Quantum tunneling is a fascinating phenomenon that occurs in the quantum world, where particles can pass through a potential energy barrier even if their energy is less than the barrier height. In classical physics, this would be impossible, as particles would be reflected by the barrier if their energy was not sufficient to overcome it. However, in the quantum world, particles can exhibit wave-like behavior, allowing them to pass through the barrier as if it wasn't there. In this blog, we'll explore what quantum tunneling is and some real-life examples of its occurrence.


What is Quantum Tunneling?

Quantum tunneling is a quantum mechanical phenomenon where a particle, such as an electron or an atom, can pass through a potential energy barrier even when its energy is less than the barrier height. In classical physics, a particle would be reflected by the barrier if its energy was not sufficient to overcome it. However, in the quantum world, particles can exhibit wave-like behavior, allowing them to pass through the barrier as if it wasn't there.

The probability of a particle tunneling through a barrier is determined by the thickness and height of the barrier, as well as the energy of the particle. As the barrier gets thinner or the energy of the particle increases, the probability of tunneling increases. Conversely, as the barrier gets thicker or the energy of the particle decreases, the probability of tunneling decreases.

Real-Life Examples of Quantum Tunneling of Molecules

  1. Enzyme-Catalyzed Reactions: Enzymes are biological molecules that catalyze chemical reactions by lowering the activation energy required for the reaction to occur. Quantum tunneling has been found to play an important role in some enzyme-catalyzed reactions, including the reaction catalyzed by the enzyme methylamine dehydrogenase.

  2. Hydrogen Transfer in DNA: DNA is composed of nucleotides, which are linked together by hydrogen bonds. In some cases, hydrogen atoms can transfer between nucleotides through a process known as proton tunneling. This phenomenon has been observed in experiments, and it is thought to play a role in DNA replication and repair.

  3. Scanning Tunneling Microscopy: Scanning tunneling microscopy is a technique that allows scientists to image surfaces at the atomic level. This technique relies on the quantum tunneling of electrons between a sharp tip and a surface. By measuring the current that flows between the tip and the surface, scientists can create an image of the surface with atomic resolution.

  4. Molecular Electronics: In molecular electronics, molecules are used as electronic components. Quantum tunneling plays a critical role in the operation of these devices, as it allows electrons to tunnel through potential barriers in the molecules. This effect is exploited to create molecular transistors, diodes, and other electronic components.

Conclusion

Quantum tunneling is a fundamental aspect of quantum mechanics that has many real-world applications. It is a fascinating phenomenon that allows particles to pass through potential energy barriers as if they weren't there. Enzyme-catalyzed reactions, hydrogen transfer in DNA, scanning tunneling microscopy, and molecular electronics are just a few examples of systems where quantum tunneling has been observed. Understanding and controlling quantum tunneling is critical for the development of new technologies and for a better understanding of the quantum world.