Rapidly Expanding BEC Ring: Analog Cosmology in a Lab

I will describe an experiment and some theory of an expanding, ring-shaped Bose-Einstein condensate. The expansion redshifts and damps long wavelength excitations, as in an expanding universe. After expansion, energy in the radial mode leads to the production of bulk topological excitations---solitons and vortices---driving the production of a large number of azimuthal phonons and, at late times, causing stochastic persistent currents. These complex nonlinear dynamics, fueled by the energy stored coherently in one mode, are reminiscent of a type of "preheating" that may have taken place at the end of inflation. (Based on 10.1103/PhysRevX.8.021021.)