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Vortices in a Bose-Einstein Condensate
Since the advent of Bose-Einstein condensation in the dilute alkalis, there has been
considerable interest in observing effects in atomic condensates akin to the hallmark
effects associated with superfluidity and superconductivity. In particular, the study of
quantized vortices and vortex lattices represents an important connection between the
traditional ”super” systems such as liquid Helium and this new atomic system.
This thesis explores some of the first vortex experiments in a condensate of magnetically
trapped Rubidium-87. Single vortex lines and rings are created using a wavefunction
engineering technique, which is an ideal starting point to study the dynamical
behavior of vortices within the condensate. An entirely different approach of “intrinsic
nucleation” has been developed to create rapidly rotating condensates with large
amounts of vorticity. A novel variation of forced evaporation is used to simultaneously
cool and spin up an ultracold gas. In this way, condensates can be formed that contain
large, extraordinarily regular lattices of well over 100 vortices. Direct detection
of the vortex cores makes it possible to study the microscopic structure of the vortex
arrangements both at equilibrium and under dynamical conditions where severe applied
stresses distort the lattice far from its equilibrium configuration.
In conclusion, the techniques developed in this thesis have opened up a new area of
rotating condensate physics and, in the future, may lead to regimes of extreme rotation
and quantum Hall physics.