1. Center for Integrated Quantum Science and Technology (IQST) and 3. Physikalischen Institut, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany.
2. Sumitomo Electric Industries, Itami, Hyougo, 664-0016, Japan.
3. National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan.
4. Research Center for Knowledge Communities, University of Tsukuba, Tsukuba, 305-8550 Japan.
5. Max Planck Institute for Solid State Research, Stuttgart, Germany.