The matter family has added a new member. Most everyone knows the four most common forms of matter ? solid, liquid, gas, and plasma. A fifth, the Bose-Einstein condensate (BEC) was first observed in 1995. Now a sixth has been added to the mix, the fermionic condensate. Bose-Einstein condensates are formed when the atoms in a mixture all occupy the same quantum state, but there is one problem with BECs. BECs are are formed from bosons, particles like photons and alpha particles, which have zero or integral spin. Fermions, on the other hand, are the basic building blocks of matter, have fractional spins, and because of the Pauli exclusion principle, cannot occupy the same quantum state.
Ever since the formation of the first BEC, scientists have been racing to form condensates with different forms of matter. This race was started because it was believed a fermionic condensate was a bridge between superconductivity and BECs. Researchers at JILA labs in Boulder, Colorado and in Austria created a molecular BEC from lithium late last year, but the trick to creating a fermionic condensate is to keep the atoms from forming molecules. Since quantum spins are additive, if you could coax a pair of fermions atoms to form a "Cooper pair", they would act like a boson. If they could allow these atoms condense without forming molecular bonds, this fermionic condensate could be used to study the basics of superconductivity and superfluidity in a homogeneous material.
Using an optical trap at temperatures slightly above absolute zero, the team at JILA used magnetic fields strengths that allowed potassium-40 atoms to form Cooper pairs more readily than molecular bonds. Paradoxically, to confirm they formed a fermionic condensate, they had to convert the paired atoms into molecules. They changed the magnetic field to a strength that favored molecular bonding and released the optical trap so a molecular BEC would not form. Yea...so what does all this mean, and why should we be interested in it?
"The strength of pairing in our fermionic condensate would correspond to a room temperature superconductor when adjusted for mass and density," said Jin at a press conference today. "This makes me optimistic that the fundamental physics we learn through fermionic condensates will eventually help others design more practical superconducting materials."
I was going to add something more, but that quote summed it up quite nicely.