1. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
2. Department of Physics, Harvard University, Cambridge, MA 02138, USA.
3. Department of Physics, Northeastern University, Boston, MA 02115, USA.
4. Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA.
5. Ames National Laboratory, Ames, IA 50011, USA.
6. Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
7. Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
8. Department of Physics, National Cheng Kung University, Tainan 701, Taiwan.
9. Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA.
10. Department of Physics, Boston College, Chestnut Hill, MA, USA.
11. Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Colaba, Mumbai, India.
12. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
13. Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
14. Center for Nanoscale Systems, Harvard University, Cambridge, MA 02138, USA.
15. Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
16. Center for Quantum Frontiers of Research and Technology (QFort), Tainan 701, Taiwan.
17. Physics Division National Center for Theoretical Sciences, Taipei 10617, Taiwan.
18. Canadian Institute for Advanced Research, Toronto, Canada.