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Title: The blue-detuned magneto-optical trap
Author: Jarvis, Kyle
ISNI:       0000 0004 7655 5053
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 2018
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It has been more than 30 years since the first demonstration of a magneto-optical trap (MOT) using sodium atoms. Since then the MOT has revolutionised the field of atomic physics by facilitating the emergence of a broad range of productive avenues of research using atoms prepared at low temperatures and high densities. This thesis describes the development of a novel kind of magneto-optical trap: the blue-detuned MOT. Unlike in all previous MOTs the light is blue detuned from atomic resonances and drives "type-II" transitions that have dark ground-state sub-levels. A discussion of the position-dependent and velocity-dependent forces experienced by an atom or molecule in a MOT is first used to consolidate recent theoretical work and, in particular, to introduce the concept of a blue-detuned MOT. The design and construction of an experiment that has been built to demonstrate a blue-detuned MOT using ⁸⁷Rb is described. A thorough characterisation of this novel MOT has been performed. At high magnetic field gradients, radiation-pressure-limited densities exceeding 10¹¹ cm⁻³ have been reached whilst temperatures are cooled below 30μK by the efficient and robust sub-Doppler cooling mechanisms. The maximum phase-space density measured is 6 x 10⁻⁶, which is higher than in most normal atomic MOTs, comparable to the best dark SPOTs, and a million times higher than that reported for red-detuned type-II MOTs. This makes the blue-detuned MOT particularly attractive for molecules where laser cooling and trapping always uses type-II transitions. For the first time, a study of trap loss due to ultra-cold collisions between atoms occurring in the presence of near-resonant blue-detuned light is undertaken. Finally, the experiment is used to demonstrate many new and unreported configurations of MOT for ⁸⁷Rb, showing that a comprehensive understanding of complicated MOTs is now possible, and presenting a clear direction for further research.
Supervisor: Tarbutt, Mike ; Sauer, Ben Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral