Re: What, if any, would be the creatable conditions for atomic tunneling?

Quantum tunneling is a common occurence for most particles and groups of 
nucleons. The typical example of tunneling in nature is the emission of 
alpha-particles [which are ionized Helium nuclei, He (2+)] from radioactive 
nuclei.
  The obvious laboratory use of tunneling is in the Scanning Tunneling 
Microscope. This is used to image surfaces of conducting materials by 
utilising what is called a "tunneling current", which is in essence the 
picking up of electrons tunneling out of the material under study.

As for the tunneling of whole atoms, I haven't been able to find any work 
on it as yet. I see a few problems with doing it immediately. Mainly, 
getting single atoms is not an easy task, and if you have a few atoms all 
together then there is another process that is the macroscopic (large 
scale) equivalent of quantum tunneling and could easily masquerade as it. 
This process is produced by the Boltzmann distribution, which tells you 
about the momentum distribution in a collection of objects. This 
distribution shows that for a group of objects at a certain temperature, 
most of the objects have an energy equivalent to the temperature of the 
overall group, but there are also objects with a less energy, and (this is 
the important part) objects with more energy than the average.

This tail on the Boltzmann distribution is the cause for the slow 
disappearance of our atmosphere in to space. The hotter molecules of gas 
escape from the earths gravity, taking with it energy, and making the 
atmosphere look cooler. (but no matter how cool it gets, the Boltzmann 
"tail" is still there. The lower temperature only means that the chance a 
molecule has the higher energy is lower.) 

Of course, the common name for this process is Evaporation.

There are probably other reasons as well. This doesn't mean that tunneling 
of atoms doesn't take place and that it hasn't been seen in a lab. It 
almost certainly does take place regularly in nature. And I may just not 
have found the right journal article yet.

I hope this helps you some. If you'd like to contact me directly about it, 
please email me at drichar2@williams.edu. The same goes for anyone out 
there that knows of actual experiments that utilise tunneling atoms. If you 
know of any, please contact me, I would like to correct myself if I'm 
wrong.