1. Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
2. Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
3. Institut für Quantenoptik, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany