1. ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
2. Institute of Physics, Faculty of Electrical Engineering and Information Technology, University of the Bundeswehr Munich, Neubiberg 85577, Germany
3. Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
4. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
5. Quantum Engineering and Computing Group, Raytheon BBN Technologies, Cambridge, Massachusetts 02138, United States
6. Department of Physics and Astronomy, The University of Manchester, M13 9PL Manchester, United Kingdom