Evaporative cooling of unitary Fermi gas mixtures in optical traps

Published

Journal Article

We measure the scaling laws for the number of atoms and the cloud size as a function of trap depth for evaporative cooling of a unitary Fermi gas in an optical trap. A unitary Fermi gas comprises a trapped mixture of atoms in two hyperfine states which is tuned to a collisional (Feshbach) resonance using a bias magnetic field. Near resonance, the zero energy s-wave scattering length diverges, and the s-wave scattering cross-section is limited by unitarity to be 4π/k2, where k is the relative wavevector of the colliding particles. In this case, the collision cross-section for evaporation scales inversely with the trap depth, enabling runaway evaporation under certain conditions. We demonstrate high evaporation efficiency, which is achieved by maintaining a high ratio ηof trap depth to thermal energy as the trap depth is lowered. We derive and demonstrate a trap lowering curve which maintains η constant for a unitary gas. This evaporation curve yields a quantum degenerate sample from a classical gas in a fraction of a second, with only a factor of three loss in atom number. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Full Text

Duke Authors

Cited Authors

  • Luo, L; Clancy, B; Joseph, J; Kinast, J; Turlapov, A; Thomas, JE

Published Date

  • September 27, 2006

Published In

Volume / Issue

  • 8 /

Electronic International Standard Serial Number (EISSN)

  • 1367-2630

International Standard Serial Number (ISSN)

  • 1367-2630

Digital Object Identifier (DOI)

  • 10.1088/1367-2630/8/9/213

Citation Source

  • Scopus