Question

What is the principle of tunneling?

Answer 1

Tunneling is a quantum mechanical phenomenon where particles move through a barrier that they would not be able to pass if we were considering classical physics. In classical physics, if a particle doesn't have enough energy to overcome a barrier, it would just be stopped by the barrier. However, in quantum mechanics, particles like electrons have wave-like properties, and there is a small probability that they can "tunnel" through the barrier, even if they don’t have enough energy to overcome it.

This happens because the particle is described by a wavefunction, which gives the probability of finding the particle at a particular position. The wavefunction doesn't abruptly go to zero at a barrier; instead, it decays as it enters the barrier but doesn't vanish completely. This means there's still a non-zero chance that the particle can appear on the other side of the barrier, effectively "tunneling" through it.

The principle of tunneling has important applications, such as in:

1. Tunnel Diodes: Used in electronics where the current flows even when the voltage is below the normal threshold.
   

1. Nuclear Fusion: In stars, fusion occurs because particles tunnel through energy barriers, which is why stars can burn at temperatures lower than what classical physics would predict.
   

1. Scanning Tunneling Microscopes (STM): This technology allows us to view individual atoms by utilizing tunneling to measure the interaction between a sharp probe and a surface at a very small scale.
   

In simple terms, tunneling shows that quantum particles can "break the rules" of classical physics and appear where they normally wouldn’t be expected.