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

Yoji Ohashi, A. Griffin

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Abstract

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 [Formula Presented] 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 Nozières 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 [Formula Presented] 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 [Formula Presented] We also discuss the “phase diagram” above [Formula Presented] as a function of the tunable threshold energy [Formula Presented] We introduce a characteristic temperature [Formula Presented] describing the effective crossover in the normal phase from a Fermi gas of atoms to a gas of stable molecules.

Original languageEnglish
Number of pages1
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Volume67
Issue number3
DOIs
Publication statusPublished - 2003 Jan 1
Externally publishedYes

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transition temperature
Bose-Einstein condensates
gases
atoms
crossovers
composite materials
thresholds
bosons
energy
phase diagrams
traps
interactions
harmonics
profiles
approximation
molecules
temperature

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

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title = "Superfluid transition temperature in a trapped gas of Fermi atoms with a Feshbach resonance",
abstract = "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 [Formula Presented] 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 Nozi{\`e}res 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 [Formula Presented] 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 [Formula Presented] We also discuss the “phase diagram” above [Formula Presented] as a function of the tunable threshold energy [Formula Presented] We introduce a characteristic temperature [Formula Presented] describing the effective crossover in the normal phase from a Fermi gas of atoms to a gas of stable molecules.",
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