[1] Univ Queensland, Sch Math & Phys, Ctr Engn Quantum Syst, Brisbane, Qld 4072, Australia
[2] Univ Innsbruck, Inst Expt Phys, A-6020 Innsbruck, Austria
[3] Heriot Watt Univ, Inst Photon & Quantum Sci, Sch Engn & Phys Sci, Edinburgh EH14 4AS, Midlothian, Scotland
[4] Truman State Univ, Dept Phys, Kirksville, MO 63501 USA