Quantum Tunneling

NetMage

So I've been reading up on some quantum tunneling. It seems as though everything I read on it only conveys an elementary view on the matter, as if their target audience was the general public. I am here to gain a more sophisticated understanding of this concept. As I currently understand quantum tunneling is the effect of particles colliding at high speeds as to where the mechanical energy is greater than the potential energy of the barrier and in QM there is probability that the particle will appear on the other side [I]regardless of the width of the object?![I] Why is there not a chance that the particle could appear inside the object? Has there been successful studies done on this? Does this constitute possibilities in teleportation/information sending?

Drakkith

Actually, it is where the mechanical energy is LOWER than the potential energy of the barrier.

NetMage

Oops, my mistake. Typo**

Drakkith

Also, i believe that particles that tunnel through something will not appear "Inside" another particle, as they cant occupy the same space. And quantum tunneling can also be used to explain when a particles overcomes a force that it shouldnt have. Such as being able to fuse atoms together at a lower energy than should be possible. Quantum tunneling can do this sometimes.

NetMage

Ok, but if a particle cant appear inside space that is being occupied...isnt even the 'space' on the other side of the object still being occupied by other particles...for instance, air is still composed of particles that is occupying that space.

Drakkith

Air is mostly empty space with atoms/molecules just whizzing through it.

alxm

Two particles can occupy the same space just fine. Two fermions with the same spin and energy cannot.

ZapperZ

The other thing that's wrong is that the particles are (i) not moving at high speeds and (ii) not "colliding". A collision will cause a loss of coherence. In fact in many instances, scattering effect will diminish the tunneling current.

Secondly, in many tunneling experiments, the "speed" is very small when one considers that the applied voltage across the tunneling barrier is on the order of millivolts!

Zz.

NetMage

Hm, well this is a bizzare concept. So it is to say that it is complete random chance that if the mechanical energy is less than the barrier that it will simply appear on the other side? What about time elapsed during the particle appearing on the other side? Is this instantaneous? Does this constitute FTL if so?

Drakkith

I have no idea on this one.