1. Department of Electrical and Computer Engineering, University of Washington, Seattle, Washington 98195, United States
2. Department of Physics, University of Washington, Seattle, Washington 98195, United States
3. Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
4. The Charles Stark Draper Laboratory, Cambridge, Massachusetts 02139, United States
5. Institute for Nano-engineered Systems, University of Washington, Seattle, Washington 98195, United States