Seminarium Optyczne

In recent years, a novel field of physics and chemistry has developedin which trapped ions and ultracold atomic gases are made to interactwith each other. These systems find applications in studying quantumchemistry and collisions [1], and a number of quantum applications areenvisioned such as ultracold buffergas cooling of the trapped ionquantum computer and quantum simulation of fermion-phonon coupling[2]. Up until now, however, the ultracold temperatures required forthese applications have not been reached, because the electric trapsused to hold the ions cause heating during atom-ion collisions [3]. Inour experiment, we overlap a cloud of ultracold 6Li atoms in a dipoletrap with a 171Yb+ ion in a Paul trap. The large mass ratio of thiscombination allows us to suppress trap-induced heating. For the veryfirst time, we buffer gas-cooled a single Yb+ ion to temperaturesclose to the quantum (or s-wave) limit for 6Li-Yb+ collisions. We findsignificant deviations from classical predictions for the temperaturedependence of the spin exchange rates in these collisions. Our resultsopen up the possibility to study trapped atom-ion mixtures in thequantum regime for the first time. Finally, I will present a novel wayto control interactions between atoms and ions, that employsRydberg-coupling of the atoms to tune their polarizability [4,5].[1] M Tomza et al., arXiv:1708.07832 (2017).[2] U. Bissbort et al., Phys. Rev. Lett. 111, 080501 (2013).[3] M. Cetina et al., Phys. Rev. Lett. 109, 253201 (2012).[4] T. Secker et al., Phys. Rev. Lett. 118, 263201 (2017).[5] N. Ewald et al., arXiv:1809.03987 (2018).