Non-equilibrium Feshbach association of Fermionic 6Li atoms

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Simmonds, Guy (2020) Non-equilibrium Feshbach association of Fermionic 6Li atoms. MSc(Res) thesis, University of Nottingham.

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Abstract

In this thesis, an experiment capable of producing 105 6Li2 molecules at temperatures between 0.1-1 µK will be presented. By firstly loading 108 6Li atoms into a Magneto-Optical Trap (MOT) and transferring them to a far-red detuned optical dipole trap, 106 atoms are loaded at a temperature of 400 µK. Evaporative cooling techniques are used to further cool the cloud to the region of quantum degeneracy. Feshbach coils capable of producing fields up to 1200G are also implemented to exploit the broad Feshbach resonance between the |F = 1/2,mF = ±1/2> states of 6Li.

Through this Feshbach resonance the scattering length of the atoms can be tuned to allow atoms to associate, forming so called “Feshbach Molecules”. In the case of 6Li, this allows for Fermionic atoms to form bound Bosonic states. In experiments that utilize Feshbach molecules, adiabacity in their production is assumed, but is not always the case. By performing linear magnetic field sweeps from the BCS to the BEC side of the broad Feshbach resonance in 6Li, the conversion efficiency of atoms to bound molecules will be presented as a function of both the sweep rate and cloud temperature. Statistical tests comparing Landau-Zener and power law models of the BCS-BEC transition will be presented and comparison to experimental results discussed. The effect of the cut-off field of the sweep on molecule conversion efficiency will be presented and compared to numerical simulations.

Item Type: Thesis (University of Nottingham only) (MSc(Res))
Supervisors: Hackermuller, Lucia
Fernholz, Thomas
Keywords: lithium, ultracold atoms, quantum optics, Feshbach molecules
Subjects: Q Science > QC Physics > QC170 Atomic physics. Constitution and properties of matter
Q Science > QC Physics > QC251 Heat
Faculties/Schools: UK Campuses > Faculty of Science > School of Physics and Astronomy
Item ID: 60267
Depositing User: Simmonds, Guy
Date Deposited: 14 Sep 2023 13:51
Last Modified: 14 Sep 2023 13:51
URI: https://eprints.nottingham.ac.uk/id/eprint/60267

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