1. Institute for Quantum Electronics, Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
2. James Watt School of Engineering, University of Glasgow, Glasgow G12 8LT, United Kingdom
3. Dipartimento di Scienze, Universita Roma Tre, Roma 00146, Italy
4. nextnano GmbH, Konrad-Zuse-Platz 8, München 81829, Germany
5. Dipartimento di Fisica “E. Fermi,” Universita di Pisa, Pisa 56127, Italy
6. Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, I-00185 Rome, Italy
7. IHP - Leibniz-Institut für innovative Mikroelektronik, Im Technologiepark 25, D-15236 Frankfurt (Oder) Germany