1. Institut für Experimentalphysik Universität Innsbruck Technikerstraße 25d 6020 Innsbruck Austria
2. Department of Physics and Atmospheric Science Dalhousie University Halifax Nova Scotia B3H 4R2 Canada
3. Institute of Applied Physics, Abbe Center of Photonics Friedrich Schiller University Jena 07745 Jena Germany
4. Institut für Festkörpertheorie Universität Münster Wilhelm‐Klemm‐Straße 10 48149 Münster Germany
5. Condensed Matter Theory, Department of Physics TU Dortmund Otto‐Hahn‐Straße 4 44227 Dortmund Germany
6. Fraunhofer Institute for Applied Optics and Precision Engineering IOF Center of Excellence in Photonics 07745 Jena Germany