Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 12: Symposium Quantum optics in semiconductors I

HL 12.3: Fachvortrag

Dienstag, 28. März 2006, 12:15–12:45, HSZ 01

Quantum Optics of Excitons in Semiconductors — •Heinrich Stolz — Institut für Physik, Universität Rostock,

The quantum optical properties of excitons,the bound states of the electron hole system at low and moderate densities in semiconductors are determined by the interplay between the fermionic nature of their constituents and the interaction with the bosonic photon field. In semiconductors with reduced dimensionality we have in addition to take the breakdown of the k-selection rule due to the modified symmetry and due to the always present disorder into account. This leads to a large variety of effects, which go beyond those in normal atomic quantum optics.

In this talk, the properties connected with the spontaneous radiative decay of excitons will be considered in more detail. In a coherently driven state this leads to the phenomena of resonance fluorescence (RF), which in a 2d quantum well shows up as the driven specularly reflected light and the spontaneous radiation in arbitrary directions. In a real quantum well, the latter is superimposed by the disorder induced Rayleigh scattering. By doing optical homodyning of the resoannce fluorescence under quasi-monochromtic resonant excitation, the reflected light shows strong phase-dependend noise, in contrast to what is expected from the usual semiclassical picture. In the same range of excitation powers, the spectral shape of the RF changes dramatically by developing side wings similiar to the well known Mollow triplet in atomic RF. Both effects can be explained by the simple picture of an ensemble of two-level system. Applying in addition high spatial resolution, we are able to resolve RF from single exciton states and clarifiy their dependence on the disorder.