1. Research School of Physics, The Australian National University 1 , Canberra, ACT 2601, Australia
2. Centre of Excellence for Quantum Computation and Communication Technology, School of Physics, University of Melbourne 2 , Melbourne, VIC 3010, Australia
3. Air Force Research Laboratory, Sensors Directorate 3 , Wright-Patterson Air Force Base, Ohio 45433, USA
4. KBR 4 , 3725 Pentagon Blvd., Beavercreek, Ohio 45431, USA