{"id":{"repo_id":"exeter","oai_identifier":"oai:figshare.com:article/32058150"},"canonical_url":"https://search.dev.ndltd.org/etd/exeter/oai:figshare.com:article/32058150","repository":{"repo_id":"exeter","name":"University of Exeter","base_url":"https://api.figshare.com/v2/oai"},"display":{"title":"Geometry and Light in Quantum Optical Systems","abstract":"This thesis looks at a range of quantum optical system with an emphasis on the geometrical structure. We first consider two coupled systems, a pair of 2-level systems and pair harmonic oscillators, with specific couplings to the environment through a Lindblad master equation. We look at observables such as optical spectrum to see the complex eigenvalues of the non-Hermitian systems. We compare the difference between how the linear oscillator and the non-linear truncated system behave at the steady state to find a dissipative phase transition. Next we consider a light-harvesting reaction-center model consisting of a ring of donor atoms coupled to a central acceptor. By introducing the Lindblad master equation, we model the effect of dissipation and dephasing, while also adding static disorder through site-specific randomness. We find high transfer efficiencies when coupled with a photon due to the geometry of the system transferring the excitation through a dark-state mechanism. Additionally, we find ways to mitigate the effect of negative the disorder of the photon-donor coupling has on the transfer efficiencies. We then consider the double excitation subspace of the same light-harvesting system, looking at a range of localised and delocalised conditions, as well as the system coupling to an incident photon pair. Singleand double-excitation transfer efficiencies were calculated, of up to 99% and 50%, respectively. Finally we consider a tight-binding lattice with an imbalanced geometry, consisting of two coupled layers: one with nearest-neighbour coupling and the other with nearest-neighbour and next nearest-neighbour coupling. We find localised states concentrated on the edge of a lattice in the finite sized model, with energies corresponding to the turning points in the bulk of the continuum bandstructure.<p></p>","abstract_html":"This thesis looks at a range of quantum optical system with an emphasis on the geometrical structure. We first consider two coupled systems, a pair of 2-level systems and pair harmonic oscillators, with specific couplings to the environment through a Lindblad master equation. We look at observables such as optical spectrum to see the complex eigenvalues of the non-Hermitian systems. We compare the difference between how the linear oscillator and the non-linear truncated system behave at the steady state to find a dissipative phase transition. Next we consider a light-harvesting reaction-center model consisting of a ring of donor atoms coupled to a central acceptor. By introducing the Lindblad master equation, we model the effect of dissipation and dephasing, while also adding static disorder through site-specific randomness. We find high transfer efficiencies when coupled with a photon due to the geometry of the system transferring the excitation through a dark-state mechanism. Additionally, we find ways to mitigate the effect of negative the disorder of the photon-donor coupling has on the transfer efficiencies. We then consider the double excitation subspace of the same light-harvesting system, looking at a range of localised and delocalised conditions, as well as the system coupling to an incident photon pair. Singleand double-excitation transfer efficiencies were calculated, of up to 99% and 50%, respectively. Finally we consider a tight-binding lattice with an imbalanced geometry, consisting of two coupled layers: one with nearest-neighbour coupling and the other with nearest-neighbour and next nearest-neighbour coupling. We find localised states concentrated on the edge of a lattice in the finite sized model, with energies corresponding to the turning points in the bulk of the continuum bandstructure.&lt;p&gt;&lt;/p&gt;","abstract_has_math":false,"creators":["Oliver Fox (21041801)"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2026,"date_issued":"2026-04-20T00:00:00Z","date_published":"2026-04-20T00:00:00Z","updated_at":"2026-07-27T19:33:24Z","subjects":["quantum","quantum optics","quantum mechanics","nanophotonics"],"languages":[],"rights":["All rights reserved"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["10779/exe.32058150.v1"],"render_values":[{"text":"10779/exe.32058150.v1","href":null,"code":true}]}]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Oliver Fox (21041801)"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2026-04-20T00:00:00Z"]},{"key":"dc:relation","label":"Dc Relation","values":["https://figshare.com/articles/thesis/Geometry_and_Light_in_Quantum_Optical_Systems/32058150"]},{"key":"dc:type","label":"Dc Type","values":["Text","Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["quantum","quantum optics","quantum mechanics","nanophotonics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["All rights reserved"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["10779/exe.32058150.v1"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["This thesis looks at a range of quantum optical system with an emphasis on the geometrical structure. We first consider two coupled systems, a pair of 2-level systems and pair harmonic oscillators, with specific couplings to the environment through a Lindblad master equation. We look at observables such as optical spectrum to see the complex eigenvalues of the non-Hermitian systems. We compare the difference between how the linear oscillator and the non-linear truncated system behave at the steady state to find a dissipative phase transition. Next we consider a light-harvesting reaction-center model consisting of a ring of donor atoms coupled to a central acceptor. By introducing the Lindblad master equation, we model the effect of dissipation and dephasing, while also adding static disorder through site-specific randomness. We find high transfer efficiencies when coupled with a photon due to the geometry of the system transferring the excitation through a dark-state mechanism. Additionally, we find ways to mitigate the effect of negative the disorder of the photon-donor coupling has on the transfer efficiencies. We then consider the double excitation subspace of the same light-harvesting system, looking at a range of localised and delocalised conditions, as well as the system coupling to an incident photon pair. Singleand double-excitation transfer efficiencies were calculated, of up to 99% and 50%, respectively. Finally we consider a tight-binding lattice with an imbalanced geometry, consisting of two coupled layers: one with nearest-neighbour coupling and the other with nearest-neighbour and next nearest-neighbour coupling. We find localised states concentrated on the edge of a lattice in the finite sized model, with energies corresponding to the turning points in the bulk of the continuum bandstructure.<p></p>"]},{"key":"dc:title","label":"Title","values":["Geometry and Light in Quantum Optical Systems"]}]}],"canonical_facts":{"dc:creator":["Oliver Fox (21041801)"],"dc:date":["2026-04-20T00:00:00Z"],"dc:description":["This thesis looks at a range of quantum optical system with an emphasis on the geometrical structure. We first consider two coupled systems, a pair of 2-level systems and pair harmonic oscillators, with specific couplings to the environment through a Lindblad master equation. We look at observables such as optical spectrum to see the complex eigenvalues of the non-Hermitian systems. We compare the difference between how the linear oscillator and the non-linear truncated system behave at the steady state to find a dissipative phase transition. Next we consider a light-harvesting reaction-center model consisting of a ring of donor atoms coupled to a central acceptor. By introducing the Lindblad master equation, we model the effect of dissipation and dephasing, while also adding static disorder through site-specific randomness. We find high transfer efficiencies when coupled with a photon due to the geometry of the system transferring the excitation through a dark-state mechanism. Additionally, we find ways to mitigate the effect of negative the disorder of the photon-donor coupling has on the transfer efficiencies. We then consider the double excitation subspace of the same light-harvesting system, looking at a range of localised and delocalised conditions, as well as the system coupling to an incident photon pair. Singleand double-excitation transfer efficiencies were calculated, of up to 99% and 50%, respectively. Finally we consider a tight-binding lattice with an imbalanced geometry, consisting of two coupled layers: one with nearest-neighbour coupling and the other with nearest-neighbour and next nearest-neighbour coupling. We find localised states concentrated on the edge of a lattice in the finite sized model, with energies corresponding to the turning points in the bulk of the continuum bandstructure.<p></p>"],"dc:identifier":["10779/exe.32058150.v1"],"dc:relation":["https://figshare.com/articles/thesis/Geometry_and_Light_in_Quantum_Optical_Systems/32058150"],"dc:rights":["All rights reserved"],"dc:subject":["quantum","quantum optics","quantum mechanics","nanophotonics"],"dc:title":["Geometry and Light in Quantum Optical Systems"],"dc:type":["Text","Thesis"]},"updated_at":"2026-07-27T19:33:24Z"}