Observation of a Remanent Vortex-Line Density in Superfluid Helium

Abstract

Sensitive ion-trapping measurements show that superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ at rest contains a substantial number of quantized vortex lines, metastably pinned between the walls of the container. This remanent line density appears to be history independent, and is established upon going through the lambda point.