A high phase-space density mixture of ${}^{87}$Rb and ${}^{133}$Cs: towards ultracold heteronuclear molecules

Abstract

We report the production of a high phase-space density mixture of ${}^{87}$Rb and ${}^{133}$Cs atoms in a levitated crossed optical dipole trap as the first step towards the creation of ultracold RbCs molecules via magneto-association. We present a simple and robust experimental setup designed for the sympathetic cooling of ${}^{133}$Cs via interspecies elastic collisions with ${}^{87}$Rb. Working with the $|F=1,m_F=+1>$ and the $|3,+3>$ states of ${}^{87}$Rb and ${}^{133}$Cs respectively, we measure a high interspecies three-body inelastic collision rate $\sim 10^{-25}-10^{-26}{\mathrm{cm}}^6{\mathrm{s}}^{-1}$ which hinders the sympathetic cooling. Nevertheless by careful tailoring of the evaporation we can produce phase-space densities near quantum degeneracy for both species simultaneously. In addition we report the observation of an interspecies Feshbach resonance at 181.7(5) G and demonstrate the creation of Cs${}_2$ molecules via magneto-association on the 4g(4) resonance at 19.8 G. These results represent important steps towards the creation of ultracold RbCs molecules in our apparatus.

7 pages, 6 figures

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Cited by in corpus (4)

• Dual-Species Bose-Einstein Condensate of ${}^{87}$Rb and ${}^{133}$Cs
• Equilibrium solutions of immiscible two-species Bose-Einstein condensates in perturbed harmonic traps
• Feshbach resonances in ultracold 85Rb
• Feshbach spectroscopy of an ultracold mixture of ${}^{85}$Rb and ${}^{133}$Cs