1 Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
2 Department of Physics, University of California at Berkeley, Berkeley, CA, USA.
3 Department of Applied Physics, Stanford University, Stanford, CA, USA.
4 Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
5 Department of Physics, Stanford University, Stanford, CA, USA.
6 Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
7 Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
8 Collaborative Innovation Center of Advanced Microstructures, Nanjing, China.
9 National Institute for Materials Science, Tsukuba, Japan.
10 Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA. [email protected].
11 Department of Physics, Stanford University, Stanford, CA, USA. [email protected].
12 Collaborative Innovation Center of Advanced Microstructures, Nanjing, China. [email protected].
13 State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China. [email protected].
14 Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai, China. [email protected].
15 Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. [email protected].
16 Department of Physics, University of California at Berkeley, Berkeley, CA, USA. [email protected].
17 Kavli Energy NanoSciences Institute at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory, Berkeley, CA, USA. [email protected].