1. Department of Nuclear Engineering; Kyoto University; Uji 611-0011 Kyoto Japan
2. CREST; Japan Science and Technology Agency (JST); Chiyoda 102-0075 Tokyo Japan
3. Quantum Science and Engineering Center; Kyoto University; Uji 611-0011 Kyoto Japan
4. Department of Electronic Science and Engineering; Kyoto University; Nishikyo 615-8510 Kyoto Japan