1. Technische Physik, Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
2. Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, United Kingdom
3. ITMO University, St. Petersburg 197101, Russia
4. Department of Biochemistry, Universität Würzburg, D-97074 Würzburg, Germany
5. Science Institute, University of Iceland, IS-107 Reykjavik, Iceland
6. SUPA, School of Physics and Astronomy, University of St Andrews, Fife KY16 9AJ, United Kingdom