Quantum Optics Seminar by Johannes Hecker Denschlag – Niels Bohr Institute - University of Copenhagen

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Quantum Optics Seminar by Johannes Hecker Denschlag

I would like to introduce you to an experiment where we bring into contact a cloud of ultracold neutral atoms and trapped ions.  The dynamics of this two-species mixture is dominated by an attractive 1/r4 polarization potential between ion and atom. We investigate elastic and inelastic collisions, as well as reactions of the ion with the neutral atoms. One such reaction is a three-body recombination of a single trapped Rb+ ion and two neutral Rb atoms [1]. In the three-body recombination process large energies up to several 0.1eV are released leading to an ejection of the ion from the atom cloud. It is sympathetically recooled back into the cloud via elastic binary collisions with cold atoms. We find that the final ionic product of the three-body processes is again an atomic Rb+ ion, suggesting that the ion merely acts as a catalyzer.

Furthermore, we have recently used our setup to also investigate three-body recombination of three neutral Rb atoms, where a Rb2 molecule is formed. We are able to study for the first time in detail which vibrational, rotational, and hyperfine quantum states of the Rb2 molecule are populated in this process. 

[1] A. Härter, A. Krükow, A. Brunner, W. Schnitzler, S. Schmid, J. Hecker Denschlag, Phys. Rev. Lett. 109, 123201. (2012).