Density matrices of superfluid helium-4. II

I. O. Vakarchuk

Rabi Tsai-Hung Wang

Haruo Kojima

Abstract : Fourth sound techniques were extensively developed into a powerful tool for investigating persistent current states in rotating superfluid helium contained in a superleak. Unique features of these techniques are: (1) persistent superfluid component velocity is directly determined by the Doppler-shifted splitting of a fourth sound resonant mode in an annular cavity; (2) the superfluid component density is determined simultaneously and independently by measuring the velocity of fourth sound; (3) persistent current states are observed from a rotating frame. The fourth sound techniques allows observations of persistent current states which are otherwise inaccessible in a stationary measurement. As a consequence the authors show that every phenomenon observed in rotating locked superfluid helium (Bose superfluid) has an analogous counterpart in an irreversible type-II superconductor (Fermi superfluid). (Author)

Garry Eugene Noe

Pierre C. Hohenberg, Paul C. Martin

Luca Galantucci, Michele Sciacca, Carlo F. Barenghi

We perform fully coupled two-dimensional numerical simulations of plane channel helium II counterflows with vortex-line density typical of experiments. The main features of our approach are the inclusion of the back reaction of the superfluid vortices on the normal fluid and the presence of solid boundaries. Despite the reduced dimensionality, our model is realistic enough to reproduce vortex density distributions across the channel recently calculated in three dimensions. We focus on the coarse-grained superfluid and normal fluid velocity profiles, recovering the normal fluid profile recently observed employing a technique based on laser-induced fluorescence of metastable helium molecules.