Yeah I think I figured it out.
They say that in positive temperatures - hotter values expel energy out into colder ones. Duh, leave a bowl of hot soup in the cold air and they reach equilibrium because the soup's heat escapes into the environment.
So you have negative temperatures - which always expel energy into positive values. So they will always loose energy when around any temperature above absolute zero, all the way into infinity. This does not mean it is any hotter than positive temperatures, it just means they loose energy.
The experiment limited the amount of potential energy, and restricted the amount of kinetic energy of the atoms using lasers. So they changed something with the atoms to make them attract to each other. This SOMEHOW changes the way energy is expelled.
So yeah, I won't pretend to know it, but I understand it. I guess it is the anti-particle equivalent to temperatures.
That loop analogy..SUCKED. Think of a number line, -10, -5, 0, 5, 10. There still is nothing colder than 0 because the negatives just explain how energy moves in the system. You can't have a negative speed or a temperature above infinity - both are paradoxes.
I hope I got that right.