Superfluid transition temperature in a trapped gas of Fermi atoms with a Feshbach resonance

Journal Article · Sat Mar 01 04:00:00 EST 2003 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.67.033603· OSTI ID:20633868

Ohashi, Y ^[1]; Griffin, A ^[1]

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1. Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7 (Canada)

We investigate strong-coupling effects on the superfluid phase transition in a gas of Fermi atoms with a Feshbach resonance. The Feshbach resonance describes a composite quasiboson that can give rise to an additional pairing interaction between the Fermi atoms. This attractive interaction becomes stronger as the threshold energy 2{nu} of the Feshbach resonance two-particle bound state is lowered. In a recent paper, we showed that in the uniform Fermi gas, this tunable pairing interaction naturally leads to a crossover from a BCS state to a Bose-Einstein condensate (BEC) of the Nozieres and Schmitt-Rink kind, in which the BCS-type superfluid phase transition continuously changes into the BEC type as the threshold energy is decreased. In this paper, we extend our previous work by including the effect of a harmonic trap potential, treated within the local-density approximation. We also give results for both weak and strong coupling to the Feshbach resonance. We show that the BCS-BEC crossover phenomenon strongly modifies the shape of the atomic density profile at the superfluid phase-transition temperature T{sub c}, reflecting the change of the dominant particles going from Fermi atoms to composite bosons. In the BEC regime, these composite bosons are shown to first appear well above T{sub c}. We also discuss the 'phase diagram' above T{sub c} as a function of the tunable threshold energy 2{nu}. We introduce a characteristic temperature T*(2{nu}) describing the effective crossover in the normal phase from a Fermi gas of atoms to a gas of stable molecules.

• OSTI ID: 20633868
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 3 Vol. 67; 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
ATOMS
BINDING ENERGY
BOSE-EINSTEIN CONDENSATION
BOSONS
BOUND STATE
DENSITY
FERMI GAS
FLUCTUATIONS
MOLECULES
PAIRING INTERACTIONS
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
POTENTIALS
RESONANCE
SUPERFLUIDITY
THRESHOLD ENERGY
TRANSITION TEMPERATURE
TRAPPING
TRAPS