## Electronic Theses and Dissertations

Spring 2019

#### Degree Name

Master of Science in Applied Physical Science (M.S.)

#### Document Type and Release Option

Thesis (open access)

#### Department

Department of Chemistry

Mark Edwards

Monique Aller

Ryan Fortenberry

#### Abstract

We extend previous theoretical investigations of the creation of quantized circulation states by stirring Bose-Einstein condensates (BEC) confined in racetrack" potentials. The previous study, {\em Producing Smooth Flow in Atom Circuits by Stirring}, used the Gross-Pitaevskii equation (GPE), which is valid at $T=0$ K. Here we use a non-zero temperature model based on the Zaremba, Nikuni, Griffin (ZNG) theory to simulate stirring racetrack BECs. The two main goals of this thesis are 1) to understand the effects of temperature on the production of circulation and 2) to understand the mechanism by which the circulation is excited. We find that it is possible to produce circulation at non-zero $T$ in much the same way as at absolute zero, and the consideration of thermal effects is important for determining the precise amount of circulation obtained by stirring for a fixed total number of atoms. We also present a case study of the mechanism by which stirring produces flow in the GPE model.

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