Liquid helium-4 can be cooled to about using evaporative cooling in a 1-K pot. Similar cooling of helium-3, which has a lower boiling point, can achieve about in a helium-3 refrigerator. Equal mixtures of liquid and below separate into two immiscible phases due to their dissimilarity (they follow different quantum statistics: helium-4 atoms are bosons while helium-3 atoms are fermions). Dilution refrigerators use this immiscibility to achieve temperatures of a few millikelvins.
Liquid helium-4 can b.e cooled to about using evaporative cooling in a 1-K pot. Similar cooling of helium-3, which has a lower boiling point, can achieve about in a helium-3 refrigerator. Equal mixtures of liquid and below separate into two immiscible phases due to their dissimilarity (they follow different quantum statistics: helium-4 atoms are bosons while helium-3 atoms are fermions). Dilution refrigerators use this immiscibility to achieve temperatures of a few millikelvins