Chromium dipolar Fermi sea

Abstract

We report on the production of a degenerate Fermi gas of $^{53}\mathrm{Cr}$ atoms, polarized in the state $F=9/2, {m}_{F}=\ensuremath{-}9/2$, by sympathetic cooling with bosonic $S=3,\phantom{\rule{0.16em}{0ex}}{m}_{S}=\ensuremath{-}3 ^{52}\mathrm{Cr}$ atoms. We load in an optical dipole trap $3\ifmmode\times\else\texttimes\fi{}{10}^{4}^{53}\mathrm{Cr}$ atoms with ${10}^{6} ^{52}\mathrm{Cr}$ atoms. Despite the initial small number of fermionic atoms, we reach a final temperature of $T\ensuremath{\simeq}0.6\ifmmode\times\else\texttimes\fi{}{T}_{f}$ (Fermi temperature), with up to ${10}^{3} ^{53}\mathrm{Cr}$ atoms. This surprisingly efficient evaporation stems from an interisotope scattering length $|{a}_{BF}|=80(\ifmmode\pm\else\textpm\fi{}10){a}_{B}$ (Bohr radius) which is small enough to reduce evaporative losses of the fermionic isotope, but large enough to assure thermalization.