1. Low Temperature Laboratory, Department of Applied Physics, Aalto University, PO
Box 15100, AaltoFI-00076, Finland
2. QTF Centre of Excellence, Department of Applied Physics, Aalto University, PO Box 15100, AaltoFI-00076, Finland
3. Department of Physics, Harvard University, Cambridge, Massachusetts02138, United States
4. Department of Physics, Nanoscience Center, University of Jyväskylä, JyväskyläFIN 40014, Finland
5. Department of Science and Industry Systems, University of South-Eastern Norway, PO Box 235, Kongsberg3616, Norway