This paper presents a thorough theoretical treatment (with some bonus new experimental results) of our recent demonstrations of phase measurement algorithms which variously beat the standard limit and achieve the fundamental limit of precision. We show how to do this without resorting to entangled states, both with and without adaptive measurements.
We were (or more specifically, our theory collaborator Prof. Howard Wiseman was) invited to write a paper for IEEE Journal of Selected Topics in Quantum Electronics. Here we describe several of the experiments recently taking place in our (or more specifically, Prof. Geoff Pryde's) laboratory, of which Howard is an integral part. It discusses the recent work on phase measurement, with some bonus theoretical details, as well as touching briefly on some soon-to-be-published work on adaptive quantum state discrimination.
Following up our previous publication, here we theoretically prove and experimentally demonstrate a quantum control algorithm to measure an optical phase at the fundamental Heisenberg limit of precision without entangled states or adaptive mesurements. We also demonstrate a simplified adaptive protocol with accuracy surpassing standard techniques.
This post marks the day of my first publication in a scientific journal. And it just so happens to be in Nature. For those not in the know, Nature is one of the highest-tier multidisciplinary journals in the world (if not the highest-tier: ongoing competition with Science makes that perennially debatable). As you can imagine, I'm pretty chuffed about that.
In this work, we developed and experimentally demonstrated an algorithm for phase measurement utilizing techniques from quantum control and quantum computation to achieve efficiency at the fundamental limit, better than any classical method, without requiring quantum entanglement. A thousand thanks to my coauthors and colleagues who gave me the opportunity to be a leading part of this project.
This post marks the completion of my honours thesis, as part of my BSc. (Hons) degree. It was a pleasure to work and learn under the supervision of Prof. Geoff Pryde at Griffith University, in close collaboration with Ben Lanyon in the laboratory of Prof. Andrew White at The University of Queensland.
The project served as my introduction to the world of experimental photonic implementations of quantum information. The aim of the project was to attempt to combine two techniques—quantum nondemolition measurement, and unambiguous state discrimination. The project was successful insofar as the experiment reproduced what we expected to obtain theoretically, though considerably more work would have been required in order to achieve complete nondemolishing unambiguous state discrimination. The PDF of the thesis can be found here.
During my undergraduate studies I was invited to join the “Advanced Studies” stream of my Bachelor of Science. This involved doing a few reports on assorted research topics, culminating in a final project as an introduction to participating in scientific research. I did my project under Prof. John Dobson, investigating the potential suitability of using wavelet transforms to enhance the speed of numerical solutions of van der Waals forces in solid materials.
I took several wavelet transform families and types, and examined the outcomes of their application to the matrix representations of the two operators involved in the force calculations. This was only a preliminary study, so it's uncertain how applicable the results ultimately are. That said, I found that certain wavelet transformations make the matrices less dense and, thus, possibly easier to solve. The PDF of my project report can be found here.
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