellow 1S exciton states in cuprous oxide, but, despite several experimental studies of dense exciton states in this material, none of these resulted in a clear demonstration of the existence of a Bose condensed state of excitons. Recently, we have developed a theory of the spatio-spectral luminescence of excitons in a confining potential that takes both the polariton nature of the excitons and the exciton-exciton interaction into account [1]. Experimental results from a new strategy for creating a dense exciton system at low temperatures in a potential trap will be discussed with respect to these predictions. [2] H. Stolz and D. Semkat, submitted to Phys. Rev. B, cond-mat. ArXiv:0912.2010(2009).