Quantum Monte Carlo studies of superfluid Fermi gases

Journal Article · Fri Oct 01 04:00:00 EDT 2004 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.70.043602· OSTI ID:20646396

Chang, S Y; Pandharipande, V R; Carlson, J; Schmidt, K E ^[1]

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1. Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801 (United States)

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, ak{sub F}. We report results for the ground-state energy, the pairing gap {delta}, and the quasiparticle spectrum. In the weak-coupling regime, 1/ak{sub F}<-1, we obtain Bardeen-Cooper-Schrieffer (BCS) superfluid and the energy gap {delta} is much smaller than the Fermi gas energy E{sub FG}. When a>0, the interaction is strong enough to form bound molecules with energy E{sub mol}. For 1/ak{sub F} > or approx. 0.5, we find that weakly interacting composite bosons are formed in the superfluid gas with {delta} and gas energy per particle approaching E{sub 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/ak{sub F}<0.5, is discussed.

• OSTI ID: 20646396
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 70; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
BCS THEORY
BOSE-EINSTEIN CONDENSATION
BOSONS
COUPLING
ENERGY GAP
FERMI GAS
FERMIONS
GROUND STATES
MOLECULES
MONTE CARLO METHOD
S WAVES
SCATTERING LENGTHS
SUPERFLUIDITY
TWO-BODY PROBLEM
VECTORS