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Quantum state preparation in emitter- waveguide systems
Thesis (PhD)--Stellenbosch University, 2021.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2021
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| _version_ | 1867613751112368128 |
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| access_status_str | Open Access |
| author | Francis, Jason Tarunesh |
| author2 | Tame, M. S. |
| author_browse | Francis, Jason Tarunesh Tame, M. S. |
| author_facet | Tame, M. S. Francis, Jason Tarunesh |
| author_sort | Francis, Jason Tarunesh |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2021. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/123585 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:41:06.301Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/123585 Quantum state preparation in emitter- waveguide systems Francis, Jason Tarunesh Tame, M. S. Rohwer, Erich G. Stellenbosch University. Faculty of Science. Dept. of Physics. Guided photonic modes Quantum information Communication applications Wave guides Photon emission Nanophotonics UCTD Thesis (PhD)--Stellenbosch University, 2021. ENGLISH ABSTRACT: The interaction of emitters with guided photonic modes can be used to prepare useful states for quantum information and communication applications. Since the dynamics and emission of emitters are time-dependent, they are best studied using a continuous temporal-mode theory. The Heisenberg-Langevin equation, within the continuousmode formalism, is such an approach. Following this approach, we model a two-level emitter interacting with a waveguide. We then characterise the state prepared via the interaction by calculating various statistics. Of particular interest is the possibility of preparing a photon-added coherent (PAC) state; a nonclassical state exhibiting quadrature squeezing and a sub-Poissonian photonnumber distribution. Previous theoretical works have employed a single-mode treatment of PAC states, which is incompatible with our emitter-waveguide model. Thus, we first model PAC state pulses using a continuous-mode approach. We study the properties of a single-photon and coherent state wavepacket superimposed with variable temporal and spectral overlap. We show that, even without perfect overlap, the state exhibits a sub-Poissonian number distribution, second-order quantum correlations and quadrature squeezing for a weak coherent state. We also study the effects of propagation loss on the properties of PAC state pulses. We then build our emitter-aveguide model. The state of the emitter is studied by calculating the averages of its Pauli operators. When driven by a coherent state, the emitter exhibits Rabi oscillations associated with excitation and stimulated emission. Driving by a superposition of coherent states, for which a full-quantum model is needed, is also considered. Unlike a coherent state, the superposed coherent state incoherently drives the emitters initially in the ground and excited state. The waveguide state is then investigated by deriving expressions for the photon number and quadrature statistics for an arbitrary input field. When the emitter is driven by a coherent state, we find that sub-Poissonian photon-number statistics and quadrature squeezing do not occur simultaneously nor due to the same process. This suggests that a PAC state cannot be prepared via spontaneous nor stimulated emission of a two-level system. This in turn, suggests that neither process can be thought of as simply the action of a creation operator on the guided mode. Finally, we experimentally characterise the emission from nitrogen-vacancy (NV) centres in nanodiamond; a promising quantum emitter. We performed measurements of the second-order correlation function, fluorescence lifetime, and spectrum on four nanodiamonds. Combining the results, we infer that the nanodiamonds containing multiple NV-centres produce incoherent multi-photon light. One nanodiamond contained a single NV-centre, and is shown to be a suitable single-photon source. AFRIKAANSE OPSOMMING: Die interaksie van emitters met geleide fotoniese modusse kan gebruik word om nuttige toestande voor te berei vir kwantuminligting en kommunikasie-toepassings. Aangesien die dinamika en emissie van emittente tydsafhanklik is, kan dit die beste bestudeer word deur gebruik te maak van 'n deurlopende temporale modus teorie. Die Heisenberg-Langevin-vergelyking, binne die deurlopende modus-formalisme, is so 'n benadering. Na aanleiding van hierdie benadering modelleer ons 'n tweevlak-emitter wat interaksie met 'n golfgids het. Ons karakteriseer dan die toestand wat deur die interaksie voorberei is deur verskillende statistieke te bereken. Van besondere belang is die moontlikheid om 'n foton-toegevoegde samehangende (PAC) toestand voor te berei; 'n nie-klassieke toestand wat kwadratuurpersing vertoon en 'n sub-Poissoniese fotongetalverdeling. Vorige teoretiese werke het 'n enkelmodusbehandeling van PAC-toestande gebruik, wat onversoenbaar is met ons emittergolfgeleidingsmodel. Sodoende modelleer ons eers PAC- oestandsimpulse met behulp van 'n deurlopende modusbenadering. Ons bestudeer die eienskappe van 'n enkel-foton en koherente toestand golfpakket, bo-op met veranderlike temporale en spektrale oorvleueling. Ons toon aan dat die toestand, selfs sonder perfekte oorvleueling, 'n sub-Poissoniese getalverdeling, tweede-orde kwantakorrelasies en kwadratuur vertoon vir 'n swak samehangende toestand. Ons bestudeer ook die effekte van voortplantingsverlies op die eienskappe van PAC-toestandimpulse. Ons bou dan ons emitter-golfgidsmodel. Die toestand van die emittor word bestudeer deur die gemiddeldes van sy Pauli-operateurs te bereken. As dit deur 'n samehangende toestand gedryf word, vertoon die emittor Rabi-ossillasies wat verband hou met opwinding en gestimuleerde emissie. Bestuur deur 'n superposisie van samehangende toestande, waarvoor 'n volledige kwantummodel nodig is, word ook oorweeg. Anders as 'n samehangende toestand, dryf die boonste samehangende staat die emittente aanvanklik in die grond en opgewonde toestand. Die golfgeleiertoestand word dan ondersoek deur uitdrukkings vir die fotongetal en kwadratuurstatistieke vir 'n arbitrere invoerveld af te lei. Wanneer die emittor deur 'n samehangende toestand aangedryf word, kom ons agter dat statistieke van die sub-Poisson-fotongetal en kwadratuurdruk nie gelyktydig plaasvind nie en ook nie as gevolg van dieselfde proses nie. Dit dui daarop dat 'n PACtoestand nie deur spontane of gestimuleerde emissie van 'n tweevlakstelsel voorberei kan word nie. Dit dui weer daarop dat geen van die twee prosesse bloot beskou kan word as die handeling van 'n skeppingsoperateur op die geleide modus nie. Laastens doen ons eksperimentele kenmerking van die emissie van stikstof- vakaturesentrums (NV) in nanodiamante; 'n belowende kwantumstoot. Ons het metings gedoen van die tweede-orde korrelasiefunksie, fluoressensie-leeftyd en spektrum op vier nanodiamante. As ons die resultate kombineer, lei ons af dat die nanodiamante wat veelvuldige NV-sentrums bevat, onsamehangende multifotonlig produseer. Een nanodiamant bevat 'n enkele NV-sentrum, en dit word getoon dat dit 'n geskikte enkelfoton bron is. Doctoral 2021-06-03T05:51:16Z 2021-12-22T14:10:52Z 2021-06-03T05:51:16Z 2021-12-22T14:10:52Z 2021-12 Thesis http://hdl.handle.net/10019.1/123585 en_ZA Stellenbosch University xiii, 127 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Guided photonic modes Quantum information Communication applications Wave guides Photon emission Nanophotonics UCTD Francis, Jason Tarunesh Quantum state preparation in emitter- waveguide systems |
| title | Quantum state preparation in emitter- waveguide systems |
| title_full | Quantum state preparation in emitter- waveguide systems |
| title_fullStr | Quantum state preparation in emitter- waveguide systems |
| title_full_unstemmed | Quantum state preparation in emitter- waveguide systems |
| title_short | Quantum state preparation in emitter- waveguide systems |
| title_sort | quantum state preparation in emitter waveguide systems |
| topic | Guided photonic modes Quantum information Communication applications Wave guides Photon emission Nanophotonics UCTD |
| url | http://hdl.handle.net/10019.1/123585 |
| work_keys_str_mv | AT francisjasontarunesh quantumstatepreparationinemitterwaveguidesystems |