extremely low temperature (below 0.01 K)
Technical term in physics for temperatures below 0.01 kelvin, colder than the more general 超低温 (ultra-low temperature).
See also: 超低温
In experiments at extremely low temperatures, materials exhibit quantum effects.
超低温 refers to ultra-low temperatures in general (often below about 1 K), while 超極低温 specifically means temperatures below 0.01 K.
Compound of 超 (super, ultra), 極 (extreme), and 低温 (low temperature). The term is a technical coinage in physics.