Is it true that absolute zero cause large groups of atoms to blur together into a single quantum state?

Sort of. What you are talking about is a Bose-Einstein Condensate (BEC). This is not theoretical, it has been done. In fact it has been done a lot. Almost every big university will have at least one physics professor with a BEC lab. Eric Cornell, Carl Weimann and Wolfgang Ketterle won the Nobel Prize in physics about 8 years ago for experimentally producing BECs in the mid 1990's.





But there are a few things you are getting wrong. First off, this only works for Bosons. All atoms are either Bosons or Fermions, depending on their spin state. And about half of them are Bosons, which will condense into a BEC. Fermions do something else when they get very cold, which is a bit too complicated to discuss here. The second issue is that you do not need to get to absolute zero (as that is impossible). You just need to get cold enough that the average energy is lower than the some threshold set by how tight you are trapping the cloud of bosonic atoms. That means you need to get to less than a few microkelvin (less than 0.00001 K or so). To get there, they have a two step process. First, using laser cooling and what is called an optical molasses, they cool the atoms down close to this temperature. Then they allow the hottest atoms to 'boil' out of the magnetic trap that hold the cloud of atoms. This is called evaporative cooling (analogous to how your coffee cools down), and that gets the atoms to a low enough temperature for them to condense. Once they do form a BEC, they are in a single quantum state. This makes them very interesting for certain types of sensing applications (like gyroscopes or general quantum studies). Probably the most popular thing to study with BECs recently is to spin them and watch quantum vortices form in the BEC.





They are just beginning to study BECs with multiple species of atoms. But typically BECs are formed using a single type of atom (isotopically pure as well), because if the atoms are not the same, they can not really share a quantum state. Furthermore, BECs can only be performed with certain atoms that are well behaved. To be well behaved, it has to have certain magnetic properties and certain spectroscopic properties that allow it to be magnetically trapped and laser cooled with existing laser technology. There are probably about 10 types of atoms that have been used to make a BEC at this point. But, in theory, if you can cool the atoms close enough to absolute zero, you could make a BEC out of any bosonic atom. The problem is whether or not you can do that for the given atom, in practice.





But, yes, some atoms, when close to absolute zero, do condense into a single quantum state, called a BEC.Is it true that absolute zero cause large groups of atoms to blur together into a single quantum state?
We don't know. NO ONE has ever found or produced Absolute Zero. True absolute zero does not exist in nature, and has not yet been produced by scientific experiments.





What you speak of is called the Bose-Einstein Condensate. it is still theoretical, as no one has actually PROVEN it yet.





Absolute Zero is defined as the point where ALL atomic motion stops. So far, scientists have reach a point like 0.00001 degree above Absolute Zero, but there is ALWAYS some small amount of atomic motion.Is it true that absolute zero cause large groups of atoms to blur together into a single quantum state?
It's impossible to cool something to absolute zero. But yes, as you get very close, under certain circumstances one can begin to see quantum effects on a macroscopic scale. See for example, the topic of Bose-Einstein condensates.
It is the thought that, at absolute zero, all motion will cease, making everything appear at the same quantum level. However, this is only speculation, since absolute zero cannot be reached.