1. School of Electrical Engineering & Telecommunications, The University of New South Wales, Sydney 2052, Australia
2. QCD
Laboratories, COMP Centre of Excellence, Department of Applied Physics, Aalto University, P.O.
Box 13500, 00076 Aalto, Finland
3. Centre for Metrology and Accreditation (MIKES), P.O. Box 9, 02151 Espoo, Finland
4. School
of Physics and Australian Research Council Centre of Excellence for
Quantum Computation and Communication Technology, The University of New South Wales, Sydney 2052, Australia
5. O.
V. Lounasmaa Laboratory, Aalto University, P.O. Box 13500, FIN-00076 Aalto, Finland