1. Applied Physics, University of Paderborn, Warburger Straße 100, 33098 Paderborn, Germany.
2. Max Planck Institute for the Science of Light, Günther-Scharowsky-Straße 1/Bau 24,91058 Erlangen, Germany.
3. Department of Physics, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Praha, Czech Republic.
4. Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest, Post Office Box 49, Hungary.
5. Centre for Engineered Quantum Systems, Department of Physics and Astronomy, Macquarie University, Sydney NSW 2113, Australia.