1. Institute of Physics, University of Szczecin 1 , Wielkopolska 15, 70-451 Szczecin, Poland
2. Centre for Quantum Technologies, National University of Singapore 2 , 3 Science Drive 2, Singapore 117543, Singapore
3. Department of Physics, National University of Singapore 3 , 2 Science Drive 3, Singapore 117542, Singapore
4. MajuLab, CNRS-UCA-SU-NUS-NTU International, Joint Research Unit 4 , Singapore