We derive the atom-molecule theory for an atomic gas near a broad Feshbach resonance, where the energy dependence of the atom-molecule coupling becomes crucial for understanding experimental results. We show how our many-body theory incorporates the two-atom physics exactly. In particular, we calculate the magnetic moment of a two-component gas of $^{6}\mathrm{Li}$ atoms for a wide range of magnetic fields near the broad Feshbach resonance at about $834\phantom{\rule{0.3em}{0ex}}\mathrm{G}$ . We find excellent agreement with the experiment of Jochim et al. [Phys. Rev. Lett. 91, 240402 (2003)].We derive the atom-molecule theory for an atomic gas near a broad Feshbach resonance, where the energy dependence of the atom-molecule coupling becomes crucial for understanding experimental results. We show how our many-body theory incorporates the two-atom physics exactly. In particular, we calculate the magnetic moment of a two-component gas of $^{6}\mathrm{Li}$ atoms for a wide range of magnetic fields near the broad Feshbach resonance at about $834\phantom{\rule{0.3em}{0ex}}\mathrm{G}$. We find excellent agreement with the experiment of Jochim et al. [Phys. Rev. Lett. 91, 240402 (2003)].

arXiv:cond-mat/0409621Physical Review AJun 27, 200527 citations

Molecule-molecule hyperfine Feshbach resonances

Alisdair O. G. Wallis, Roman V. Krems

Bulletin of the American Physical SocietyJun 7, 20120 citations

Self-consistent theory of atomic Fermi gases with a Feshbach resonance at the superfluid transition

Xia-Ji Liu, Hui Hu

A self-consistent theory is derived to describe the BCS--Bose-Einstein-condensate crossover for a strongly interacting Fermi gas with a Feshbach resonance. In the theory the fluctuation of the dressed molecules, consisting of both preformed Cooper pairs and ``bare'' Feshbach molecules, has been included within a self-consistent $T$ -matrix approximation, beyond the Nozi\`eres and Schmitt-Rink strategy considered by Ohashi and Griffin. The resulting self-consistent equations are solved numerically to investigate the normal-state properties of the crossover at various resonance widths. It is found that the superfluid transition temperature ${T}_{c}$ increases monotonically at all widths as the effective interaction between atoms becomes more attractive. Furthermore, a residue factor ${Z}_{m}$ of the molecule's Green function and a complex effective mass have been determined to characterize the fraction and lifetime of Feshbach molecules at ${T}_{c}$ . Our many-body calculations of ${Z}_{m}$ agree qualitatively well with recent measurments of the gas of $^{6}\mathrm{Li}$ atoms near the broad resonance at $834\phantom{\rule{0.3em}{0ex}}\mathrm{G}$ . The crossover from narrow to broad resonances has also been studied.A self-consistent theory is derived to describe the BCS--Bose-Einstein-condensate crossover for a strongly interacting Fermi gas with a Feshbach resonance. In the theory the fluctuation of the dressed molecules, consisting of both preformed Cooper pairs and ``bare'' Feshbach molecules, has been included within a self-consistent $T$-matrix approximation, beyond the Nozi\`eres and Schmitt-Rink strategy considered by Ohashi and Griffin. The resulting self-consistent equations are solved numerically to investigate the normal-state properties of the crossover at various resonance widths. It is found that the superfluid transition temperature ${T}_{c}$ increases monotonically at all widths as the effective interaction between atoms becomes more attractive. Furthermore, a residue factor ${Z}_{m}$ of the molecule's Green function and a complex effective mass have been determined to characterize the fraction and lifetime of Feshbach molecules at ${T}_{c}$. Our many-body calculations of ${Z}_{m}$ agree qualitatively well with recent measurments of the gas of $^{6}\mathrm{Li}$ atoms near the broad resonance at $834\phantom{\rule{0.3em}{0ex}}\mathrm{G}$. The crossover from narrow to broad resonances has also been studied.

arXiv:cond-mat/0505572Physical Review ADec 14, 200559 citations

Decay of Feshbach Resonances in Diatomic Molecules

Hélène Lefebvre-Brion, Annick Giusti-Suzor

Springer eBooksJan 1, 19830 citations

Bogoliubov theory of Feshbach molecules in the BEC-BCS crossover

M. W. J. Romans, Henk T. C. Stoof

We present the Bogoliubov theory for the Bose-Einstein condensation of Feshbach molecules in a balanced Fermi mixture. Because the Bogoliubov theory includes (Gaussian) fluctuations, we can in this manner accurately incorporate both the two-body and many-body aspects of the BEC-BCS crossover that occurs near a Feshbach resonance. We apply the theory in particular to the very broad Feshbach resonance in atomic $^{6}\mathrm{Li}$ at a magnetic field of ${B}_{0}=834\phantom{\rule{0.3em}{0ex}}\mathrm{G}$ and find good agreement with experiments in that case. The BEC-BCS crossover for more narrow Feshbach resonances is also discussed.We present the Bogoliubov theory for the Bose-Einstein condensation of Feshbach molecules in a balanced Fermi mixture. Because the Bogoliubov theory includes (Gaussian) fluctuations, we can in this manner accurately incorporate both the two-body and many-body aspects of the BEC-BCS crossover that occurs near a Feshbach resonance. We apply the theory in particular to the very broad Feshbach resonance in atomic $^{6}\mathrm{Li}$ at a magnetic field of ${B}_{0}=834\phantom{\rule{0.3em}{0ex}}\mathrm{G}$ and find good agreement with experiments in that case. The BEC-BCS crossover for more narrow Feshbach resonances is also discussed.

arXiv:cond-mat/0607045Physical Review ANov 17, 200614 citations

^{6}\mathrm{Li}

atoms for a wide range of magnetic fields near the broad Feshbach resonance at about

834\phantom{\rule{0.3em}{0ex}}\mathrm{G}

. We find excellent agreement with the experiment of Jochim et al. [Phys. Rev. Lett. 91, 240402 (2003)].

T

-matrix approximation, beyond the Nozi\`eres and Schmitt-Rink strategy considered by Ohashi and Griffin. The resulting self-consistent equations are solved numerically to investigate the normal-state properties of the crossover at various resonance widths. It is found that the superfluid transition temperature

{T}_{c}

increases monotonically at all widths as the effective interaction between atoms becomes more attractive. Furthermore, a residue factor

{Z}_{m}

of the molecule's Green function and a complex effective mass have been determined to characterize the fraction and lifetime of Feshbach molecules at

{T}_{c}

. Our many-body calculations of

{Z}_{m}

agree qualitatively well with recent measurments of the gas of

^{6}\mathrm{Li}

atoms near the broad resonance at

834\phantom{\rule{0.3em}{0ex}}\mathrm{G}

. The crossover from narrow to broad resonances has also been studied.

^{6}\mathrm{Li}

at a magnetic field of

{B}_{0}=834\phantom{\rule{0.3em}{0ex}}\mathrm{G}

and find good agreement with experiments in that case. The BEC-BCS crossover for more narrow Feshbach resonances is also discussed.