Quantum optical modelling and experiments investigating the population evolution in atomic zinc and ytterbium-171 ions

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dc.contributor.advisorSteenkamp, Christine M.en_ZA
dc.contributor.advisorNeethling, Pieter H.en_ZA
dc.contributor.authorBester, Siannen_ZA
dc.contributor.otherStellenbosch University. Faculty of Science. Dept. of Physics.en_ZA
dc.date.accessioned2022-03-01T06:07:47Z
dc.date.accessioned2022-04-29T09:18:40Z
dc.date.available2022-03-01T06:07:47Z
dc.date.available2022-04-29T09:18:40Z
dc.date.issued2022-04
dc.descriptionThesis (MSc)--Stellenbosch University, 2022.en_ZA
dc.description.abstractENGLISH ABSTRACT: This project sets out to derive, adapt and apply the four state optical Bloch equations to two very different experimental scenarios which are studied in our research group. These include modelling the first transition i n t he resonance ionization o f z inc between t he1S0 state and the 3P1 states. This transition is an electric dipole allowed but spin forbidden transition which is pumped by a pulsed laser. The second application is to model the qubit transition in the hyperfine levels o f t rapped y tterbium-171 ions. T his transition occurs in the 2S1/2 term, between the F = 0 ground state and the F = 1 excited states and is thus a magnetic dipole allowed transition which is driven by microwave radiation. This model was successfully derived and used to simulate various experiments where the following parameters within the model were varied: the spontaneous decay rate, the Rabi frequency, the laser’s detuning, the collisional rate and the external magnetic field. The model was used to identify when, in the case of the resonance ionization of zinc, it was acceptable to use the classical rate equations to model the transition. With the specific broad bandwidth pulsed laser which drives the transitions, it was found that the optical Bloch equations reduce to the rate equations due to the light being incoherent at the atoms. This is modelled by fast decay of the coherences between states. However, if a narrow bandwidth laser was used, then the four state optical Bloch model with averaging over the pulse’s spatial profile a nd t he p ulse t op ulse v ariationo f t he R abi frequency would be necessary to model the transition. The model was also used to accurately predict Rabi oscillations in trapped ytterbium- 171 ions and the model was fitted t o e xperimental d ata f rom a n m easurement o f Rabi oscillations. It was found that the four state model fitted the data better than the two state model even under conditions when only one of the excited states are pumped significantly. It was shown that the decay that was seen in the data was due to both losing ions from the trap as well as decoherence due to collisions within the system.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Hierdie projek het ten doel om die optiese Bloch-vergelykings wat ‘n vier-toestand stelsel beskryf af te lei, aan te pas en toe te pas op twee beduidend verskillende eksperimente wat in ons navorsingsgroep ondersoek word. Dit sluit die modellering van die eerste oorgang in die resonans-ionisasie van sink atome in, tussen die 1S0 toestand en die 3P1 toestande. Hierdie oorgang is ‘n elektriese dipool-toegelate, maar spin-verbode oorgang wat deur ‘n gepulseerde laser gepomp word. Die tweede toepassing is om die qubit oorgang in die hiperfyn vlakke van vasgevangde ytterbium-171 ione te modelleer. Hierdie oorgang vind plaas in die 2S1/2 term, tussen die F = 0 grondtoestand en die F = 1 opgewekte toestande en is dus ‘n magnetiese dipool-toegelate oorgang wat deur mikrogolfstraling gepomp word. Hierdie model is suksesvol afgelei en gebruik om verskillende eksperimente te simuleer waartydens die volgende groothede in die model verander is: die spontane vervaltempo, die Rabi frekwensie, die verskil tussen die laser frekwensie en die resonans frekwensie, die botsingstempo en die eksterne magneetveld. In die geval van die resonans-ionisasie van sink is die model gebruik om vas te stel wanneer dit aanvaarbaar is om die klassieke tempovergelyking-model te gebruik om die oorgang te beskryf. Met die wye bandwydte van die spesifieke g epulseerde l aser wat d ie o organged ryf, i s d aar g evind d at d ie optiese Bloch-vergelykings vereenvoudig na die tempovergeslykings as gevolg van die beperkte koherensie van die lig wanneer dit die atome bereik. Dit word gemodelleer deur vin- nige verval van die koherensie tussen die toestande. As ‘n laser met ‘n smal bandwydte egter gebruik word, sal die vier-toestand optiese Bloch-vergelykings, met die neem van gemiddeldes oor die puls se ruimtelike profiel e n d ie p uls-tot-puls v ariasie v an d ie Rabi frekwensie, nodig wees om die oorgang te modelleer. Die model is ook gebruik om die Rabi ossilasies in vasgevangde ytterbium-171 ione akkuraat te voorspel en die model is gepas op data van ‘n eksperimentele meting vand Rabi ossilasies. Daar is gevind dat die vier-toestand modeld die data beter pas as die twee- toestand model, selfs onder omstandighede waar slegs een van die opgewekte toestande beduidend gepomp word. Daar is gewys dat die afname wat in die data gesien is die gevolg was van beide die verlies van ione uit die ioonval en die verval van die koherensie as gevolg van botsing in die sisteem.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentxi, 114 pages : illustrations (some color)en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/124538
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectQuantum optics -- Experimentsen_ZA
dc.subjectBloch equationsen_ZA
dc.subjectYtterbium ionsen_ZA
dc.subjectBloch oscillationsen_ZA
dc.subjectQuantum theory -- Mathematical modelsen_ZA
dc.subjectAtom interferometryen_ZA
dc.subjectUCTDen_ZA
dc.titleQuantum optical modelling and experiments investigating the population evolution in atomic zinc and ytterbium-171 ionsen_ZA
dc.typeThesisen_ZA
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