What is superfluidity in quantum mechanics?

Superfluidity is a non-classical state of matter characterized by zero viscosity, allowing a fluid to flow without any loss of kinetic energy. It occurs when specific substances, such as isotopes of helium, are cooled to cryogenic temperatures. This macroscopic quantum phenomenon is studied through quantum statistical mechanics and can produce striking behaviors, such as fluids flowing spontaneously up and over the rims of their containers.

What we know

• Superfluidity is the characteristic property of a fluid with zero viscosity that enables it to flow without losing kinetic energy. [2]
• The phenomenon occurs in two isotopes of helium, helium-3 and helium-4, when they are cooled to cryogenic temperatures. [2]
• Quantum statistical mechanics applies statistical methods to quantum systems, providing a theoretical explanation for phenomena like superfluidity. [4]
• When liquid helium is cooled near absolute zero in an open container, it can spontaneously flow up and over the rim. [5]

Still open

• The precise relationship between superfluidity and Bose-Einstein condensation remains complex, as neither phenomenon is directly caused by the other and their respective fractions can vary independently.

Where to go next

• compared withHow does Bose-Einstein condensation relate to quantum states?
• whoWhat role did Lev Landau play in developing quantum theories?
• how it workedHow does quantum statistical mechanics explain microscopic particle behavior?
• a case in pointWhat happens to liquid helium near absolute zero?
• the bigger pictureHow do macroscopic quantum phenomena manifest in physics?
• an unexpected connectionHow does superfluidity connect to theories of quantum gravity?Superfluidity is theorized to exist as an exotic state of matter in high-energy physics, astrophysics, and quantum gravity models.

Sources

• [1]superfluidity (Wikidata Q106667) · CC0 1.0
• [2]Superfluidity · CC BY-SA 4.0
• [3]Quantum gravity · CC BY-SA 4.0
• [4]Quantum statistical mechanics · CC BY-SA 4.0
• [5]Introduction to quantum mechanics · CC BY-SA 4.0