Rydberg molecules are like a pair of dancers holding hands at arm's length. One partner is an ion, the other is an atom, and the bond between them is as weak as an invisible thread. Such a pair can exist for only an instant, but that instant stretches into microseconds — an eternity by the standards of the microworld.
Scientists have calculated how quickly such molecules, made of rubidium and lithium, fall apart. It turns out that the decay rate doesn't change smoothly but in jumps, depending on the quantum number n. This is like a pendulum swinging now stronger, now weaker in time with external pushes. The reason is quantum interference: probability waves alternately amplify and cancel each other out.
Such calculations will help experimentalists observe molecular decay in real time using an ion microscope. It's like filming a sandcastle as it crumbles — except instead of sand, you have quantum waves.
Rydberg molecules were predicted back in 2000, but were first created in the lab only in 2016.