1. CCSE, Japan Atomic Energy Agency, Kashiwa, Chiba 277-0871, Japan
2. Mathematical Science Team, RIKEN Center for Advanced Intelligence Project (AIP), Chuo, Tokyo 103-0027, Japan
3. Department of Physics, Saitama University, Saitama 338-8570, Japan
4. JST, PRESTO, Kawaguchi, Saitama 332-0012, Japan