Superfluid pairing gap in strong coupling

Phys Rev Lett. 2008 Apr 18;100(15):150403. doi: 10.1103/PhysRevLett.100.150403. Epub 2008 Apr 17.


The zero-temperature pairing gap is a fundamental property of interacting Fermions, providing a crucial test of many-body theories in strong coupling. We analyze recent cold-atom experiments on imbalanced Fermi systems using Quantum Monte Carlo results for the superfluid and normal phases. Through this analysis we extract, for the first time, the experimental zero-temperature pairing gap in the fully paired superfluid state at unitarity where the two-body scattering length is infinite. We find that the zero-temperature pairing gap is greater than 0.4 times the Fermi energy E(F), with a preferred value of (0.45+/-0.05) E(F). The ratio of the pairing gap to the Fermi Energy is larger here than in any other Fermi system measured to date.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.