1. School of Nature Science, Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
2. Center for Quantum Information, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
3. Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
4. 3. Physikalisches Institut and Research Center SCOPE and Integrated Quantum Science and Technology (IQST), University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany