Helium is unique among the elements in that it does not freeze at low temperatures and pressures, remaining a liquid all the way down to absolute zero at standard pressure. It also has the lowest boiling point, 4.22 K[1], and is the only element to has a superfluid phase transition (2.17 K). While a solid phase does exist, it requires extreme pressure, around 25 atmospheres. A phase diagram for...

A change in the shape of a charged surface of liquid hydrogen and helium — the formation of a solitary wave ~a positively charged hump for hydrogen and a negatively charged dimple for helium! – is observed in an electric field exceeding a critical value under conditions of total compensation of the applied field by the surface charge. © 1997 American Institute of Physics. @S0021-3640~97!01107-9#

The phenomenon of Non-Classical Rotational Inertia, in which a body does not rotate with its rotating container, has been recently observed in solid Helium-4. This property is shared by superfluid liquid helium. The recent findings might be evidence of superflow in solids. Superfluidity or flow sans dissipation is commonly associated with liquids. Counter-intuitive as it may seem, quantum mecha...

We address the problem of making quantitative measurements of local flow velocities in turbulent liquid helium, using tracer particles. We survey and evaluate presently available particles and previous work to establish the need to develop new particles for the purpose. We present the first practical solution for visualizing fluid motions using a suspension of solid hydrogen particles with diam...

The term quantum turbulence denotes the turbulent motion of quantum fluids, systems such as superfluid helium and atomic Bose-Einstein condensates, which are characterized by quantized vorticity, superfluidity, and, at finite temperatures, two-fluid behavior. This article introduces their basic properties, describes types and regimes of turbulence that have been observed, and highlights similar...

We describe recent progress in developing a superfluid helium analog of the superconducting dc-SQUID. The devices tested thus far are sensitive detectors of rotation as well as useful probes for studies of superfluidity. The key ingredients of the superfluid helium quantum interference device (SHeQUID) involve commercially available technology and modest cryogenic facilities. The superfluid sta...