The 2025 physics prize – Quantum properties on a human scale

The 2025 physics prize is about quantum mechanics. The laureates are recognised for experiments that demonstrate quantum mechanical effects in electrical circuits.

Quantum mechanics – a strange world

Atom — Quantum mechanics describes how an electron may be located at different levels around an atomic nucleus. Photo: Creative Commons Attribution-Share Alike 3.0 Unported

Quantum mechanics is a theory that was developed about 100 years ago and which presented a completely new way of describing the world.

Tunnelling

Illustration of someone throwing a ball against the wall. — If you throw a ball against a wall in our everyday reality, it will always bounce back. If quantum mechanics were to be applied on our everyday scale, the ball would sometimes go right through the wall. © Johan Jarnestad/The Royal Swedish Academy of Sciences

Illustration of a power switch — Do you notice anything strange about this image of a power switch? That’s right, it shouldn’t be possible to move the levers. Figuratively speaking, however, the laureates’ experiments show that the lever may suddenly end up in the opposite position. ©Johan Jarnestad/The Royal Swedish Academy of Sciences

One of the effects of quantum mechanics is tunnelling. This means that barriers that should actually be impossible to pass through, may still sometimes be traversed. For example, a piece of the atomic nucleus may sometimes split off from the rest of the nucleus, even though the forces holding the atomic nucleus together should, in fact, be too strong.

The laureates wanted to show that tunnelling may occur not only among individual atoms and electrons but also on the scale in which we perceive reality, such as in an electrical circuit.

Superconductivity and tunnelling

Illustration tunnelling — 1. In a regular conductor, electrons jostle with each other and with atoms. This causes resistance.
2. In a superconducting state, the electrons form pairs, and the current may flow without resistance. But an insulating gap may stop the current.
3. A large number of pairs of electrons may sometimes behave like a single particle. This enables a current to tunnel across the insulating gap. ©Johan Jarnestad/The Royal Swedish Academy of Sciences

In the laureates’ experiments, another phenomenon enters the picture – superconductivity. Superconductivity means that a current flows without encountering any resistance whatsoever. This only happens at very low temperatures, close to absolute zero at about minus 273 degrees Celsius or minus 460 degrees Fahrenheit.

In their experiments, the laureates were able to show that tunnelling may occur in an electrical circuit with two superconductors separated by an insulating gap.

What is new in their discoveries is that quantum mechanical effects manifested themselves on our everyday scale: in an electrical circuit that we can see with our naked eyes and hold in our hands.

The 2025 Nobel Prize laureates in physics

Illustrations of the Nobel Prize laureates in Physics 2025 — The 2025 Nobel Prize laureates in physics: John Clarke, Michel Devoret and John Martinis. Ill. Niklas Elmehed © Nobel Prize Outreach

The three physics laureates jointly conducted the experiments that led to 2025 physics prize. These experiments were carried out some 40 years ago. John Clarke was born in the United Kingdom but carried out research at the University of California, Berkeley, in the 1980s. His research group was joined by Michel Devoret, a Frenchman who had recently completed his doctoral studies in Paris. The group also included the American John Martinis, who was still engaged in his doctoral studies when these experiments were carried out.

What could these discoveries lead to?

These discoveries have played and will play an important role in research by offering a better understanding of how quantum mechanical systems behave.

In the future, these discoveries may also have an impact on the development of quantum computers, which will be much more powerful than current computers, quantum sensors, which may result in more sensitive measuring instruments, and quantum encryption technologies, which may offer more secure ways of storing and transmitting data.

In this short video, you will learn a little bit more about the discoveries made by the laureates and why they confer the greatest benefit to humankind: