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Quantum information processing with multipartite entangled quantum systems
Thesis (PhD)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613785727959040 |
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| access_status_str | Open Access |
| author | Alexander, Byron Joseph |
| author2 | Tame, Mark Simon |
| author_browse | Alexander, Byron Joseph Tame, Mark Simon |
| author_facet | Tame, Mark Simon Alexander, Byron Joseph |
| author_sort | Alexander, Byron Joseph |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/129369 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:41:40.401Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/129369 Quantum information processing with multipartite entangled quantum systems Alexander, Byron Joseph Tame, Mark Simon Ozdemir, Sahin Kaya Stellenbosch University. Faculty of Science. Dept. of Physics. Quantum entanglement Quantum systems Quantum computing Quantum information processing UCTD Thesis (PhD)--Stellenbosch University, 2023. ENGLISH ABSTRACT: In this study we investigate the role of multipartite entanglement in quantum information processing by examining two important classes of entangled quantum states: the novel class of projected squeezed (PS) states and the established class of weighted graph states. We first introduce a protocol for generating PS states, which is characterized by unitary spin squeezing and post-selection of a novel quantum measurement, leading to an appreciable reduction in the state preparation time of the maximally entangled N-qubit Greenberger-Horne-Zeilinger (GHZ) state when compared to standard deterministic preparation by unitary transformations. We then employ the quantum trajectory method to reduce the computational complexity required to model the generation of N-qubit PS states in realistic experimental conditions with relevant decoherence channels. By evaluating the quantum Fisher information (QFI) and overlap fidelity with the GHZ state, we demonstrate that the class of PS states is a useful metro logical resource for sensing, that is scalable and resilient to the effects of environmental noise. We next consider the class of weighted graph states and their use as entangled resources for quantum sensing. In particular, we identify metrologically relevant entangled sub-classes that are uniquely characterized by their graph geometry. These sub-classes are shown to yield a sensing precision below the classical limit, approaching the Heisenberg limit. This demonstrates that a reduced weighting, compared to the full weighting required for standard graph states, is sufficient to produce favorable metrological results for certain sub-classes of weighted graph states. This has the potential to reduce the practical requirements in a physical setup. We find there is robustness to variation in the weights, both at the ideal weight of n and at smaller weights, demonstrating that the practical realization of graph state sensing is feasible and robust. Our main findings include closed-form analytic expressions of the quantum Fisher information for an arbitrary number of N qubits, as well as the optimal estimator variance for local Pauli measurements. AFRIKAANSE OPSOMMING: In hierdie studie ondersoek ons die rol van meerpartye-verstrengeling in kwantuminligtingsverwerking deur twee belangrike klasse van verstrengelde kwantumtoestande te ondersoek: die nuwe klasse van geprojekteerde skeeptoestande (PS-toestande) en die gevestigde klasse van geweegde grafiektoestande. Ons stel eers 'n protokol voor vir die opwekking van PS-toestande, wat gekenmerk word deur eenheid-spinversteuring en na-keuring van 'n nuwe kwantummeganisme, wat lei tot 'n merkbare verkorting in die voorbereidingstyd van die maksimaal verstrengelde N-qubit Greenberger-Horne-Zeilinger (GHZ) toestand in vergelyking met die standaard bepalende voorbereiding deur eenheidstransformasies. Ons maak dan gebruik van die kwantumbaanmetode om die berekeningskompleksiteit te verminder wat benodig word om die op-wekking van N-qubit PS-toestande in realistiese eksperimentele toestande met relevante ontvanklikheidskanale te modelleer. Deur die kwantumvisserinligting (QFI) en oorvloedige getrouheid met die GHZ-toestand te eval-ueer, wys ons dat die PS-klas 'n nuttige metrologiese hulpbron vir sensering is wat skaalbaar is en veerkragtig is teen die effekte van omgewingsruis. Daarna oorweeg ons die klas van geweegde grafiektoestande en hul gebruik as verstrengelde hulpbronne vir kwantumsensering. Vera! identifiseer ons metrologies relevante verstrengelde subklasse wat uniek gekenmerk word deur hul grafiekgeometrie. Daar word aangetoon <lat hierdie subklasse 'n senseringspresisie onder die klassieke limiet !ewer wat die Heisenberg-limiet benader. Dit toon <lat 'n verminderde gewig, in vergelyking met die voile gewig wat vereis word vir standaard grafiektoestande, voldoende is om voordelige metrologiese resultate vir sekere subklasse van geweegde grafiektoestande te produseer. Dit het die potensiaal om die praktiese vereistes in 'n fisiese opstelling te verminder. Ons vind <lat daar robuustheid is teen variasie in die gewigte, beide by die ideale gewig van n en by kleinere gewigte, wat aandui <lat die praktiese verwesenliking van grafiektoestand-sensering uitvoerbaar en robuust is. Ons belangrikste bevindinge sluit in geslote vorm analitiese uitdrukkings van die kwantumvisserinligting vir 'n willekeurige aantal N qubits, sowel as die optimale skattervariansie vir plaaslike Pauli-metings. Doctoral 2023-11-15T14:02:57Z 2024-02-20T09:09:28Z 2023-11-15T14:02:57Z 2024-02-20T09:09:28Z 2023-12 Thesis https://scholar.sun.ac.za/handle/10019.1/129369 en_ZA Stellenbosch University x, 97 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Quantum entanglement Quantum systems Quantum computing Quantum information processing UCTD Alexander, Byron Joseph Quantum information processing with multipartite entangled quantum systems |
| title | Quantum information processing with multipartite entangled quantum systems |
| title_full | Quantum information processing with multipartite entangled quantum systems |
| title_fullStr | Quantum information processing with multipartite entangled quantum systems |
| title_full_unstemmed | Quantum information processing with multipartite entangled quantum systems |
| title_short | Quantum information processing with multipartite entangled quantum systems |
| title_sort | quantum information processing with multipartite entangled quantum systems |
| topic | Quantum entanglement Quantum systems Quantum computing Quantum information processing UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/129369 |
| work_keys_str_mv | AT alexanderbyronjoseph quantuminformationprocessingwithmultipartiteentangledquantumsystems |