Researchers at JILA, a joint institute of NIST and the University of Colorado Boulder, have discovered another parallel between ultracold atomic gases and high-temperature superconductors. The study, published in Nature Physics, suggests that similar behaviors in these very different systems may have a relatively simple shared explanation.
The JILA team, working with Italian theorists, found evidence of atom pairing in an ultracold gas of potassium atoms above the critical temperature where superfluidity disappears. This demonstrates the existence of a “pseudo-gap region” where the system retains some pairs of correlated fermions but not all characteristics of superfluidity.
The findings build on previous JILA research exploring the crossover behavior of atoms in a Fermi gas, which can act like both Bose Einstein condensates and separated electron pairs in a superconductor. The study was made possible by significant improvements in the signal strength of the atom photoemission spectroscopy technique since 2008.
The research suggests that having a pseudo-gap phase does not necessarily require complicated explanations, such as lattice effects, two-dimensionality, or exotic pairing mechanisms. The findings could help scientists better understand high-temperature superconductors, which have potential applications in more efficient electricity transmission across power grids.
Keywords: superconductors, ultracold atomic gases, superfluidity, fermions, photoemission spectroscopy
