The closest we've gotten to absolute 0 is 0.00002K or 0.2mK using Helium 3 and 4. My theory is we will never be able to get anything to absolute 0 with out using a vacuum. Seeing that heat can be transferred from atom to atom using vibrations I would believe theoretically to get any atom to absolute 0 you would first have to isolate it then periodically send in other atoms to eat away at its vibrational energy. Maybe I'm not making sense in how I am saying this, I'm not too good at conversing ideas but hopefully some of you will catch on to my hypothesis.