1. Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106-9560, USA
2. Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA and Center for Computational Quantum Physics, Flatiron Institute (a division of the Simons Foundation), 162 5th Avenue, New York, New York 10010, USA
3. Materials Department, University of California, Santa Barbara, California 93106-5050, USA