1. Department of Physics and Astronomy and Purdue Quantum Science and Engineering Institute, Purdue University 1 , West Lafayette, Indiana 47907, USA
2. Department of Physics, University of Central Florida 2 , Orlando, Florida 32816, USA
3. Institut des Sciences Moléculaires, Université de Bordeaux, CNRS UMR 5255 3 , 33405 Talence Cedex, France