a discovery rewarded with the Nobel Prize in Physics in 2022

⇧ [VIDÉO] You might also like this partner content (post ad)

Advances in quantum physics are only challenging all of our beliefs about the world around us. The Nobel Prize in Physics this year rewards a trio of researchers who, after 50 years of work, have irrefutably demonstrated a more than controversial reality: the phenomenon of quantum entanglement – ​​where the quantum states of two particles are connected regardless of the distance between them. It is the basis for the development of current quantum computers and has made it possible to understand what Einstein called “spooky action at a distance”.

Until the late 19th century, it was believed that reality was accessible to us and that scientists were external observers of phenomena that they could then describe objectively. Quantum physics, working within the infinitesimally small, triggers a lively debate about science’s relationship to reality.

In fact, we can objectively know the world around us by measuring it. But the act of measuring in the quantum world therefore changes and perturbs the object under study. De facto, it is impossible to know its state before the measurement. Hence the question: are particles “things” in themselves, can we attribute to them an autonomous physical reality beyond observation? Einstein amused himself by saying: Do you really believe that the moon is not there when you are not looking at it? This is the basis of what is called quantum entanglement.

It should be known that quantum entanglement is the phenomenon where two particles (or more) exist in a so-called entangled state, that is, despite the distance that separates them, they behave as a whole: a modification of a of them leads to a change in the other.

Working independently, each of the three scientists awarded the 2022 Nobel Prize in Physics has created new experiments that demonstrate and study quantum entanglement. If an observer determines the state of such a particle, its entangled counterparts will instantly reflect that state, whether they are in the same room as the observer or in a galaxy on the other side of the universe! Their results established the violation of the so-called Bell inequalities and paved the way for new technologies based on quantum information, which are currently used to develop quantum computers, quantum cryptography and the future quantum internet.

Bell’s inequalities, a demonstration of quantum entanglement

First elucidated by Erwin Schrödinger in 1935, leading to his famous cat paradox, entanglement was dismissed by Albert Einstein as “spooky action at a distance” and sparked a long philosophical debate about the physical interpretation of quantum mechanics. Was it a complete theory or was it quantum entanglement due to “hidden variables” because its laws did not make sense in the macroscopic world.

In 1964, CERN (European Organization for Nuclear Research) theorist John Bell proposed a theorem known as Bell’s inequalities, which put this question to the test. Specifically, he explains that if hidden values ​​are at stake, the correlation between the results of a large number of measurements will never exceed a certain value; conversely, if quantum mechanics is complete and therefore a valid theory, this value can be exceeded. Indeed, this is what happens: all the experiments that have put these inequalities into practice, including those of the three Nobel laureates, show that they have been exceeded and that quantum physics is indeed a complete theory.

Specifically, John Clauser (JF Clauser & Associates, USA) was the first to experimentally study Bell’s theorem, obtaining measurements that clearly violated a Bell inequality, thus supporting quantum mechanics. Then Alain Aspect (Paris-Saclay University and École Polytechnique, France) put the results on firmer ground by envisioning ways to perform measurements of entangled photon pairs after they have left their source, thus eliminating the effects of the environment in which they were emitted . Finally, using refined tools and a wide range of experiments, Anton Zeilinger (University of Vienna, Austria) began using entangled quantum states to demonstrate, among other things, quantum teleportation, which allows a quantum state to be transferred from one particle to another.

As the CERN statement summarizes, these delicate and groundbreaking experiments not only confirmed quantum theory, but also laid the foundation for a new field of science and technology that has applications in computing, communication, detection and simulation.

The universe is not truly local, a fundamental principle of quantum computing

Currently, therefore, entanglement is accepted as one of the main features of quantum mechanics and is being implemented in cryptography, quantum computers and a future “quantum internet” to the tune of over $1 billion a year. One of his earliest successes in cryptography was sending messages using pairs of entangled photons, creating cryptographic keys in a secure way – any eavesdropping will destroy the entanglement and alert the recipient of the hack.

Thus, it would be an obvious illustration that the universe is not locally real, demonstrated by the Nobel-winning scientists this year. As explained in an article by Scientific American, “real” means that objects have defined properties independent of observation: an apple can be red even when no one is looking at it, which is not the case in the quantum world. The properties of objects are interdependent on observation.

“Local” means that objects can only be influenced by their surroundings, and any influence cannot travel faster than light. This is also not the case in quantum physics “because of” quantum entanglement. The trio of researchers have thus demonstrated that objects are not only affected by their surroundings, a modification of a particle will have consequences for its entangled particle, e.g. several light years away.

In 2017, Dr. Zeilinger used the technique via a Chinese satellite called Micius to have a 15-minute encrypted video chat with Jian-Wei Pan of the Chinese Academy of Sciences, one of his former students. The satellite, built in part thanks to John Clauser’s discoveries, uses several properties of quantum mechanics applied to photons, the elementary particles of light. The satellite is able to produce and emit pairs of entangled photons into two telescopes separated by 1203 kilometers.

Although he acknowledged that the award honors future applications of his work, Dr. Zeilinger in an interview with New York Times : ” My advice would be: do what you find interesting and don’t worry too much about possible uses Dr. Clauser, for his part, says: I still admit today that I still don’t understand quantum mechanics, and I’m not even sure I really know how to use it well. “.

However, in an article by Science newsNicolas Gisin, a physicist at the University of Geneva in Switzerland, emphasizes: This award is well deserved but comes a little late. The majority of this work has been carried out in [années 1970 et 1980]but the Nobel committee was very slow and is now urgent after the boom of quantum technologies “.

This boom is happening globally. Gisin concludes: In the US, Europe and China, billions – literally billions – of dollars are being poured into this area. So it changes completely. Instead of having a few pioneers in the field, we now have very large groups of physicists and engineers working together “.

Although some of the quantum applications are in their infancy, the experiments of Clauser, Aspect and Zeilinger introduce quantum mechanics and its implications to the macroscopic world. Their contribution validates some of the central, once controversial ideas of quantum mechanics, and promises new applications that may one day find their way into everyday life.

Leave a Comment