In quantum liquids, large differences are observed owing to differences in quantum statistics. The physical properties of liquid <sup>3</sup>He (Fermion) and <sup>4</sup>He (Boson) are considerably different at low temperatures. After the discovery of superconductivity in electron (i.e., Fermion) systems, a similar pairing ordered state was expected for <sup>3</sup>He. Remarkably, the observed ordered state of <sup>3</sup>He was more surprising than expected, multiple superfluid phases in the <em>T-P</em> phase diagram. The origin of the multiple phases was attributed to ferromagnetic interactions in the <em>p</em>-wave symmetry state.
The phase diagram of ultra quantum liquids
