An optically trapped mixture of alkali-metal and metastable helium atoms

Ultracold collisions between alkali-metal and metastable triplet helium (He*) atoms provide the opportunity to study Feshbach resonances in the presence of a strong loss channel, namely Penning ionization, which strongly depends on the internal spin-states of the atoms. Recently we have realized the first optically trapped alkali-metal-metastable helium mixture. To prepare the ultracold $^{\mathrm{87}}$Rb$+^{\mathrm{4}}$He* mixture in a single beam optical dipole trap (ODT), we apply evaporative cooling in a strong quadrupole magnetic trap (QMT) for both species and subsequent transfer to the ODT via a hybrid trap [1,2]. We will present lifetime measurements of different spin-state mixtures, testing the application of the universal loss model [3] to this interesting multichannel collision system. [1] H. P. Mishra, A. S. Flores, W. Vassen, S. Knoop, Eur. Phys. J. D 69, 52 (2015) [2] A. S. Flores, H. P. Mishra, W. Vassen, S. Knoop, Appl. Phys. B 121, 391 (2015) [3] Z. Idziaszek and P. S. Julienne, Phys. Rev. Lett. 104, 113202 (2010)