Interaction driven dynamics of few atoms in an optical tweezer

Mikkel

Dr. Mikkel Anderson, University of Otago
This colloquium will be held at 11 am, 13th Septemeber, in  Bldg.: Richards (05), Room #213
Abstract:
An enduring ambition in atomic physics is to build an understanding of interacting macroscopic systems from the knowledge of the underlying microscopic dynamics. We use a bottom-up approach to assemble individual few-atom systems in an optical micro-tweezer and study their dynamics. This allows for interrogation of atoms with collisional properties that are unfavourable for many-body experiments as well as direct observation of effects that get hidden by ensemble averaging.
The talk will present the results of our recent studies of the dynamics of three different atomic interactions. From precisely two atoms we build individual molecules in particular quantum states using photo-association. The experiment reveals that the dynamics of this process is more complex than when photo-associating molecules in a large sample of atoms.
Next, we studied the spin-dynamics of two thermal spin-two atoms undergoing spin-changing collisions in the optical tweezer. We see that it leaves the magnetic sub-levels of the atoms strongly correlated with relative number fluctuations 11.9 dB below quantum shot noise. The observed dynamics may provide a route for thermally robust entanglement generation.
Finally, in an experiment with a cold Rb-85 triad, we observe three-body recombination. Our ability to directly observe the number of atoms remaining after individual loss events allow us to discriminate between one-two- and three-body loss events. However, we also observe that the three-body recombination rate is strongly suppressed relative to the expected rate for non-interacting atoms. This could indicate that interactions between the atoms induce correlations that suppress three-body recombination despite Rb-85 having effective attractive interactions with a negative scattering length.