Origin and evolution of the multiply quantized vortex instability

Abstract

We show that the dynamical instability of quantum vortices with more than a single unit of circulation results from a superradiant bound state inside the vortex core. We then reveal a striking behavior of the system in the nonlinear regime. Counter to the expectation that the instability should produce well-separated vortices, the system evolves into a bound state of corotating singularities orbiting within a few healing lengths of each other, undergoing modulations in separation. During these modulations, kinetic energy is traded back and forth between sound waves and vortical degrees of freedom.