Dropping Balls Into a Valley: What is Quantum Tunneling?

Explainer: What is quantum tunneling?

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+  According to quantum rules, electrons can behave both as a particle and a wave, and objects can be in different states at once – a phenomenon quantum computers use to their advantage. One of the strangest things scientists discovered when picking apart quantum mathematics is tunneling.

Jack Fraser, a physics graduate from the University of Oxford wrote: ‘You could get a trillion people walking into walls, a trillion times every second since the beginning of the universe [13.8 billion years ago] – and the likelihood of one of them walking through the wall is still so small, it’s [practically] zero.’

+  Imagine releasing a quantum mechanical particle, like an electron or proton, into a space on one side of an potential energy hill. Since you’re sure that the particle can’t escape – it’s not energetic enough to climb over the hill – you leave it to its own devices.

+  But when you go back to check on it, the particle is gone. You find it happily sitting on the other side of the hill, having sneaked straight through it. Tunnelling particles can simply pass through energy barriers they don’t have the energy to surmount.

Source:  Royal Society of Chemistry.  Katrina Krämer,  Explainer: What is quantum tunneling?

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