Quantum mechanics at the origin of our future computers

Rectangular glasses on his nose, a V-neck sweater for uniform, physicist Michel Devoret does not have the crazy look of the brilliant Albert Einstein. However, it will mark the history of science. At the beginning of October, the 72-year-old Frenchman made France proud by winning the 2025 Physics Nobel alongside the British John Clarke and the American John Martinis. A prize which recognizes work making it possible to master quantum laws at the heart of tiny circuits, a decisive step towards the computer of the future.

To measure the feat, you have to immerse yourself in a world that studies the infinitely small. In this universe of atoms and particles, the laws of physics seem to defy common sense. “Most people don’t understand much about it,” observes Mi-Song Dupuy, mathematician at Sorbonne University. It’s normal! Quantum mechanics applies to phenomena that have nothing to do with everyday life.” However, it is at the origin of all modern electronics – smartphones, televisions, etc. – because it explains how electrons circulate.

A theory that only applies on the microscopic scale

At the beginning of the 20th century, Albert Einstein revealed to us this astonishing but true theory: light is both a particle (the tiniest part of a body) and a wave (a movement which propagates and transports energy). A microscopic object can therefore be in several states at the same time, be in different places at the same time. “For example, when you throw a ball against a wall, the ball bounces,” says Mi-Song Dupuy. In quantum physics, one of its particles can pass through the wall.”

In 1935, the Austrian Erwin Schrödinger illustrated this paradox with a cat locked in a box containing poison. According to quantum mechanics, the cat can be dead and alive at the same time. Schrödinger gently made fun of us. In fact, he sought to show us that what applies on the microscopic scale cannot apply to the full-scale world.

We must therefore redouble our inventiveness to unlock the secrets of quantum physics. Michel Devoret, a big fan of cinema and comics, immersed himself in it very early. First a member of the Paris-Saclay research center, in Essonne, the young researcher flew to the United States in 1982.

The American University of California and then that of Yale offer more resources, cutting-edge laboratories and international collaborations. In California, Michel Devoret and his colleagues have identified a breathtaking phenomenon: the tunnel effect, when a particle crosses an impassable barrier.

A global competition

This discovery allowed researchers to lay the foundations for quantum computers. These machines could solve several simultaneous operations that our current supercomputers would process in several millennia.

For now, they are making too many mistakes to be marketed. But the global competition is open. In France, an ecosystem of start-ups is growing while the American company IBM announces a reliable computer from 2029.

Today, quantum technologies already exist in medical imaging, the detection of dangerous substances or atmospheric molecules. But the near future promises us a revolution. Thanks to hyper-powerful computers, we will be able to better prepare for natural disasters and anticipate evacuation scenarios. In the event of war, these machines will detect bases and submarines, and decipher enemy communications.

But we will also be able to thwart cyberattacks, improve our logistics networks and identify new molecules to design drugs more quickly. Thanks to the world of the infinitely small, the horizon looks infinitely large. Let us hope that these tools serve man and not the other way around.