Hybrid ion-atom systems: exploring ion-molecule collisions and prospects for getting colder*

Both trapped ions and ultracold atoms are excellent systems for studying quantum many-body physics and quantum information applications. Combining the two opens up a new field with rich physics [1], giving us the possibility to study impurity-bath interactions, quantum chemistry, and buffer gas cooling. In our experiment [2] we have an Yb+ ion in an ultracold bath of fermionic Li atoms, with collision energies reaching the s-wave regime [3]. In this poster we present the prospects and approaches for new experiments in such a system. We theoretically explore the dynamics of a charged impurity in a bath of Feshbach dimers [4] and find a crossover from dimer dissociation to molecular ion formation. This could provide a new approach for creating molecular ions. Further, we explore buffer gas cooling of a trapped ion by ultracold atoms. Here we present the theoretical optimal parameters for reaching deeper into the quantum regime in our system, as well as comparing the suitability of different time-dependent ion traps. Obtaining lower atom-ion collision energies will put our experiment in a regime where we could expect to observe atom-ion Feshbach resonances.

[1] M. Tomza et al. Rev. Mod. Phys. 91, 035001 (2019).

[2] H. Hirzler et al. Phys. Rev. A 102, 033109 (2020).

[3] T. Feldker et al. Nat. Phys. 4, 16 (2020).

[4] H. Hirzler et al. Phys. Rev. Research 2, 033232 (2020).