The Effects of Disorder on a Quasi-2D System of Ultracold Atoms

An ultra-cold gas of atoms can be used to create many different model Hamiltonians. When tightly confined in one spatial dimension, the gas can become effectively two-dimensional. At low temperature, a quasi-2D Bose gas undergoes a Berezinskii- Kosterlitz-Thouless phase transition to a superfluid, mediated by the binding and unbinding of vortex pairs. As disorder affects vortex transport properties, a slight amount of fine- grain disorder in the potential energy may alter the properties of this phase transition. We will present experimental observations of a 2D Bose gas of rubidium atoms in the presence of disorder created by a laser speckle field.