1. Department of Physics and Astronomy, University of San Francisco 1 , San Francisco, California 94117-1080, USA
2. Department of Physics, University of Houston 2 , Houston, Texas 77024-5005, USA
3. 3 Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario, Canada
4. 4 Department of Physics & Astronomy, University of Waterloo, Waterloo, Ontario, Canada