Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 48: Poster 2

HL 48.39: Poster

Donnerstag, 26. März 2009, 15:00–17:30, P2

Non-classical acoustic phonon states from the decay of optical phonons — •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

While in quantum optics non-classical states of photons, such as squeezed states, have already been intensively studied, their investigation in phonon systems is only at the beginning. Besides fundamental interest in quantum effects in interacting many-particle systems, well-prepared non-classical phonon states could have applications e.g. for phonon based communications between nanostructures.

Here we consider fluctuation and coherence properties of non-equilibrium phonons after optical excitation in quantum dots. The optical excitation is accompanied by the generation of coherent optical phonons. These phonons in turn decay into acoustic phonons, which are the subjects of our investigation. From studies in bulk semiconductors it is known that this decay may lead to the formation of squeezed acoustic phonon states. While in the bulk only optical modes with q = 0 can be generated, in quantum dots also modes with nonvanishing q occur, corresponding to spatially inhomogeneous displacement fields. In our calculations we analyze the spatio-temporal dynamics of the acoustic phonon distributions including their fluctuation properties resulting from the decay of coherent optical phonons in a quantum dot.