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Achieving a BCS transition in an atomic Fermi gas
L D Carr1, G V Shlyapnikov, Y Castin
1Laboratoire Kastler Brossel, Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris, France.
Physical Review Letters
|June 1, 2004
Summary
Researchers demonstrate transforming a Bose-Einstein condensate of molecules into a degenerate Fermi gas by tuning atomic interactions. This method achieves a low temperature-to-Fermi temperature ratio, enabling exploration of the BCS transition in cold atomic gases.
Area of Science:
- Atomic, Molecular, and Optical (AMO) Physics
- Condensed Matter Physics
- Quantum Gases
Background:
- Cold atomic gases offer controllable quantum systems.
- Interactions in fermionic gases can lead to molecular Bose-Einstein condensates or Bardeen-Cooper-Schrieffer (BCS) pairing.
- Tuning interatomic interactions is key to exploring quantum phases.
Purpose of the Study:
- To investigate the adiabatic transformation of a molecular Bose-Einstein condensate into a degenerate Fermi gas.
- To explore the critical conditions for the Bardeen-Cooper-Schrieffer (BCS) transition in an interacting Fermi gas.
- To achieve highly degenerate Fermi gases from molecular condensates.
Main Methods:
- Utilizing a gas of cold fermionic atoms with two spin components.
- Adiabatically tuning the s-wave scattering length (a) from positive to negative values.
- Evaporative cooling to form Bose-Einstein condensates and exploring BCS pairing.
Main Results:
- Demonstrated the transformation of a molecular Bose-Einstein condensate into a highly degenerate atomic Fermi gas.
- Achieved a low ratio of temperature to Fermi temperature (T/T(F)) of approximately 10(-2).
- Determined the critical final value of k(F)/a/ for the BCS transition to be approximately one-half.
Conclusions:
- Adiabatic tuning of scattering length provides a pathway to create highly degenerate Fermi gases.
- The study establishes a critical interaction parameter for the BCS transition in this system.
- This work facilitates the study of quantum phenomena in strongly interacting Fermi gases.
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