1. Quantum Information Science Group, Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
2. Department of Physics and Fitzpatrick Institute for Photonics, Duke University, Durham, North Carolina 27708, USA
3. Department of Electrical and Computer Engineering and Centre for Quantum Technologies, National University of Singapore, Singapore 117583, Singapore
4. Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA