Generating and controlling coherent states based on tailored wavepackets in a solid
Ultrafast Dynamics: Controlling collective states (ConCollStat)
Our research in the field of generating and controlling coherent states is based on the preparation of tailored wavepackets in a solid. The generation process is of fundamental interest itself, since it allows to generate a well-defined non-equilibrium state of the crystal lattice.  Time-resolved x-ray diffraction is the major experimental tool for such observations. The propagation and decay of phonon wavepackets allows to study fundamental interactions of the crystal lattice as well as correlations to charge and orbital order effects, e.g. in multiferroic materials.  Such wavepackets may even constitute new excitations which can lead to the development of novel photo-acoustic devices.  In the framework of HZB we develop a novel experimental station for time-resolved x-ray diffraction using a MHz laser system.  Our future setup will provide a versatile experimental chamber for diffraction experiments in various geometries in a broad temperature range.
Figure 1 Coherent acoustic phonon wavepacket propagating from the optically excited transducer (left side) into the substrate (middle and right). The modulation of the crystal lattice constant of the substrate leads to additional x-ray diffraction peaks that allow to monitor the propagation of the wavepacket.
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