1. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
2. Department of Applied Physics, Stanford University, Stanford, California 94305, USA
3. SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
4. PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA