1. Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
2. Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
3. Department of Electrical Engineering and Information Technology, Kyushu Sangyo University, Fukuoka 813-8503, Japan
4. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
5. RIKEN Center for Emergent Matter Science, Wako 351-0198, Japan