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Phase Diagrams for a Fermi Gas with a Feshbach Resonance

Tetsuro Nikuni, Nicolai Gayle Nygaard, JAMES E. JUN. WILLIAMS +1 more

Bulletin of the American Physical SocietyMar 23, 20050 citations

Phase Diagram of a Polarized Fermi Gas Across a Feshbach Resonance

Wenhui Li, Yean-an Liao, Guthrie B. Partridge +1 more

Bulletin of the American Physical SocietyJun 7, 20070 citations

Phase Diagram of a Polarized Fermi Gas Across a Feshbach

Wenhui Li, Yean-an Liao, Guthrie B. Partridge +1 more

Bulletin of the American Physical SocietyOct 19, 20070 citations

Collisionless conversion of a degenerate Fermi gas into molecules in a Feshbach resonance

Juha Javanainen, Matt Mackie

APSMay 1, 20040 citations

Adiabatic Phase Diagram of an Ultracold Atomic Fermi Gas with a Feshbach Resonance

Shohei Watabe, Tetsuro Nikuni, Nicolai Gayle Nygaard +2 more

We determine the adiabatic phase diagram of a resonantly-coupled system of Fermi atoms and Bose molecules confined in the harmonic trap by using the local density approximation. The adiabatic phase diagram shows the fermionic condensate fraction composed of condensed molecules and Cooper pair atoms. The key idea of our work is conservation of entropy through the adiabatic process, extending the study of Williams et al. [Williams et al., New J. Phys. 6, 123 (2004)] for an ideal gas mixture to include the resonant interaction in a mean-field theory. We also calculate the molecular conversion efficiency as a function of initial temperature. Our work helps to understand recent experiments on the BCS-BEC crossover, in terms of the initial temperature measured before a sweep of the magnetic field.We determine the adiabatic phase diagram of a resonantly-coupled system of Fermi atoms and Bose molecules confined in the harmonic trap by using the local density approximation. The adiabatic phase diagram shows the fermionic condensate fraction composed of condensed molecules and Cooper pair atoms. The key idea of our work is conservation of entropy through the adiabatic process, extending the study of Williams et al. [Williams et al., New J. Phys. 6, 123 (2004)] for an ideal gas mixture to include the resonant interaction in a mean-field theory. We also calculate the molecular conversion efficiency as a function of initial temperature. Our work helps to understand recent experiments on the BCS-BEC crossover, in terms of the initial temperature measured before a sweep of the magnetic field.

arXiv:cond-mat/0610079Journal of the Physical Society of JapanMay 25, 20075 citations

Conversion of a Degenerate Fermi Gas of 6Li Atoms to a Molecular BEC

Kevin E. Strecker

Atomic Feshbach resonances have recently been used to produce a strongly interacting Fermi gas, where the BCS/BEC crossover can be explored. We have used both narrow and broad Feshbach resonances to convert a quantum degenerate Fermi gas of 6Li atoms into an ultracold gas of Li2 molecules. For the narrow resonances, the molecules are formed by coherent adiabatic passage through the resonance. We find that 50% of the atoms are converted to molecules. Furthermore, the lifetime of these molecules was measured to be surprisingly long, 1 s. We will discuss these measurements in the context of the present theoretical understanding. Molecules can also be formed using static fields near the broad Feshbach resonance. The lifetime of these molecules is again long, and sufficient to enable their evaporation to a Bose‐Einstein condensate. Phase contrast images of the molecular condensate are presented. The BCS/BEC crossover may be explored by starting with a pure molecular condensate on the low‐field side of the Feshbach resonance, and adiabatically changing the field to any final value around resonance. We combine this ability with optical spectroscopy on a bound‐bound molecular transition to probe the nature of the many‐body wavefunction in the crossover regime.Atomic Feshbach resonances have recently been used to produce a strongly interacting Fermi gas, where the BCS/BEC crossover can be explored. We have used both narrow and broad Feshbach resonances to convert a quantum degenerate Fermi gas of 6Li atoms into an ultracold gas of Li2 molecules. For the narrow resonances, the molecules are formed by coherent adiabatic passage through the resonance. We find that 50% of the atoms are converted to molecules. Furthermore, the lifetime of these molecules was measured to be surprisingly long, 1 s. We will discuss these measurements in the context of the present theoretical understanding. Molecules can also be formed using static fields near the broad Feshbach resonance. The lifetime of these molecules is again long, and sufficient to enable their evaporation to a Bose‐Einstein condensate. Phase contrast images of the molecular condensate are presented. The BCS/BEC crossover may be explored by starting with a pure molecular condensate on the low‐field side of the Feshbach resonance, and adiabatically changing the field to any final value around resonance. We combine this ability with optical spectroscopy on a bound‐bound molecular transition to probe the nature of the many‐body wavefunction in the crossover regime.

AIP conference proceedingsJan 1, 20050 citations

Adiabatic Phase Diagram of a Degenerate Fermi Gas with a Feshbach Resonance

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Adiabatic Phase Diagram of a Degenerate Fermi Gas with a Feshbach Resonance

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