1. Department of Applied Physics, Yale University, New Haven, CT 06520, USA.
2. QuTech and Delft University of Technology, 2600 GA Delft, Netherlands.
3. Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, Netherlands.
4. Área de Física Aplicada, Universidad Politécnica de Cartagena, E-30202 Cartagena, Spain.
5. Departamento de Física Teórica de la Materia Condensada C-V, Universidad Autónoma de Madrid, E-28049 Madrid, Spain.
6. Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
7. Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049 Madrid, Spain.
8. Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE 41296 Gothenburg, Sweden.