1. Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
2. Max Planck Institute for the Science of Light, Erlangen 91058, Germany
3. Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe 76128, Germany
4. Institut FEMTO-ST, Université de Bourgogne Franche-Comté, CNRS, 25044 Besancon Cedex, France
5. Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76021, Germany
6. Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6123, USA
7. Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA