So, what is it?
It's a bound state of 3 identical bosons that happen even if the force between any two of the bosons is not strong enough to cause binding.
In other words, these states only appear when you have 3 bosons, take any one away and the whole system disappears.
Efimov States have an infinite series of excited three-body energy levels.
They are often depicted symbolically by the Borromean rings - no two rings are linked, but all 3 rings are linked!
Content written and posted by Ken Abbott abbottsystems@gmail.com