1. CNR-IOM Laboratorio Nazionale TASC, Basovizza SS-14, km 163.5, I-34012 Trieste, Italy
2. Department of Physics, University of Trieste, Trieste, Italy
3. Department of Physics, University of Ljubljana, Ljubljana, Slovenia
4. Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY
5. Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA