Cold gas experiment bodes well for high temp superconductors

Cold gas experiment bodes well for high temp superconductors
HANCOCK, N.H. — A superconducting state midway between the condensed electron gas in a superconductor and the near absolute zero atomic gas of a Bose-Einstein condensate has been discovered at the Joint Institute for Laboratory Astrophysics (JILA) (Boulder, Colo.).

The new state of matter, discovered in a gas of potassium atoms that were cooled to near absolute zero temperatures, could shed light on high critical temperature superconductors, said lead researcher Deborah Jin.

Previously, Jin and her colleagues at JILA along with workers at the University of Colorado, Boulder had shown that potassium atoms in a fermionic state could link up to form boson-like aggregates that would then condense into a state known as a "Bose-Einstein condensate".

Building on that work, the researchers reported that the degree of correlation between the particles can be reduced, leading to a true fermionic gas, which physicists had assumed could not exist. Electrons in both low temperature and high-temperature superconductors are likewise fermionic gases.

"We now have a knob we can turn to study fermionic gases. Nobody knows how you can do this in a real superconductor, but just the fact that you can demonstrate this type of physics in this interesting regime says that it is possible," said Jin.

The "knob" is the ability to adjust the force of attraction between the atoms from strongly attracting (creating the Bose-Einstein state) and weakly repulsive, more like the interactions between electrons. The discovery has generated excitement in the physics community since the new state of matter appears to lie somewhere between Bose-Einstein condensates and the fermionic condensates observed in superconductors.