A quantum integrated light and matter interface

Nute, Jonathan (2017) A quantum integrated light and matter interface. PhD thesis, University of Nottingham.

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Abstract

A highly integrated device capable of interfacing light and matter on a chip is presented. 1e7 caesium-133 atoms are captured from a hot vapour into a magneto-optical trap held close to a chip-mounted single-mode fibre. Sub-Doppler optical molasses cools the atoms and transfers them into a tightly focused 18W vertical optical dipole trap which intersects a 30um void that has been laser etched through the single-mode fibre. Thus, the optically trapped atoms are tightly confined in the path of fibre-guided photons for maximum overlap. Such a system is capable of writing, reading and storing quantum information and clearly has massive implications for quantum information technologies. The device presented is adaptable, scalable and highly integrated making it the ideal building block for quantum computing.

Developments and modifications made to a system for producing ultracold samples of lithium-6, caesium-133 and mixtures thereof is also presented. Feshbach molecules have major applications in quantum computing, particularly in the modelling of complex many-body quantum systems. The large dipolar moment of the lithium-caesium Feshbach molecule is the largest of all the alkali dimers producing rich long-range anisotropic dipole-dipole interactions. By use of the broad Feshbach resonance situated at 834G we associate fermionic lithium-6 atoms into bosonic lithium-6-2 Feshbach molecules. Subsequent evaporative cooling drives a phase transition in the diffuse lithium gas to produce a molecular Bose-Einstein Condensate containing up to 1e4 atoms, the first to be produced in the UK.

This thesis documents the construction of the quantum integrated light and matter interface (QuILMI) in its entirety from inception to realisation. An enormous amount of work has gone into the design and subsequent development of various vacuum, laser and magnetic systems that work seamlessly in tandem via a programmable control system. The system is now in a position to demonstrate to the world that atom-photon coupling on a chip is the way forward.

For the lithium-caesium mixture experiment, a versatile dual-species oven has been meticulously designed, constructed and thoroughly characterised to replace one that significantly malfunctioned and harmed the experiment. The oven is capable of tuning the axial fluxes of lithium and caesium through several orders of magnitude via PID temperature controlled reservoirs. An array of fifteen 0.51mm diameter microtubes highly collimate the dual-species atomic beam such that little flux is wasted prolonging the life of both the source and the vacuum ion pumps. This source will return the system to its former glory such that the ultimate goal of realising ultracold lihtium-caesium Feshbach molecules can once again be pursued.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Hackermueller, Lucia
Lesanovsky, Igor
Subjects: Q Science > QC Physics > QC170 Atomic physics. Constitution and properties of matter
Faculties/Schools: UK Campuses > Faculty of Science > School of Physics and Astronomy
Item ID: 41595
Depositing User: Nute, Jonathan
Date Deposited: 12 Jul 2017 04:40
Last Modified: 12 Oct 2017 14:45
URI: http://eprints.nottingham.ac.uk/id/eprint/41595

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