This thesis studies the dynamics of Feshbach molecule production from a gas of ultracold spin polarised Fermi atoms. A magnetic field is used to vary the strength of the interaction between the atoms exploring the limits of weakly paired atoms and tightly bound diatomic molecules. A mean field approximation is used to study the thermodynamics and dynamics of the system. The two-body interaction is modelled using a separable potential that reproduces the near threshold behaviour of the system close to a Feshbach resonance. For atoms in the same internal state interactions occur in the p-wave, such that they have one quanta of relative orbital angular momentum (ℓ = 1). The presence of a magnetic field fixes a quantisation axis for this angular momentum, leading to a splitting of the resonance feature into three components. It is shown that in certain cases these components may be treated separately on both a two-body and thermodynamic level. Consequently the many-body dynamics are also treated as if these components are distinct. In order to study molecule production the gas is prepared in a state similar to the Bardeen-Cooper-Schrieffer (BCS) state in a superconductor. A linear sweep of the magnetic field through a Feshbach resonance is used to convert the weakly paired atoms into tightly bound molecules. The variation of the molecule production efficiency is studied as the initial temperature, density initial magnetic field and final magnetic field are varied. Also studied is the variation of molecule production as a function of the rate at which the magnetic field is varied. It is shown that high densities are needed to explore a range of initial magnetic fields and sweep rates.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:565787 |
| Date | January 2012 |
| Creators | Austen, L. A. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1338129/ |
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