1. Center For Quantum Devices Niels Bohr Institute University of Copenhagen Copenhagen 2100 Denmark
2. Centre for Analysis and Synthesis Lund University Box 124 Lund 22100 Sweden
3. Sino‐Danish College (SDC) University of Chinese Academy of Sciences 380 Huaibeizhuang Huairou District, Beijing 101408 China
4. Department of Physics Budapest University of Technology and Economics and Nanoelectronics ‘Momentum’ Research Group of the Hungarian Academy of Sciences Budafoki ut 8 Budapest 1111 Hungary