1. Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
2. The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
3. Institute for Quantum Optics, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
4. Center for Integrated Quantum Science and Technology (IQst), Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
5. GREMAN, UMR 7347 CNRS, INSA-CVL, Tours University, 37200 Tours, France
6. Materials Physics & Applications Division: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos New Mexico 87545, United States