1. CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
2. Johannes Gutenberg University Mainz, 55128 Mainz, Germany.
3. Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
4. Helmholtz-Institut Mainz, 55099 Mainz, Germany.
5. Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
6. Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081, China.
7. Department of Physics, University of California at Berkeley, Berkeley, CA 94720–7300, USA.