1. Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, United States
2. Department of Physics, Key Laboratory of Strongly-Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
3. Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
4. Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, United States