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Naniyil, Vineetha (2022) Dynamics of non-equilibrium 6Li Feshbach molecules via magnetic field ramp. PhD thesis, University of Nottingham.

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Abstract

In this thesis, the dynamics of Feshbach molecule formation via magnetic field ramp is investigated. The work presented in this thesis dealt with production and study of bosonic Feshbach molecule from fermionic 6Li atoms by quenching the magnetic field across the broad Feshbach resonance at 834.1 G. The fraction of atoms converted to Feshbach molecules is measured experimentally and the dependence of temperature and the rate at which the magnetic field is ramped during the process has been presented. The formation of Feshbach molecule via magnetoassociation of ultracold 6Li atoms close to quantum degeneracy is also explored in this thesis.

A new development in theoretical simulation of the dynamics of Feshbach molecules creation and extraction of the atom-molecule coupling coefficient is also detailed in this work. The first experimental measurement of the atom-molecule coupling coefficient at different temperatures of atomic cloud varies from 3.2 µK to 130 nK has been presented here. An enhancement of the atom-molecule coupling strength is observed as the atoms close to degeneracy and we find that a qualitative agreement between the experimental result and theoretically calculated value. The Landau-Zener transition describes the dynamics of Feshbach molecule formation at higher temperature. The enhancement of the atom-molecule coupling coefficient at lower temperature reveals the many-body coherence in the system, which is not captured by the conventional Landau-Zener model.

The dependence of molecule conversion as a function of mean density and the final magnetic field are also studied in this thesis. The dependence of magnetic field on the creation of Feshbach molecule shows a shift in the centroid of the error function, which is used to fit with the experimental data. The theoretical explanation of the shift from the Feshbach resonance has yet to be studied.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Hackermueller, Lucia Li, Weibin
Keywords:	Feshbach molecule, Magnetic field
Subjects:	Q Science > QC Physics > QC501 Electricity and magnetism
Faculties/Schools:	UK Campuses > Faculty of Science > School of Physics and Astronomy
Item ID:	68617
Depositing User:	NANIYIL, VINEETHA
Date Deposited:	02 Aug 2022 04:40
Last Modified:	02 Aug 2022 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/68617

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