1. Department
of Electrical Engineering
and Computer Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
2. Singapore University of Technology and Design, 20 Dover Drive Singapore 138682,
Singapore
3. Department of Physics
and Astronomy, Vanderbilt University, Nashville,
Tennessee 37235,
United States
4. Materials
Science and Technology
Division, Oak Ridge National Laboratory, Oak Ridge Tennessee 37831-6064, United States
5. Institute of Atomic
and Molecular
Sciences, Academia Sinica, Taipei, 11529,
Taiwan