Nonequilibrium flows and superfluid turbulence in dilute gas Bose-Einstein condensates

Project level: PhD, Honours

Dilute gas Bose-Einstein condensates (BECs) were experimentally observed for the first time in 1995, more than seventy years after their initial proposal by Einstein.  Like helium-4 below the lambda point, they exhibit the defining properties of a superfluid, such as frictionless flow and the quantisation of rotational flow through quantised vortices.  However an important difference with superfluid helium is that there exists a tractable microscopic theory for dilute gas BEC.  This means that many of the phenomena that have been qualitatively explained in superfluid helium can be studied in a much more rigorous manner in a dilute gas BEC.

This project will study the establishment of non-equilibrium flows of dilute gas BECs between spatial regions with different thermodynamics parameters, such as temperature and density.  The resulting dynamics will lead to the nucleation and subsequent dynamics of solitons and vortex dipoles, and will provide relatively simple steady-state situations in which to study two-fluid dynamics and the establishment of quantum turbulence. We will determine non-equilibrium phase diagrams in one-, two-, and three-dimensional configurations, which correspond to different types of long-range order, and hence will exhibit qualitatively different superfluid behaviour.