Upgrades to a Rb-85 Atom Interferometer

Webber-Date, Alexander (2022) Upgrades to a Rb-85 Atom Interferometer. PhD thesis, University of Liverpool.

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Abstract

The use of atom interferometry in high-precision measurements has led to an increased interest in their applications for fundamental physics research. The possible investigation of dark-sector physics research motivated the building of an atom interferometer at the University of Liverpool. The interferometer utilises a drop configuration and uses a two laser system for trapping and driving two-photon transitions. The system traps ∼ 108 Rb-85 atoms and cools them to ∼15 μK using Doppler and polarisation gradient cooling. The Raman beams are generated using an acousto-optical modulator, and coherent control of atomic states has been presented by the observation of Rabi oscillations. Interferometry has been demonstrated by producing Ramsay fringes. These successes laid the foundation for building an upgraded interferometer capable of Doppler-sensitive measurements. A new interferometer was designed that incorporated a new main chamber with 23 viewports, allowing for greater optical access and larger beams. The larger beams enable more atoms to be trapped. Increased Raman beam size creates a flatter, more uniform wave-front. The cooling and Raman beams have been separated with the implementation of a high-power laser, that doubles the frequency of 30 W of 1560 nm light to 8 W of 780 nm, ×16 the amount of power previously available. A new optical system capable of launching atoms has been designed and partially built and tested. This also improves state selection and reduces sources of leaking light. A new Raman beam system was designed and investigated. This makes use of an Electro- Optical-Modulator to detune from resonance and reduce the likelihood of dephasing via single-photon transitions. To accommodate this, the Raman beam power was also improved with the implementation of tapered amplifiers. This system was partially tested. The possibility of using a dipole trap for further cooling has also been investigated.

Item Type:	Thesis (PhD)
Divisions:	Faculty of Science and Engineering > School of Physical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	16 Dec 2022 14:20
Last Modified:	18 Jan 2023 20:40
DOI:	10.17638/03165194
Supervisors:	Coleman, Jonathon Bowcock, Themis
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3165194