[1] Dept. of Elec. Eng. and Comp. Sci., Massachusetts Inst. of Technology, Cambridge, MA, United States
[2] Francis Bitter Magnet Laboratory, Massachusetts Inst. of Technology, Cambridge, MA, United States
[3] Department of Physics, Massachusetts Inst. of Technology, Cambridge, MA, United States
[4] Div. of Eng. and Applied Sciences, Harvard University, Cambridge, MA, United States
[5] Department of Chemical Engineering, Massachusetts Inst. of Technology, Cambridge, MA, United States
[6] Mech. and Aerosp. Eng. Department, School of Engineering, University of California, Los Angeles, CA, United States
[7] Dept. of Elec. Eng. and Comp. Sci., Massachusetts Inst. of Technology, Cambridge, MA 02139-4307, United States