I wrote: In some cases photons will tunnel through a barrier between the two prisms > without refraction. If I have understood what I have read, this tunneling > is thought to occur instantaneously, in contrast to the situation where the > photon exits one prism, travels through the air and enters the other prism. >
Correction: the tunnelling time tends towards constant time for large gaps between the barriers, and hence appears to exceed the speed of light in some cases. This is different from saying that the tunneling time is instantaneous. Eric
