Thesis archive |
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Author: Dr Holger Wolff
Title: Femtosecond Ablation and Characterisation of Microfabricated Atom Chips
Completed: November 2009
Abstract: This thesis is focused on the application of a new microfabrication
technique, femtosecond laser ablation, for the atom chip construction and on the characterisation of
the physical and magnetic properties of microwire structures. Femtosecond ablation was demonstrated to efficiently remove submicron thick layers of metal for structural shape changes in a one-step procedure.
Link: Thesis (pdf) (3.7 MB) |
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Author: Dr Sven Teichmann
Title: High Harmonic Generation for Coherent Diffractive Imaging
Completed: November 2009
Abstract: This dissertation presents experimental work on a high-harmonic generation source and
coherent diffractive imaging. A novel and successful approach of employing harmonic emission that consists
of multiple harmonic orders and its utilization for coherent diffractive imaging is presented, and associated
results are discussed. This work may prove valuable particularly for time-resolved spectroscopy,
sources of soft x-ray and extreme-ultraviolet radiation, and imaging based on harmonic emission.
Link: Thesis (pdf) (9.3 MB) |
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Author: Dr Gopi Veeravalli
Title: Molecular Bose-Einstein Condensates and p-wave Feshbach Molecules of 6Li2
Completed: August 2009
Abstract: The main objective of the research described in this thesis is to probe the
manybody quantum effects in a strongly interacting Fermi gas using Bragg spectroscopy. An enriched
source of Lithium-6 atoms is used to probe these properties. The broad Feshbach resonance of the two lowest
hyperfine levels of 6Li at a magnetic field of 834G is exploited to precisely control the interactions between the atoms.
Link: Thesis (pdf) |
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Author: Dr Jurgen Fuchs
Title: Molecular Bose-Einstein Condensates and p-wave Feshbach Molecules of 6Li2
Completed: January 2009
Abstract: This thesis describes the production of molecular Bose-Einstein condensates (BEC) of 6Li2 dimers and binding energy measurements of p-wave Feshbach molecules formed in combinations of the
|F = 1/2,mF = +1/2⟩ (|1⟩) and |F = 1/2,mF = -1/2⟩
(|2⟩) states. The binding energies scale linearly with magnetic field detuning for all three resonances. The relative
molecular magnetic moments are found to be 113±7 μK/G, 111±6 μK/G and 118±8 μK/G for the |1⟩ - |1⟩, |1⟩ - |2⟩ and
|2⟩ - |2⟩ resonances, respectively, in good agreement with theoretical predictions.
Link: Thesis (pdf) |
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Author: Dr Mandip Singh
Title: A Magnetic Lattice and Macroscopic Entanglement of a BEC on an Atom Chip
Completed: December 2008
Abstract: The
research work presented in this thesis is classified in two major categories. The first part is focused on the development
and construction of a permanent magnetic lattice on an atom chip and the study of trapped atoms in the permanent magnetic
lattice potential. In the second part, a new experiment is proposed to create a macroscopic entanglement between the flux state
of a superconducting loop and a Bose-Einstein condensate (BEC) on a superconducting atom chip.
Link: Thesis (pdf) |
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Author: Dr Daniel White
Title: Nanostructured Optical Fibre for use as Miniature Surface-enhanced Raman Scattering Sensors
Completed: October 2008
Abstract: This thesis invesitigates the use of an optical fibre based SERS system. The fibres are based on
highly modified medical imaging fibres consisting of a fused bundle of single-mode fibres ("pixels") drawn in such a way
that each fibre maintains its position along the length of the bundle. A selective chemical etchant
is used to erode the cores of these fibres leaving an array of wells. By drawing the fibre until the spacing between the
cores is of the order of hundreds of nanometres, the etched structures are suitable for SERS after coating with a thin layer
of metal. As a practical demonstration of the use of the SERS fibres, experiments on the detection of glucose,
CEES (a simulant for the nerve agent HD mustard) and chlorsulphuron (a commonly used herbicide), were conducted.
Link: Thesis (pdf) |
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Author: Dr Tra My Do
Title: Femtosecond Nonlinear Coherent Spectroscopy of Carotenoids
Completed: September 2008
Abstract: In this thesis femtosecond spectrally resolved one- and two-colour four-wave mixing coherent spectroscopy
is used to study the population dynamics and coherence dynamics in two carotenoids, lycopene (with eleven conjugated carbon
bonds (C=C), n = 11) and spheroidene (n = 10), in n-hexane solution. This information could play an important role in elucidating the
light harvesting function of lycopene and spheroidene in the process of photosynthesis.
Link: Thesis (pdf) |
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Author: Dr Saeed Ghanbari
Title: Superfluid to Mott insulator quantum phase transition in permanent magnetic lattices
Completed: March 2008
Abstract: In this thesis we study quantum degenerate Bose gases at finite temperatures in optical and magnetic
lattices and in particular the superfluid to Mott insulator quantum phase transition. We investigate ultracold atoms with
the gauge P representation and a truncated number-state basis. In studying the many-body physics problems which involve
nonlinear terms in the Hamiltonian of the system, the gauge P representation gives more stable results and also the
sampling error is reduced, compared with the positive P representation. We consider a grand canonical ensemble of Bose gases
and use the Bose-Hubbard model which can describe the dynamics of ultracold atoms in periodic potentials such as optical and
magnetic lattices. In our calculations, we consider open boundary conditions.
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Author: Dr Heath Kitson
Title: Experiments on Ultracold Rb: Rydberg atoms and Rb2 molecules
Completed: January 2008
Abstract: This thesis presents experiments done in both 85Rb and 87Rb magneto optical traps.
Fluorescence techniques are employed for the initial characterisation of atom number, density, temperature, loading and collisional
rates in the trap. Spectroscopy of atomic energy levels over most of the optical spectrum is presented for 85Rb, using a
two-photon ionisation technique. The atomic nd states where n=6-42 are resolved over an energy range of 15,800 - 20,800 cm-1.
An additional broad series of peaks following the nd series is observed but their origin could not be identified.
Link: Thesis (pdf) |
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Author: Dr Falk Scharnberg
Title: Bose-Einstein Condensation in Micro-Potentials for Atom Interferometry
Completed: October 2007
Abstract: Recent developments in atom optics have led to new proposals for interferometers, where the
splitting takes place spatially. Magnetic and optical traps are both suited for this kind of interferometer if a well
defined and highly controllable trap is realised. In this thesis results from two experiments that in principle allow
the creation of such traps are presented.
Link: Thesis (pdf) |
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Author: Dr Craig Lincoln
Title: Multidimensional nonlinear femtosecond spectroscopy of biological molecules
Completed: July 2007
Abstract: The new technique of two-colour spectrally resolved photon echo spectroscopy, is applied to the
biological system carbonmonoxy myoglobin (MbCO). This study provides supporting evidence for the mechanics of the initial
steps involved in the light-induced photodissociation of MbCO to form deoxy-myoglobin. A number of photophysical
phenomena associated with the reaction are investigated.
Link: Thesis (pdf) |
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Author: Dr Shannon Whitlock
Title: Bose-Einstein condensates on a magnetic film atom chip
Completed: April 2007
Abstract: Atom chips are devices used to magnetically trap and manipulate ultracold and Bose-Einstein condensates
near a surface. In particular, permanent magnetic atom chips can allow very tight confinement and intricate magnetic field designs
circumventing technical current noise. Research described in this thesis is focussed on the development of a magnetic film atom chip,
the production of Bose-Einstein condensates near the film surface, the characterisation of the associated magnetic potentials
using rf spectroscopy of ultracold atoms and the realisation of a precision sensor based on splitting Bose-Einstein condensates
in a double-well potential.
Link: Thesis (pdf) |
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Author: Dr Xiaoming Wen
Title: Ultrafast spectroscopy of semiconductor nanostrucrures
Completed: April 2007
Abstract: The key to designing and utilising semiconductor quantum structures is a physical understanding
of the detailed excitation, transport and energy relaxation processes. This thesis reports investigations into the electronic
and optical properties of various semiconductor quantum systems using a variety of ultrafast techniques, including
up-conversion photoluminescence, pump-probe, photon echoes and four-wave mixing.
Link: Thesis (pdf) |
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