Localized, collective excitations in strongly interacting superfluids: Pseudovortices, vortices, solitons, and their physical implications

Localized excitations form under many conditions in superfluids. Magnetic fields induce vortices in superconductors, while an out-of-equilibrium superfluid can create solitons, vortex rings, and vortices as the system returns to equilibrium. These nonlinear phenomena impact many experimental observables, and can also reveal information about the underlying superfluid.;In this thesis I will address excitations in strongly interacting superfluids. First, I consider vortices which arise in high magnetic fields (for superconductors) and high rotation speeds (for neutral superfluids). Among the phenomena of interest, I will describe how vortex-like precursors can arise in the normal state of this system. I will show how these effects alter the behavior of quantum oscillations in superconductors, which may explain puzzling features of the high-Tc cuprates. Second, I will consider defects which arise from sudden perturbations of a superfluid. To do this I will discuss phase imprinting in ultracold, trapped Fermi gases, and identify a variety of defects that result. These defects relate to similar defects in superfluid helium, which are the components of quantum turbulence. I will also discuss why our numerical simulations using the time-dependent Ginzburg-Landau equation properly model the expected physical behavior. Finally, I will show how these defects, such as vortex rings and vortices, are highly transient with a complex but qualitatively understandable time evolution.