Quantum Monte Carlo Studies of Superfluid Fermi Gases

Abstract

We report results of quantum Monte Carlo calculations of the ground state of dilute Fermi gases with attractive short range two-body interactions. The strength of the interaction is varied to study different pairing regimes which are characterized by the product of the s-wave scattering length and the Fermi wave vector, $a{k}_F$. We report results for the ground state energy, the pairing gap $\Delta$ and the quasiparticle spectrum. In the weak coupling regime, $1/a{k}_F<-1$, we obtain BCS superfluid and the energy gap $\Delta$ is much smaller than the Fermi gas energy $E_{FG}$. When $a>0$, the interaction is strong enough to form bound molecules with energy $E_{mol}$. For $1/a{k}_F\gtrsim 0.5$ we find that weakly interacting composite bosons are formed in the superfluid gas with $\Delta$ and gas energy per particle approaching $|E_{mol}|/2$. In this region we seem to have Bose-Einstein condensation (BEC) of molecules. The behavior of the energy and the gap in the BCS to BEC transition region, $-0.5<1/a{k}_F<0.5$ is discussed.

11 figures, 3 tables

References in corpus (5)

• Observation of resonance condensation of fermionic atom pairs
• Observation of a Strongly-Interacting Degenerate Fermi Gas of Atoms
• Creation of ultracold molecules from a Fermi gas of atoms
• Crossover from a molecular Bose-Einstein condensate to a degenerate Fermi gas
• Superfluid Fermi Gases with Large Scattering Length

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