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Sound Propagation in Degenerate <sup>133</sup>Cs-<sup>6</sup>Li Bose-Fermi Mixtures

ORAL

Abstract

We investigate sound propagation in Bose-Einstein condensates of 133Cs atoms immersed in degenerate Fermi gases of 6Li atoms. Deep in quantum degeneracy, fermionic excitations near the Fermi surface mediate interactions between bosons, modifying the sound speed in the condensates.

With a high-resolution microscope and a digital micromirror device, we create and image sound excitations in the BEC. The sound speed is measured at varying interspecies interaction strengths, utilizing a Li-Cs Feshbach resonance. At negative interspecies interactions, we observe heavy reduction of the sound speed while no effect is measured at positive interspecies interactions.Our measurements further reveal the nature of fermion-mediated interactions between bosons in the strong coupling regime.

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Presenters

  • Geyue Cai

    James Franck Institute, Enrico Fermi Institute, Department of Physics, University of Chicago

Authors

  • Geyue Cai

    James Franck Institute, Enrico Fermi Institute, Department of Physics, University of Chicago

  • Krutik Patel

    James Franck Institute, Enrico Fermi Institute, Department of Physics, University of Chicago

  • Chang Li

    James Franck Institute, Enrico Fermi Institute, Department of Physics, University of Chicago

  • Cheng Chin

    James Franck Institute, Enrico Fermi Institute, Department of Physics, University of Chicago, University of Chicago, Chicago, James Franck Institute, Enrico Fermi Institute, Department of Physics University of Chicago