In summer 2oo5, we observed the first experimental signature of an Efimov quantum state in an ultracold gas of cesium atoms. This work was the starting point for a new branch in cold-atom physics.
Here are the major milestones of our work on Efimov states:
2009: Observation of an atom-dimer Efimov resonance
Knoop et al., Nat. Phys. 5, 227 (2009)
2011: Three-body parameter universality
Berninger et al., Phys. Rev. Lett. 107, 120401 (2011)
For a very basic introduction into Efimov physics, watch the following video (produced to promote a 2017 review article by P. Naidon and S. Endo):