1. Department of Physics, Harvard University, Cambridge, MA, USA.
2. Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA.
3. ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA.
4. Radboud University, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ Nijmegen, Netherlands.
5. Department of Physics, Korea University, Seongbuk-gu, Seoul, Republic of Korea.
6. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
7. Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.