1. SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
2. Department of Physics, Technical University of Munich, 85748 Garching, Germany
3. Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
4. Theoretical Physics, Saarland University, 66123 Saarbrücken, Germany
5. Munich Center for Quantum Science and Technology (MSQCT), Schellingstraße 4, 80799 München, Germany
6. Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany and Max Planck Institute for the Science of Light, Erlangen, Germany