Thesis (MSc)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: A Magneto Optical Trap (MOT) is a configuration formed by three orthogonal pairs of counterpropagating
circularly polarized laser beams and a magnetic field gradient. A MOT is used to
cool, capture and trap large numbers of atoms in vacuum at very low temperature in K range.
In this thesis the development of an experimental setup for realising a MOT of 87Rb atoms
is presented. The atomic structure of Rb and the theoretical background of laser cooling and
magneto optical trapping was reviewed. The influence of rubidium background pressure in the
vacuum system, the laser beam size and the power and frequency on the number of the trapped
atoms were studied in literature. The trapping and repumping lasers were characterised experimentally.
Six circularly polarised trapping beams with equal power were formed and properly
aligned to intersect at the center of the trapping cell. Two optical setups were designed and exploited
to investigate and optimise the trapping beam polarisation. The repumping laser beam
was successfully aligned and colinearly combined into all the trapping beams. Three different
experimental setups for saturated absorption spectroscopy were developed. Saturated absorption
spectra showing the hyperfine structure of both 85Rb and 87Rb isotopes were measured
and are discussed. Using two saturated absorption spectroscopy setups, the frequencies of both
lasers were successfully locked to the trapping and repumping transitions of 87Rb respectively.
A rectangular trapping cell was designed and attached to the vacuum system. A pressure of
about 10¯7 mbar was achieved. The magnetic field coils were characterised and affixed on both
sides of the cell in an anti-Helmholtz configuration. Setups for imaging and quantification of the
87Rb atoms in the MOT were designed. Finally, the procedures for demonstrating a MOT are presented. In conclusion, the current status of the project is reported, with recommendations
for the future work. / AFRIKAANSE OPSOMMING: ’n Magneto optiese val (Magneto Optical Trap, MOT) is ’n konfigurasie wat gevorm word
deur drie ortogonale laserbundelpare, wat elk uit twee sirkelvormig gepolariseerde bundels met
teenoorgestelde voortplantingsrigtings bestaan, en ’n magneetveld gradient. ’n MOT word gebruik
om ’n groot aantal atome af te koel, te vang en vas te hou in vakuum by ’n baie lae
temperatuur in die K bereik. In hierdie tesis word die ontwikkeling van ’n eksperimentele
optelling vir die realisering van ’n MOT van 87Rb atome voorgelê. Die atoomstruktuur van Rb
en die teoretiese agtergrond van laser afkoeling en ’n magneto optiese val is hersien. Die invloed
van die rubidium agtergronddruk in die vakuumstelsel, die grootte van die laserbundels en die
laser drywing en frekwensie op die aantal gevangde atome is bestudeer uit die literatuur. Die
MOT-laser en die optiese pomplaser is eksperimenteel gekarakteriseer. Ses sirkelvormig gepolariseerde
MOT-laserbundels met gelyke drywings is gevorm en behoorlik belyn om in die middel
van die MOT-sel te kruis. Twee optiese opstellings is ontwerp en gebruik om die polarisasie van
die MOT-laserbundels te ondersoek en te optimeer. Die optiese pomplaserbundel is suksesvol
belyn en ko-liniêr ekombineer met al die MOT-laserbundels. Drie verskillende eksperimentele
opstellings vir versadigde absorpsie spektroskopie is ontwikkel. Versadigde absorpsie spektra
wat die hiperfyn struktuur van beide die 85Rb en 87Rb isotope toon is gemeet en bespreek.
Deur twee versadigde absorpsie spektroskopie opstellings te gebruik is die frekwensies van beide
lasers suksesvol gestabiliseer op die MOT- en optiese pomp-oorgange van 87Rb onderskeidelik. ’n
Reghoekige MOT-sel is ontwerp en aangesluit by die vakuumstelsel. ’n Druk van ongeveer 10¯7 mbar is bereik. Die magneetveld spoele is gekarakteriseer en weerskante van die sel gemonteer
in ’n anti-Helmholtz konfigurasie. Ten einde word die prosedures vir die demonstrasie van ’n MOT voorgelê. In die gevolgtrekking word daar verslag gedoen oor die status van die projek,
met aanbevelings vir toekomstige werk.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/85586 |
| Date | 12 1900 |
| Creators | Elnour, Huzifa Mohammed Ahamed Mohammed |
| Contributors | Steenkamp, Christine M., Rohwer, Erich G., Stellenbosch University. Faculty of Science. Dept. of Physics. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xv, 84 p. : ill (some col.) |
| Rights | Stellenbosch University |
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