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Non-classicality as a source of computational power

Barros Henaut, Luciana; (2020) Non-classicality as a source of computational power. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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The objects of study of this thesis are the origins of the quantum computational speed- up. For the past three decades research in quantum foundations pointed to a few dif- ferent properties of quantum systems that could be linked to computational power. We start our study investigating the power of correlations, as it is intrinsically found in the measurement-based model of quantum computation. An important recent contribu- tion to the field showed that measurements on three-qubit GHZ states lead to universal classical computation. In that scenario, a client initially limited to compute only sums modulo-2 can deterministically evaluate a non-linear (NAND) function when control- ling measurements on a GHZ state. We were interested in achieving deterministic computation of maximally non-linear functions using the same type of resource. Another interesting result related to the computation of a NAND function using GHZ states shows that it is possible to achieve the same task with unitary transfor- mations performed on a single qubit. Differently than in the protocol that uses GHZ states, in the single-qubit one, non-locality and traditional forms of contextuality can- not be linked to the computational advantage. In this thesis, we address the question of which type of non-classicality gives us the same computational power in the single- qubit scheme. We analyse carefully chosen variations of the protocol in terms of Bell’s and Tsirelson’s bounds and detect a connection between reversibility in transformations and the computational capability of the system.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Non-classicality as a source of computational power
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10118742
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