We will have Henning Fürst, currently works in the group of Rene Gerritsma at the University of Amsterdam as our guest.

He will give a talk on October, 15th at 10 am in RZB11 at PTB.

Guests are welcome

Details on his presentation:

Trapped ions in a bath of ultracold atoms

Recent years have seen significant interest in coupling ultracold atomic and ionic systems with the purpose of studying quantum many-body physics, and collisions, or employing ultracold gases to sympathetically cool trapped ions [1]. However, up until now it has proven impossible to reach the quantum (s-wave) regime of interacting atoms and ions. This is because the Paul traps used for storing the ions can add energy to the system when ion-atom collisions occur. It was shown that this effect can be mitigated by employing an ion-atom combination with a large mass ratio [2]. In my talk, I will describe a new experimental setup that we build to overlap Yb+ ions with 6Li atoms. This combination has the highest mass ratio of all species that allow for straight-forward laser cooling. We observe the spin dynamics of a single trapped Yb+ ion in a cold gas 6Li atoms. We observe rapid spin dynamics, indicating a large spin-exchange cross section. We compare our data to quantum scattering calculations and find that the fast spin exchange can be explained by a large difference between singlet and triplet scattering length, suggesting the existence of broad Feshbach resonances [3] in the quantum regime. We estimate the accessibility of reaching this regime within our experiment. For the atoms, we present recent data on the preparation of an ultracold atomic sample of 6Li atoms within our Paul trap. For the ions, we perform numerical simulations of trapped 171Yb + ions in a buffer gas of ultracold 6Li atoms [4]. Using our experimental trapping conditions, we compute that the collision energy indeed reaches below the quantum limit a perfect Paul trap. The suppression of excess micromotion, required to remain within the quantum regime, should be within experimental reach [5].

[1] M. Tomza et al., ArXiv e-prints, arXiv:1708.07832 (2017)
[2] M. Cetina et al., Phys. Rev. Lett. 109, 253201 (2012)
[3] H. Fürst et al., Phys. Rev. A 98, 012713 (2017)
[4] H. Fürst et al., accepted in J. Phys. B, arXiv:1804.04486 (2018)
[5] A. Härter et al., Contemp. Phys. 55, 33–45 (2014)