quantum tunneling

American  

[kwahn-tuhm tuhn-uhl-ing] / ˈkwɑn təm ˈtʌn əl ɪŋ /

noun

1. Physics. any of various phenomena of quantum mechanics in which a particle passes through a potential barrier that, according to classical mechanics, requires more energy to penetrate than the particle in fact possesses.

---

quantum tunneling Scientific  

1. A quantum mechanical effect in which particles have a finite probability of crossing an energy barrier, such as the energy needed to break a bond with another particle, even though the particle's energy is less than the energy barrier. Quantum tunneling has no counterpart in classical mechanics, in which a particle can never cross an energy barrier with a higher energy level than the particle has. The emission of alpha rays in radioactive decay is a case of quantum tunneling; though the alpha particles are strongly bound to the nucleus and don't have as much energy as the bond does, they still have a finite probability of escaping the nucleus. The design of transistors and many diodes makes use of this effect.

2. See also radioactivity

---

Example Sentences

In addition to quantum tunneling, the new research shows a co-tunneling effect, in which groups of tunneling electrons are communicating with each other to drive the electron spins to flip in the same direction.

From Science Daily • Mar. 28, 2024

But even though the idea behind quantum tunneling is now nearly a century old, bringing theory and experiment together to observe tunneling in chemical reactions has proved tricky.

From Scientific American • Apr. 4, 2023

If a proton spontaneously jumped out of its atomic bonds, in what physicists call "quantum tunneling," this could cause a cascade of sudden neuron activity.

From Salon • Apr. 30, 2021

General relativity explains black holes, the bending of light and "even offers a possible explanation of the origin of our Universe - as quantum tunneling from 'nothing,'" he writes.

From Reuters • Jan. 15, 2012

That suggests that even as thermal fluctuations grow too weak to nudge the system over the energy barrier, quantum tunneling remains to allow the qubit through it.

From Science Magazine • May 13, 2011