Be sure to watch the train go by. On Thursday, Emmanuel Macron, on the Saclay Plateau near Paris, presented an investment plan of 1.8 billion euros in quantum technologies.

Goal ? “To be at least among the top three in the world,” as the President of the Republic made clear, without ruling out even a “stronger ambition.” In other words, to beat the pawn in the US or China, which are in the lead in this field.

What is the quantum?

It is an endless world of smallness: the world of atoms and particles, and at least their paradoxical properties described by quantum physics. This system was born at the beginning of the twentieth century, when we wanted to clarify the nature of light: a wave or a particle?

Taking the theories of physicist Max Planck (who introduced the idea of ​​”quantum” to designate elementary particles of energy), Einstein revolutionized the world by explaining that light was both a wave and a particle.

This double face indicates that the particles have a double behavior, and can be found in several states at the same time. An electron, for example, can be in many places at the same time … at least until we try to notice it, forcing it to “choose” a location in space.

Austrian physicist Erwin Schrödinger drew a famous thought experiment using A. The cat is both dead and alive. Two particles can also behave like one: even if they were separated by thousands of kilometers, they would change state together. This is the famous phenomenon Quantum entanglement.

In short, the quantum world is the strange world. So strange that some scientists who anticipated its anomaly, in Einstein’s mind, questioned the truth of some of the properties.

what is the point ?

Quantum physics has long been largely theoretical, and with good reason. Performing manipulations and measurements in the world of tiny things is a daunting task, and the techniques needed to do so are modern.

It took 80 years for the quantum entanglement predicted by Einstein to be confirmed conclusively in 2015. The first applications are beginning to emerge: “Today we are at a point where lab manipulations are going through the switch to prototypes,” sums up Marco Ehrman, vice president in charge of Science in Thales.

The French company hopes to commercialize the first quantum sensors within a few years. One app among many strange properties of quantum physics.

One of the most important remains the development of the quantum computer, which is able to bring today’s supercomputers to the abacus rank (see this article for detailed explanations). Several prototypes are already in place.

Another area of ​​application is cryptography: by exploiting the quirks of quantum entanglement, it is possible to create messages that are completely tamper-proof (just reading them would corrupt the data). The United States laid the foundations for the quantum internet last summer. And China, another country that invests heavily in this sector, conducted a quantum transfer between a satellite and a ground station last year.

In short, the apps are revolutionary. And it’s not just computers or communications: researchers have discovered that if geckos can climb a perfectly smooth wall, it’s because They use certain properties in quantum physics.

What does the French investment plan offer?

According to the Elysee, public funds for the amount should drop from 60 million euros to 200 million annually, which would place France in third place in the world, after China and the United States. In addition to 1.05 billion euros for the state, the envelope includes European credits (200 million euros) and expectations of the private sector (550 million).

The French plan is for it to last five years.

In detail, he plans to allocate nearly 800 million euros for computers alone, whether it is the first machines (simulations and partially quantum machines, 350 million euros) or those that will appear in the long term. (Complete quantum computers, 430 million euros). Emmanuel Macron aims for France to become “the first country to equip itself with a complete prototype of quantum computers for general purposes”.

The other envelopes will be devoted to sensors (250 million euros), post-quantum encryption (150 million euros), quantum communications (320 million euros) and related technologies that make it possible to build quantum equipment. (Refrigeration science, for example, 300 million euros).