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10 Examples of Quantum Tunneling

September 17, 2023
written by Qamar Zaman

Quantum tunneling is a phenomenon in which a particle can pass through a barrier or gap that is theoretically too high or wide for it to cross. Examples of quantum tunneling include Nuclear fusion in Stars and radioactive decay.

Examples of Quantum Tunneling

Here are 10 examples of quantum tunneling.

Image of Examples of Quantum Tunneling

1. Nuclear Fusion in Stars

Nuclear Fusion in Stars is a very common example of quantum tunneling. In stars like the Sun, quantum tunneling allows atomic nuclei to overcome the Coulomb barrier (a repulsive force due to the positive charges of protons) and fuse together to form heavier elements. This process is crucial for the star’s energy production.

2. Radioactive Decay

Quantum tunneling is responsible for the decay of certain unstable atomic nuclei. For example in alpha decay, a nucleus emits an alpha particle (two protons and two neutrons) by tunneling through the strong nuclear force barrier that holds it together.

3. Tunnel Diodes

Tunnel diodes are semiconductor devices that exploit quantum tunneling to allow electrons to pass through a thin insulating barrier. This results in a unique voltage-current relationship that finds applications in high-frequency electronics.

4. Scanning Tunneling Microscopy

Scanning Tunneling Microscopy (STM) is a powerful technique that uses quantum tunneling to image surfaces at the atomic level. A sharp metal tip hovers just above a sample surface and the current due to tunneling electrons is measured to create detailed images of atomic arrangements.

5. Quantum Dots

Quantum dots are nanoscale semiconductor particles where the confinement of electrons leads to quantum tunneling effects. They are used in various applications, including displays, solar cells, and quantum computing.

6. Tunneling Magnetoresistance

Tunneling magnetoresistance is a phenomenon that occurs in magnetic tunnel junctions. Quantum tunneling of electrons through an insulating barrier is influenced by the relative orientation of magnetic layers, leading to changes in electrical resistance. It has applications in magnetic data storage (e.g., hard drives).

7. Fusion Reactions in Particle Accelerators

In particle accelerators, high-energy particles can undergo fusion reactions when they collide. Quantum tunneling helps particles overcome the electrostatic repulsion between them, allowing for the fusion of atomic nuclei.

8. Tunneling in Chemical Reactions

Certain chemical reactions involve quantum tunneling. For example, in enzyme-catalyzed reactions, protons or electrons can tunnel through potential energy barriers, enabling reactions to occur at lower temperatures than classical chemical kinetics would predict.

9. Tunneling in Biological Processes

Quantum tunneling is implicated in some biological processes. For instance, it is theorized that quantum tunneling may play a role in processes like photosynthesis, where electrons need to overcome energy barriers to transfer energy efficiently.

10. Tunneling in Semiconductors

In semiconductor devices like flash memory cells, electrons can tunnel through thin insulating layers to either store or erase data, depending on the charge state of the memory cell.

These examples demonstrate the far-reaching implications of quantum tunneling across various scientific disciplines, from astrophysics and nuclear physics to materials science and nanotechnology.

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