1. Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan
2. Institute for Nano Quantum Information Electronics, The University of Tokyo, Tokyo 153-8505, Japan
3. Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg 79110, Germany
4. Laboratory for Integrated Micro Mechatronic Systems/National Center for Scientific Research-Institute of Industrial Science (LIMMS/CNRS-IIS), The University of Tokyo, Tokyo 153-8505, Japan