PlanetPhysics/Efimov States

Efimov states
The Efimov states were initially proposed in 1970 as hypothetical, stable quantum states of coupled three-body systems such as three coupled bosons in ultracold `gedanken experiments'. A most interesting feature of such ultracold 3-boson systems was the presence of an infinite number of Efimov states when the boson coupling was weak but finite when the coupling became strong.

Subsequently, in 2006, there have been published claims of experiments indicating the presence of such "Efimov trimers" .(See also the following references.)