Direct visualization of the quantum vortex lattice structure, oscillations, and destabilization in rotating He-4

Quantum vortices are a core element of superfluid dynamics and elusively hold the keys to our understanding of energy dissipation in these systems. We show that we are able to visualize these vortices in the canonical and higher-symmetry case of a stationary rotating superfluid bucket. Using direct visualization, we quantitatively verify Feynman's rule linking the resulting quantum vortex density to the imposed rotational speed. We make the most of this stable configuration by applying an alternative heat flux aligned with the axis of rotation. Moderate amplitudes led to the observation of collective wave mode propagating along the vortices, and high amplitudes led to quantum vortex interactions. When increasing the heat flux, this ensemble of regimes defines a path toward quantum turbulence in rotating He-4 and sets a baseline to consolidate the descriptions of all quantum fluids.

Automated summary

This article demonstrates the visualization and quantification of quantum vortices in a stationary rotating superfluid bucket and verifies Feynman's rule. The researchers also induce different effects by adjusting the heat flux, providing a foundation for studying quantum turbulence in rotating He-4.