1. Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
2. Centre for Quantum Computation and Communication Technology, School of Engineering and Information Technology, University of New South Wales, Canberra, ACT 2600, Australia.
3. Center for Quantum Information and Control, University of New Mexico, MSC07-4220, Albuquerque, NM 87131-0001, USA.
4. Institute of Engineering Innovation, School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan.
5. Centre for Quantum Computation and Communication Technology, School of Science, RMIT University, Melbourne, Victoria 3001, Australia.