Observation of state-to-state hyperfine-changing collisions in a Bose-Fermi mixture of Li6 and K41 atoms

Abstract

Hyperfine-changing collisions are of fundamental interest for the studying of ultracold heteronuclear mixtures. Here, we report the state-to-state study of the hyperfine-changing-collision dynamics in a Bose-Fermi mixture of 6 Li and 41 K atoms. The collision products are directly observed and the spin-changing dynamics is measured. Based on a two-body collision model, the experimental results are simultaneously fitted from which the spin-changing rate coefficient of 1.9(2) × 10 −12 cm 3 · s −1 is gained, being consistent with the multi-channel quantum defect theory calculation. We further show that the contact parameter of 6 Li-41 K mixture can be extracted from the measured spin-changing dynamics. The obtained results are consistent with the first order perturbation theory in the weakly-interacting limit. Our system offers great promise for studying spin-changing interactions in heteronuclear mixtures. arXiv:2001.11652v1 [cond-mat.quant-gas] 31 Jan 2020

Engineering long-range interactions between ultracold atoms with light

“…In the present case, such a two-photon excited channel is irrelevant. Therefore the idea would be to look for hyperfine-changing collisions (hcc) [66][67][68][69][70] leading to trap loss, especially in shallow traps. This phenomena is taken into account in an effective way in our model through the P S parameter.…”

“…This phenomena is taken into account in an effective way in our model through the P S parameter. Such collisions have long been considered as a serious issue to achieve quantum degeneracy, and now as an additional possibility for controlling the appearance of new quantum phases in quantum gases [70]. Therefore, the OS would manifest by a reduction of losses from the trap, when one of the atoms is prepared in an excited level of the ground state hyperfine manifold.…”

“…Therefore, the OS would manifest by a reduction of losses from the trap, when one of the atoms is prepared in an excited level of the ground state hyperfine manifold. In the recent investigation of a 6 Li-41 K ultracold mixture [70], the final state of the hcc products is measured, and OS would then be detectable from such measurements.…”

Optimal preparation of Bose and Fermi atomic gas mixtures of 87Rb and 40K in a crossed optical dipole trap

“…[51,52] Secondly, the hyperfine-changing collision for the combinations of 87 Rb|1, 1 + 40 K|9/2, 9/2 is a process of energy absorption and is forbidden. [53][54][55] Thirdly, the difference of heteronuclear elastic collision rates (−235a 0 and −430a 0 ) [56] is a reason for the longer lifetime. Finally, the longer lifetime of 87 Rb |1, 1 and fast thermalization of 87 Rb|1, 1 + 40 K|9/2, 9/2 are also a reason for the spin combination of 87 Rb|1, 1 + 40 K|9/2, 9/2 maintaining longer lifetimes.…”