1. Department of Medical Engineering, University of South Florida, Tampa, Florida 33620, United States
2. Department of Physics, University of South Florida, Tampa, Florida 33620, United States
3. Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
4. Department of Materials Science & Nano Engineering, Rice University, Houston, Texas 77005, United States
5. Department of Chemistry, Rice University, Houston, Texas 77005, United States