What is Quantum tunneling: Definition and 128 Discussions

Quantum tunnelling or tunneling (US) is the quantum mechanical phenomenon where a wavefunction can propagate through a potential barrier.
The transmission through the barrier can be finite and depends exponentially on the barrier height and barrier width. The wavefunction may disappear on one side and reappear on the other side. The wavefunction and its first derivative are continuous. In steady-state, the probability flux in the forward direction is spatially uniform. No particle or wave is lost. Tunneling occurs with barriers of thickness around 1–3 nm and smaller.Some authors also identify the mere penetration of the wavefunction into the barrier, without transmission on the other side as a tunneling effect. Quantum tunneling is not predicted by the laws of classical mechanics where surmounting a potential barrier requires potential energy.
Quantum tunneling plays an essential role in physical phenomena, such as nuclear fusion. It has applications in the tunnel diode, quantum computing, and in the scanning tunneling microscope.
The effect was predicted in the early 20th century. Its acceptance as a general physical phenomenon came mid-century.Quantum tunneling is projected to create physical limits to the size of the transistors used in microelectronics, due to electrons being able to tunnel past transistors that are too small.Tunneling may be explained in terms of the Heisenberg uncertainty principle in that a quantum object can be known as a wave or as a particle in general. In other words, the uncertainty in the exact location of light particles allows these particles to break rules of classical mechanics and move in space without passing over the potential energy barrier.
Quantum tunnelling may be one of the mechanisms of proton decay.

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  1. K

    B Question about Hawking Radiation and Iron Stars

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  2. A

    I Looking for resources about tunneling effect on two delta functional barriers

    Hello. I have 2 questions. First, I've read theory of tunneling effect but I need theory of two and more delta functional barriers. How do you think where can I read more about it? I need it for superconductors. And second, where can I find how to add magnetic field to theory of it? How it...
  3. Kinker

    I Does gravity cause quantum decoherence?

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  4. Kinker

    B Does decoherence prevent 100% of quantum tunneling of macro object?

    Isn't the quantum tunneling probability of macroscopic objects always zero due to quantum decoherence? It may be possible in the microscopic world, but I always think it is impossible in the macroscopic world due to countless interactions. Isn't this the same in a universe with infinite time...
  5. Addez123

    Confused about quantum tunneling through 200V not eV

    I have the equations to calculate transmission probability, my problem is that the barrier is given in Volts not electron volts. $$200V = e \cdot 200 eV = 3.2 \cdot 10^{-17} eV$$ I am not even sure if that's a correct conversion. But if it is then this "barrier" is extremly small and 99.999%...
  6. Samama Fahim

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  7. M

    Quantum Tunneling to an infinite wall

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  8. A

    I Superluminal Quantum tunneling without FTL messaging

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  9. Wannabe Physicist

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  10. The Baron

    I Could Light Absorption Be Linked to Quantum Tunneling?

    Hi, I have just now started learning about quantum mechanics, and I have an Idea, which i am 99 percent sure is wrong, but i wanted to post it just in case. Okay, so I researched it a little and it turns out that the probability for a single particle to experience quantum tunneling is 0.1%...
  11. B

    B Sun powered by quantum tunneling - question

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  12. J

    I Quantum Tunneling in an STM: ELI5 Requested

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  13. J

    I Quantum Tunneling in the Sun and Conservation of Energy

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  14. wolfy

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  15. Superposed_Cat

    I Pair production via Quantum Tunneling has negative Kinetic energy?

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  16. wolfy

    B Quantum Tunneling different individual transmission probabilities

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  17. N

    I Is it possible to explain Quantum tunneling with the HUP?

    I'm a student in South Korea(It is my first English question ever). I found descriptions of quantum tunneling explained by the uncertainty principle in Korea. There are two kinds of descriptions to explain quantum tunneling; position-momentum and time-energy uncertainty principle. First...
  18. mgkii

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  19. T

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  20. S

    I Understanding Electron Behavior in Quantum Tunneling through Dielectrics

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  21. YoungPhysicist

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  22. A

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  23. SameerTahir

    I Source of energy for quantum tunneling of a particle

    If a micro-particle tunnel through a barrier which has higher potential energy than the energy of the particle, then from where does the particle get the energy to cross that barrier?
  24. E

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  25. SameerTahir

    I Concepts to understand Quantum Tunneling

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  26. PGaccount

    B Quantum Tunneling: Reflection and Transmission Probabilities Explained

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  27. N

    I Quantum Tunneling Max Distance

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  30. J

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  31. A

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  32. T

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  33. G

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  34. R

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  35. R

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  36. R

    B Exactly how quantum tunneling leads to a Big Bang?

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  37. N

    I Please help me understand quantum tunneling conceptually?

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  38. Ranku

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  39. Ranku

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    Does electroweak symmetry breaking involve quantum tunneling, just like GUT symmetry breaking?
  40. N

    I Problem of quantum tunneling and Many Worlds interpretation?

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  41. C

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  42. durant35

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  43. Alan Ezra

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  44. G

    Quantum tunneling instantaneous

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  45. P

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  46. sevenperforce

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  47. J

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  48. goat-on-a-stick

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  49. I

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  50. skulliam4

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