Vladyslav Ivanov

Quantum Degenerate Mixture of Ytterbium and Lithium Atoms

We have produced a quantum degenerate mixture of fermionic alkali-metal {sup 6}Li and bosonic spin-singlet {sup 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{sub c}{approx_equal}0.8) {sup 174}Yb with 2.3x10{sup 4} atoms and Fermi degenerate (T/T{sub F}{approx_equal}0.3) {sup 6}Li with 1.2x10{sup 4} atoms. Quasipure Bose-Einstein condensates of up to 3x10{sup 4} {sup 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.

Sympathetic cooling in an optically trapped mixture of alkali and spin-singlet atoms.

We report on the realization of a stable mixture of ultracold lithium and ytterbium atoms confined in a far-off-resonance optical dipole trap. We observe sympathetic cooling of 6Li by 174Yb and extract the s-wave scattering length magnitude |a(6Li-174Yb)|=(13±3)a0 from the rate of interspecies thermalization. Using forced evaporative cooling of 174Yb, we achieve reduction of the 6Li temperature to below the Fermi temperature, purely through interspecies sympathetic cooling.