1. Centre for Quantum Computer Technology, School of Physics, University of New South Wales, Sydney 2052, Australia
2. Centre for Quantum Computer Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney 2052, Australia
3. Centre for Quantum Computer Technology, School of Physics, University of Melbourne, Melbourne 3010, Australia
4. Centre for Quantum Computer Technology, Department of Physics, The University of Queensland, St Lucia, Brisbane 4072, Australia