1. Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
2. Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, United States
3. Department of Physics and Astronomy, University of California, Los Angeles, California 90095, United States
4. Center for Quantum Science and Engineering, University of California, Los Angeles, California 90095, United States
5. Challenge Institute for Quantum Computation, University of California, Los Angeles, California 90095, United States
6. Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States