Browsing by Author "Mpofu, Kelvin Tafadzwa."

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Quantum analogues of classical optimization algorithms.
(2017) Mpofu, Kelvin Tafadzwa.; Konrad, Thomas.; Tame, Mark Simon.
This thesis explores the quantum analogues of algorithms used in mathematical optimization. The thesis focuses primarily on the iterative gradient search algorithm (algorithm for finding the minimum or maximum of a function) and the Newton-Raphson algorithm. The thesis introduces a new quantum gradient algorithm suggested by Professor Thomas Konrad and colleagues and a quantum analogue of the Newton-Raphson Method, a method for finding approximations to the roots or zeroes of a real-valued function. The quantum gradient algorithm and the quantum Newton-Raphson are shown to give a polynomial speed up over their classical analogues.
Quantum plasmonic sensing with application to HIV research.
(2020) Mpofu, Kelvin Tafadzwa.; Kruger, Hendrik Gerhardus.; Tame, Mark Simon.
The main goal of this thesis is to show how the use of quantum states of light in biosensing with surface plasmon resonance (SPR) gives an enhancement over using classical states. SPR is a highly sensitive technique for monitoring changes in the optical properties of a substance in the immediate vicinity of a sensor surface, which makes it very useful in biosensing and surface science research. We focus primarily on a bio-sensing SPR setup known as the Kretschmann con guration in which surface plasmons are excited using a bulk prism and a gold coated microscope slide. The excitation is performed by means of an evanescent eld arising from total internal re ection from the backside of the sensor surface. We show theoretically that using quantum states of light such as the Fock state, twomode squeezed vacuum and two-mode squeezed displaced state improves the precision in the estimation of kinetic parameters measured from the sensorgrams produced by the Kretschmann con guration. Quantum states of light allow us to measure the parameters more accurately in comparison to the use of classical states of light. We look at a theoretical application of quantum bio-sensing in an immobilized Bovine serum albumin (BSA) interaction with anti-BSA, a binding reaction between a phosphate-bu ered saline (PBS) solution that contains Bovine carbonic anhydrase and its inhibitor benzene-sulfonamide, and a HIV case study. In our HIV case study we look at the binding reaction between a variant of HIV-1 protease and nel navir which is an inhibitor. The thesis also looks at an experimental implementation of the Kretschmann con guration with light from a single-photon source and shows an enhancement in sensitivity. We use the spontaneous parametric down conversion process to generate our single photons which we use to study the binding kinetics of BSA on a gold slide. This experiment is done with the anticipation that it will be extended in future to a drug kinetics study with HIV protease as we look at drug development.