If you think about superconductivity, where electrical resistance is zero, you need pairs of electrons – known as Cooper pairs – to form and condense.

"However, in the case of a four-fermion condensate that we report, the time reversal puts it in a different state," says Babaev.

That's fermionic quadrupling and a new state of matter.

The state of superconductivity is used everywhere, from quantum computers to magnetic resonance imaging (MRI) scanners, but it remains to be seen what's in store for the new state of matter made possible by fermionic quadrupling.