1. Interdisciplinary Center for Quantum Information Zhejiang Province Key Laboratory of Quantum Technology and Device State Key Laboratory of Silicon Materials Department of Physics Zhejiang University Hangzhou 310027 China
2. Department of Chemistry Nagoya University Nagoya 464‐8602 Japan
3. Arts and Sciences NYU Shanghai Shanghai 200122 China
4. NYU‐ECNU Institute of Physics at NYU Shanghai Shanghai 200062 China
5. Department of Physics Osaka University Toyonaka 560‐0043 Japan
6. Department of Physics University of California at Berkeley Berkeley CA 94720 USA
7. Materials Science Division Lawrence Berkeley National Laboratory Berkeley CA USA
8. Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory Berkeley CA 94720 USA