Atoms and Ions commonly trapped by light – towards chemistry at the Nano-Kelvin level
Prof. Dr. Tobias Schätz (Albert-Ludwigs-Universität Freiburg)

How are chemical reactions proceeding at lowest temperatures? The classical concept predicts that approaching zero velocity is equivalent to standstill of any dynamics. On the one hand, it became already common sense that the classical model is ceasing to be appropriate when particle-wave dualism is gaining of importance. On the other hand, we might be inclined to see quantum mechanical properties as minor corrections only - such as the uncertainty principle allowing for some minor residual interaction. However, in the regime where quantum effects dominate, chemistry is predicted to obey fundamentally different rules. Examples are:
(i) collisions of two species, necessary for a reaction, cannot be described as a billiard-like impact between hard spheres anymore, but rather as interfering waves which can coherently amplify or even completely annihilate each other - subjected to long range interaction. (ii) energy barriers do not have to remain smaller than the residual kinetic energy, but can be efficiently passed by tunneling. As a consequence and vision, quantum chemistry might permit to manipulate or even control reactions and their pathways by external fields, since the forces and related interactions become relevant compared to the kinetic energy.

We follow the approach, pioneered by a group at MIT in 2009, to exploit the unique control of trapped ions and atoms towards investigating these interactions on the quantum level. We aim to overcome the limitation revealed in the current experimental realizations that are attested to be fundamental, inherently related to the combination of radio-frequency (rf)-traps for the ion with optical traps for atoms.
Based on our recent experimental results on optically trapping an ion, we propose to combine the advantages of ions and atoms (as BEC at 100nK), trapped in a common optical trap. We propose our protocol to reach beyond chemical processes where still many partial waves contribute, that is, to explore the essence of the quantum dynamics.
On longer time scales, we want to extend our approach to explore and exploit the advantages of combining neutral and charged atoms in common optical traps and optical lattices, to further enhance the method to the single atom, single ion level, as well as venturing other fields of research, such as analog quantum simulations.