arXiv:1104.4430 · Physical Review Letters

Quantum Degenerate Mixtures of Alkali and Alkaline-Earth-Like Atoms

Hideaki Hara, Yosuke Takasu, Yoshifumi Yamaoka, John M. Doyle, Yoshiro Takahashi

Published May 19, 2011• 158 citations

Abstract

We realize simultaneous quantum degeneracy in mixtures consisting of the alkali and alkaline-earth-like atoms Li and Yb. This is accomplished within an optical trap by sympathetic cooling of the fermionic isotope $^{6}\mathrm{Li}$ with evaporatively cooled bosonic $^{174}\mathrm{Yb}$ and, separately, fermionic $^{173}\mathrm{Yb}$. Using cross-thermalization studies, we also measure the elastic $s$-wave scattering lengths of both Li-Yb combinations, $|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{174}\mathrm{Yb}}|=1.0\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}$ and $|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{173}\mathrm{Yb}}|=0.9\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}$. The equality of these lengths is found to be consistent with mass-scaling analysis. The quantum degenerate mixtures of Li and Yb, as realized here, can be the basis for creation of ultracold molecules with electron spin degrees of freedom, studies of novel Efimov trimers, and impurity probes of superfluid systems.

DOI: 10.1103/physrevlett.106.205304

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arXiv:1104.4430 · Physical Review Letters

Quantum Degenerate Mixtures of Alkali and Alkaline-Earth-Like Atoms

Hideaki Hara, Yosuke Takasu, Yoshifumi Yamaoka, John M. Doyle, Yoshiro Takahashi

Published May 19, 2011• 158 citations

arXiv HTML PDF

Abstract

^{6}\mathrm{Li}

with evaporatively cooled bosonic

^{174}\mathrm{Yb}

and, separately, fermionic

^{173}\mathrm{Yb}

. Using cross-thermalization studies, we also measure the elastic

s

-wave scattering lengths of both Li-Yb combinations,

|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{174}\mathrm{Yb}}|=1.0\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}

and

|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{173}\mathrm{Yb}}|=0.9\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}

. The equality of these lengths is found to be consistent with mass-scaling analysis. The quantum degenerate mixtures of Li and Yb, as realized here, can be the basis for creation of ultracold molecules with electron spin degrees of freedom, studies of novel Efimov trimers, and impurity probes of superfluid systems.

DOI: 10.1103/physrevlett.106.205304

Related papers

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Mar 9, 202126 citations

^{6}\mathrm{Li}

with evaporatively cooled bosonic

^{174}\mathrm{Yb}

and, separately, fermionic

^{173}\mathrm{Yb}

. Using cross-thermalization studies, we also measure the elastic

s

-wave scattering lengths of both Li-Yb combinations,

|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{174}\mathrm{Yb}}|=1.0\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}

and

|{a}_{^{6}\mathrm{Li}\ensuremath{-}^{173}\mathrm{Yb}}|=0.9\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{nm}

We have produced a quantum degenerate mixture of fermionic alkali-metal

{}^{6}

Li and bosonic spin-singlet

{}^{174}

Yb gases. This was achieved using sympathetic cooling of lithium atoms by evaporatively cooled ytterbium atoms in a far-off-resonant optical dipole trap. We observe the coexistence of Bose-condensed ($T/{T}_{\mathrm{c}}\ensuremath{\simeq}0.8$)

{}^{174}

Yb with $2.3\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms and Fermi degenerate ($T/{T}_{\mathrm{F}}\ensuremath{\simeq}0.3$)

{}^{6}

Li with $1.2\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms. Quasipure Bose-Einstein condensates of up to $3\ifmmode\times\else\texttimes\fi{}{10}^{4}$

{}^{174}

Yb atoms can be produced in single-species experiments. Our results mark a significant step toward studies of few- and many-body physics with mixtures of alkali-metal and alkaline-earth-metal-like atoms, and for the production of paramagnetic polar molecules in the quantum regime. Our methods also establish a convenient scheme for producing quantum degenerate ytterbium atoms in a 1064 nm optical dipole trap.

We report the realization of a degenerate mixture of

^{166}

Er and

^{7}

Li atoms in their energetically lowest spin states. The two species are sequentially laser-cooled and loaded into an optical dipole trap, then transported to a glass cell and simultaneously evaporated to degeneracy. Er serves as the coolant for Li, and we observe efficient sympathetic cooling facilitated by a large interspecies elastic scattering cross section. Three-body losses are found to be small, making this platform promising for the study of interacting mixtures with large mass imbalance.

An admixture of

{}^{87}

Rb and

{}^{171}

Yb atoms is prepared and cooled down to quantum degeneracy in a hybrid optical dipole trap independently tunable for both atomic species, which makes experimentalists ready to explore intriguing quantum phenomena such as the behavior of polarons on a lattice with alkali-metal--alkaline-earth-metal mixtures.

{}^{87}

Rb with either

{}^{88}

Sr or

{}^{84}

Sr, reaching more than $1\ifmmode\times\else\texttimes\fi{}{10}^{5}$ condensed atoms per element for the

{}^{84}

Sr-

{}^{87}

Rb mixture. These quantum gas mixtures constitute an important step towards the production of a quantum gas of polar, open-shell RbSr molecules.