Optically trapping and isolating atoms and ions
Prof. Dr. Tobias Schätz (Physikalisches Institut der Universität Freiburg)

Isolating ions and atoms from the environment is essential in experiments on a quantum level. For decades, this has been achieved by trapping ions with radiofrequency (rf) fields and neutral particles with optical fields. Our group demonstrated the trapping of ions by interaction with light [1,2,3]. We take these results as starting point for finally combining the advantages of optical trapping and ions [4]. In particular, ions provide individual addressability, high fidelities of operations and long-range Coulomb interaction, significantly larger compared to those of atoms and molecules.

We aim to demonstrate the prospects of our approach in the context of interaction and reaction at ultra-low temperatures as a showcase. Following the seminal work in the groups of Vuletic, Koehl and Denschlag in hybrid traps, we plan to embed optically trapped ions into quantum degenerate gases to reach lowest temperatures, circumventing the currently inevitable excess kinetic energy in hybrid traps, where ions are kept but also driven by rf-fields [5]. It might permit to enter the temperature regime where quantum effects are predicted to dominate, (i) in many-body physics, including the potential formation and dynamics of mesoscopic clusters of atoms of a BEC, binding to the impurity ion, as well as (ii) the subsequent two-particle s-wave collisions, the ultimate limit in ultra-cold chemistry. We will report about our recent results [6] on optically trapping 138Ba+ in a bi-chromatic far-off-resonant dipole trap sufficiently isolated and providing lifetimes of seconds. In addition, we aim to discuss the prospects for Coulomb Crystals within optical traps.

[1] C.Schneider, M.Enderlein, T.Huber, and T.Schaetz, Nature Photonics 4, 772 (2010).
[2] M.Enderlein, T.Huber, C.Schneider, and T.Schaetz, Phys. Rev. Lett. 109, 233004 (2012).
[3] T.Huber, A.Lambrecht, J.Schmidt, L.Karpa, T.Schaetz, Nature Communications, 5 (2014).
[4] C.Schneider, D.Porras, and T.Schaetz, Reports on Progress in Physics 75, 024401 (2012).
[5] M.Cetina, A.T.Grier, and V.Vuletic, Phys. Rev. Lett. 109, 253201 (2012).
[6] A. Lambrecht, J. Schmidt, P. Weckesser, M. Debatin, L. Karpa, T. Schaetz, arXiv:1609.06429v2 (2016)