1. Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics University of Science and Technology of China Hefei 230026 China
2. CAS Key Laboratory of Microscale Magnetic Resonance University of Science and Technology of China Hefei 230026 China
3. Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei 230026 China
4. Experimentelle Physik III Technische Universität Dortmund 44221 Dortmund Germany