My research is primarily concerned with the quantum nature of things - exploring the quantum world, and understanding quantum physics to make it useful for new technologies. I work in the fields of quantum information, quantum computation, quantum communication, quantum measurement, quantum control, and coherent control of semiclassical systems.
The Quantum Optics and Information Laboratory pursues work in these areas independently and in collaboration with colleagues at Griffith University, The University of Queensland, around Australia, and internationally. We are part of an international consortium exploring Optical Quantum Computing, part of an ARC Discovery project on Controlling Quantum Technology, and we form the Optical Quantum Information Program of the multi-institution ARC Centre of Excellence for Quantum Computer Technology (CQCT).
Recent experiments during my time at the University of Queensland have involved all-optical quantum information protocols. In particular, I have demonstrated a controlled-NOT gate for quantum computing. This gate has been characterized using quantum process tomography to map out its operation, and works with > 90% fidelity. Other experiments include the construction and characterization of a device to perform quantum nondemolition (QND) measurements on a qubit. This QND measurement can be varied in strength to perform weak measurements, which are useful for investigating complementarity and understanding the nature of measurement in quantum mechanics.
Previously, I have worked on coherent optical control of the quantum state of ensembles of ions in a solid matrix, and the ultrahigh resolution spectroscopy of these systems. This includes the phase-dependent study of decoherence of ionic transitions during optical driving, translation of coherent, phase-sensitive, multiple-pulse techniques from NMR to optical spectroscopy of solids, the engineering of absorption lines to ~25 kHz in solids, laser stabilization to ~1 part in 1013 using high finesse cavities and narrow spectral features in solids, and understanding the dynamics of spectral hole burning frequency references. This work has now been extended to various applications in classical and quantum information processing using impurity-ion solids
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