1. IQMT, Karlsruher Institute of Technology, Eggenstein-Leopoldshafen, Germany
2. PHI, Karlsruhe Institute of Technology, Karlsruhe, Germany
3. CETATEA, National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania
4. Faculty of Physics, Babeş-Bolyai University, Cluj-Napoca, Romania
5. INFN, Sezione di Roma, Roma, Italy
6. CNR, Istituto di Nanotecnologia, c/o Dip. Fisica, Sapienza Università di Roma, Roma, Italy
7. INFN Laboratori Nazionali del Gran Sasso, Assergi (AQ), Italy
8. Institut Quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, Canada