arXiv:0901.3148 · Physical Review Letters

Heavy-Light Fermion Mixtures at Unitarity

Alexandros Gezerlis, Stefano Gandolfi, Kevin E. Schmidt, Joseph Carlson

Published Aug 5, 2009• 66 citations

Abstract

We investigate fermion pairing in the unitary regime for a mass ratio corresponding to a ;{6}Li-;{40}K mixture using quantum Monte Carlo methods. The ground-state energy and the average light- and heavy-particle excitation spectrum for the unpolarized superfluid state are nearly independent of the mass ratio. In the majority light system, the polarized superfluid is close to the energy of a phase separated mixture of nearly fully polarized normal and unpolarized superfluid. For a majority of heavy particles, we find an energy minimum for a normal state with a ratio of approximately 3ratio1 heavy to light particles. A slight increase in attraction to k_{F}a approximately 2.5 yields a ground state energy of nearly zero for this ratio. A cold unpolarized system in a harmonic trap at unitarity should phase separate into three regions, with a shell of unpolarized superfluid in the middle.

DOI: 10.1103/physrevlett.103.060403

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