Superfluid helium-4 (helium II or He-II) is the superfluid form of helium-4, an isotope of the element helium. A superfluid is a state of matter in which matter behaves like a fluid with zero viscosity.

When liquid helium-4 is cooled to below 2.17 K (−270.98 °C), it becomes a superfluid, with properties very different from those of an ordinary liquid. For example, if superfluid helium-4 is placed in an open vessel, a thin Rollin film will climb the …

Historical overview on the research on superfluid Helium 4. In 1908, Kammerlingh Onnes succeeded for the first time in liquefying helium in Leiden. In 1938. Allen and Misener, and Kapitza independently discovered that it exhibited a superfluid behavior.

Superfluidity is the characteristic property of a fluid with zero viscosity which therefore flows without any loss of kinetic energy. When stirred, a superfluid forms vortices that continue to rotate indefinitely. Superfluidity occurs in two isotopes of helium (helium-3 and helium-4) when they are liquefied by cooling to cryogenic temperatures.

2024年2月14日 · The strange properties of superfluid helium-4 (also known as liquid helium II) arise because of the quantum rules governing the symmetry of the wave functions of helium atoms. Electrons, which are fermions, cannot occupy the same quantum state, but the same is not true for helium-4 atoms.

In helium-4 superfluid experiments, liquid helium is often cooled via evaporation. To accelerate the cooling process, helium vapors are pumped out from their container. The evaporation takes place not only on the surface but also within the liquid. Helium bubbles rise like boiling water.

phenomenon of superfluidity in liquid helium-4. The experimentally observed properties of superfluid 4He are described, and outline explanations are given in terms of the existence of a Bose condensate and a special form of excitation spectrum. The quantization of superfluid circulation is described, and the role played by free

2023年11月2日 · An experiment has finally revealed how it might feel to touch a quantum superfluid. Physicists dunked a special, finger-sized probe into an isotope of helium cooled to just a smidge over absolute zero, and recorded the physical properties therein.

In these brief notes we shall focus our attention on superfluidity in liquid 4He, emphasizing the underlying physical principles, including those associated with macroscopic quantum phenomena, and we shall place some emphasis on aspects that relate to practical applications.

2018年1月15日 · In 1938, Allen and Misener 1 and Kapitza 2 showed that liquid helium-4 becomes a superfluid — a fluid with zero viscosity — at very low temperatures.