1. Laser Physics Centre,
Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia
2. Institut für
Quantenoptik, Universität Ulm, D-89081 Ulm, Germany
3. Department of Physics, University of California Santa Barbara, Santa Barbara, California 93106, United States
4. School
of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
5. Institut
für Festkörperphysik, Universität Ulm, D-89081 Ulm, Germany
6. National Institutes for Quantum and Radiological Science and Technology (QST), 1233 Watanuki, Takasaki, Gunma 370-1292, Japan