Three US researchers have won the 2025 Nobel Prize in Physics for their groundbreaking work on quantum tunnelling, a phenomenon that allows particles to pass through energy barriers.
Their experiments have paved the way for advancements in quantum technology, including quantum computers and sensors.
It highlights the ongoing relevance and utility of quantum mechanics in digital technology.
Three researchers from the United States have bagged the 2025 Nobel Prize in Physics for revealing the quantum world in action. The winners are John Clarke, University of California, Berkeley, Michel H Devoret, Yale University, New Haven and University of California, Santa Barbara, and John M Martinis from the University of California, Santa Barbara.
The trio have been recognised for their experiments showing quantum tunnelling on a macroscopic scale, involving many particles. Quantum tunnelling is a phenomenon that enables elementary particles and atoms to cross an energy barrier without the need for sufficient energy to overcome it.
This is not expected in the macroscopic world, involving many particles. For example, when a ball, which is built up of an astronomical number of molecules, is thrown at a wall, it will bounce back every time. A single particle, however, will sometimes pass straight through an equivalent barrier in its microscopic world and appear on the other side. This quantum mechanical phenomenon is called tunnelling.
Tunnelling was discovered in the 1920s by physicist George Gamow, who found that it is the reason why some heavy atomic nuclei tend to decay in a particular manner. When a small piece of atomic nucleus splits off, they move outside the barrier and breaks free, leaving behind a nucleus that has been transformed into another element. Without tunnelling, this type of nuclear decay could not occur.
To understand whether it is possible to investigate a type of tunnelling that involves more than one particle at a time, Clarke, Devoret and Martinis devised experiments at the University of California, Berkeley in 1984 and 1985. They built an electrical circuit with two superconductors, components that allow the flow of current without resistance below a certain critical temperature. They then separated the superconductors with a thin layer of material that did not conduct any current at all.
Next, they fed a weak current and measured the voltage, which was initially zero as the system was trapped in a state that it could not cross. However, the system showed its quantum character by escaping the zero-voltage state through tunnelling through the appearance of a voltage.
Further, the trio also showed that the system behaves in the manner predicted by quantum mechanics: The system is quantised, which means it only absorbs or emits specific amounts of energy. “It is wonderful to be able to celebrate the way that century-old quantum mechanics continually offers new surprises. It is also enormously useful, as quantum mechanics is the foundation of all digital technology,” Olle Eriksson, chair of the Nobel Committee for Physics, said in a statement. An example of quantum technology is computer microchips.
Their work has provided opportunities for developing the next generation of quantum technology, including quantum cryptography, quantum computers and quantum sensors, read a statement from The Royal Swedish Academy of Sciences.
This is not the first time that quantum has been recognised. In 2023, Moungi G Bawendi, Louis E Brus and Aleksey Yekimov won the Nobel Prize in Chemistry 2023 for their discovery and development of quantum dots, which are tiny particles whose characteristics are determined by quantum effects. Quantum dots have found applications in television screens and LED lamps, to name a few.