kvanttitunneloitumisen

Kvanttitunneloitumisen is a quantum mechanical phenomenon where a particle can pass through a potential energy barrier even if it does not have enough energy to overcome it classically. Imagine a ball rolling towards a hill. Classically, if the ball doesn't have enough speed to reach the top, it will roll back down. However, in the quantum world, there's a small but non-zero probability that the ball could simply appear on the other side of the hill, as if it tunneled through it.

This effect arises from the wave-like nature of quantum particles. According to quantum mechanics, particles are not just points but also have wave properties, described by a wave function. This wave function doesn't abruptly drop to zero at a potential barrier but extends into it and even slightly beyond. The probability of finding the particle on the other side of the barrier is related to the amplitude of this wave function on the far side.

The probability of tunneling depends on several factors. A thinner and lower barrier increases the tunneling probability, while a thicker and higher barrier decreases it. The mass of the particle also plays a role; lighter particles tunnel more readily than heavier ones.

Kvanttitunneloitumisen has significant practical applications. It is fundamental to the operation of scanning tunneling microscopes (STM), which can image surfaces at the atomic level by measuring the tunneling current between a sharp tip and the sample. It also plays a role in semiconductor devices like tunnel diodes, and is crucial for nuclear fusion in stars, as protons can tunnel through their mutual electrostatic repulsion to fuse. Radioactive alpha decay is another phenomenon explained by quantum tunneling.