[1] Chalmers Univ Technol, Dept Microtechnol & Nanosci, Quantum Device Phys Lab, SE-41296 Gothenburg, Sweden
[2] Politecn Milan, Dipartimento Fis, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy
[3] Univ Gothenburg, Sahlgrenska Acad, MedTech West, SE-40530 Gothenburg, Sweden
[4] Univ Gothenburg, Sahlgrenska Acad, Inst Neurosci & Physiol, SE-40530 Gothenburg, Sweden
[5] Univ Napoli Federico II, Dipartimento Fis, Via Cinthia, I-80126 Naples, Italy