1. Beijing Key Laboratory of Quantum DevicesKey Laboratory for the Physics and Chemistry of Nanodevices and Department of ElectronicsPeking University Beijing 100871 China
2. Center for NanochemistryBeijing National Laboratory for Molecular Sciences (BNLMS)College of Chemistry and Molecular EngineeringPeking University Beijing 100871 China
3. School of Physics and Electronics, and Institute of Super‐microstructure and Ultrafast Process in Advanced MaterialsCentral South University Changsha 410083 China
4. Powder Metallurgy Research Institute and State Key Laboratory of Powder MetallurgyCentral South University Changsha 410083 China
5. Beijing Academy of Quantum Information Sciences Beijing 100193 China
6. Division of Solid State PhysicsLund University Box 118 S‐221 00 Lund Sweden