1. Department of Physics, QSO—Quantum Science Otago, and Dodd-Walls Centre for Photonic and Quantum Technologies, University of Otago, Dunedin 9016, New Zealand
2. Department of Physics and Dodd-Walls Centre for Photonic and Quantum Technologies, University of Auckland, New Zealand
3. School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom