Quantum swirling of superfluid helium films

Circularly polarized third-sound resonances are used to drive up and drive down persistent flow states in the superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ film inside the resonator, analogous to swirling a classical fluid by agitation. The induced flow states involve vortex densities pinned by the roughness of the substrate which can include left and right circulating vortices present simultaneously within the resonator. Densities are measured to be on the order of ${10}^5$/${\mathrm{cm}}^2$. The peak flow speed of the wave oscillations necessary to swirl the film are near the critical velocity for dc flow dissipation.