Mr. Thomas Bell

PhD Candidate

Bose-Einstein condensates form when dilute gases are confined and cooled below a critical temperature. Confinement geometries with different strength and topology define unique transition temperatures, below which a useful superfluid phase condenses. The ongoing development of novel confinement geometries for condensates has expanded our fundamental understanding of the phenomenon and elucidated pathways toward engineering practical applications which harness their exotic superfluid properties. When appropriately prepared within suitable geometries, condensate superfluids enable various practical applications including inertial sensing, and fundamental studies of turbulence. Tom's research, overcomes several challenges associated with engineering those confinement geometries suitable for demonstrating various theoretical applications.

Spatial Light Modulation (SLM) technologies enable the experimental formation of reconfigurable optical dipole force confinement geometries suitable for demonstrating several proposed applications using Bose-Einstein condensates. Tom's research has focussed on developing experimental acousto-optic and micro-mirror based SLM technologies. Complementary numerical methods which improve our understanding of several fundamental phenomena have been developed, and experimental implementations for several future applications demonstrated numerically.

During Tom's candidature, substantial progress toward developing condensate inertial sensors was demonstrated using an acousto-optic SLM technology, an approach which relies on time-averaging. Rather than producing complete confinement geometries in one process, toroidal geometries were achieved through scanning a localised potential around a circular path. Provided the scan frequency was large, condensates were confined within the time-averaged geometry. Defining the fundamental requirements for producing time-averaged confinement represents one significant outcome from his thesis. Developing methods for correcting confinement non-uniformities using the observed density distributions represents another significant outcome. Those results together subsequently enabled the development of various novel micro-mirror SLM technology based atomtronic applications.

2019

Gauthier Guillaume et al, 2019
Science, 364, 6447, pp. 1264-1267

Adding energy to a system through transient stirring usually leads to more disorder. In contrast, point-like vortices in a bounded two-dimensional fluid are predicted to reorder above a certain energy, forming persistent vortex clusters.

2018

Rapidly scanning magnetic and optical dipole traps have been widely utilized to form time-averaged potentials for ultracold quantum gas experiments.

2016

Interferometric measurements with matter waves are established techniques for sensitive gravimetry, rotation sensing, and measurement of surface interactions, but compact interferometers will require techniques based on trapped geometries.

2014

McKay Parry Nicholas et al, 2014
Review of Scientific Instruments, 85, 8, pp. 86103

We describe a magnetic coil design utilizing concentrically wound electro-magnetic insulating (EMI) foil (25.4 μm Kapton backing and 127 μm thick layers). The magnetic coils are easily configurable for differentcoil sizes, while providing large surfaces for low-pressure (0.12 bar) water cooling.