Halo trimers and dimer–trimer superpositions
A famous phenomenon in quantum mechanics is quantum superposition: a particle can be in different states at the same time. In our recent arXiv paper we show that this idea can go as far as molecules existing in superpositions of different particle numbers.
The key ingredient is immersion in a “quantum solvent”: a Bose–Einstein condensate (BEC) of ultracold Na atoms. When we immerse K atoms in this BEC under the right conditions, coherent exchange of atoms with the condensate naturally leads to coherent superpositions of a free K atom, a NaK molecule, and a Na₂K trimer.
The existence of the trimer state by itself, we only recently discovered. It is called a “halo” trimer due to its very weak binding: it is so loosely bound that its size is comparable to that of a small bacterium.
