Bose-Einstein condensation of 88Sr through sympathetic cooling with 87Sr
Mickelson, P.G.; Martinez de Escobar, Y.N.; Yan, M.; DeSalvo, B.J.; Killian, T.C.
We report Bose-Einstein condensation of Sr88, which has a small, negative s-wave scattering length (a88=−2a0). We overcome the poor evaporative cooling characteristics of this isotope by sympathetic cooling with Sr87 atoms. Sr87 is effective in this role despite the fact that it is a fermion because of the large ground-state degeneracy arising from a nuclear spin of I=9/2, which reduces the impact of Pauli blocking of collisions. We observe a limited number of atoms in the condensate (Nmax≈104) that is consistent with the value of a88 and the optical dipole trap parameters.