1. CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, P.R. China
2. CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, P.R. China
3. Hefei National Laboratory for Physical Science at Microscale, and Department of Physics, University of Science and Technology of China, Hefei, P. R. China