Regensburg 2010 – wissenschaftliches Programm
HL 60.36: Poster
Donnerstag, 25. März 2010, 18:00–20:00, Poster D1
Non-classical phonon states in bulk and quantum dot structures — •Jonas Daniels1, Tilmann Kuhn1, and Vollrath Martin Axt2 — 1Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster — 2Institut für Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth
Non-classical phonon states are of fundamental interest in the field of solid state physics. When optical phonons are generated, they may decay into a pair of acoustic phonons. This so-called Klemens decay channel is similar to the well known photon parametric down-conversion. For photons this leads to the creation of squeezed photon states. Analogously also in the present case squeezed acoustic phonon states emerge, i.e., the fluctuations of the acoustic phonons are smaller than the vacuum fluctuation. We study the spatio-temporal dynamics of the acoustic phonon distributions including the fluctuation and coherence properties in both GaAs bulk and quantum dot systems. In bulk systems the acoustic phonons stem only from the q=0 optical phonon mode and are spatially homogeneous. In contrast, in quantum dot systems also optical modes with nonvanishing q occur, corresponding to spatially inhomogeneous displacement fields. We find that while part of the generated acoustic phonon population leaves the dot, the squeezing mainly remains inside the dot region.