The Nobel Prize in Physics was awarded on Tuesday to the Frenchman Alain Aspect, the American John Clauser and the Austrian Anton Zeilinger, for their work on the mechanisms of quantum physics.
More specifically, the trio of physicists were rewarded for their discoveries of “quantum entanglement,” a phenomenon in which two quantum particles are perfectly correlated, regardless of the distance between them.
To explain this phenomenon, Chris Phillips, a physicist at Imperial College London, takes the example of a photon, a particle of light. Passing it through a special crystal, two photons come out.
“They don’t have the same color as the original, but since they come from the same photon, they get entangled,” he told AFP.
The two entangled particles behave identically, as if they were connected by an invisible thread. The measure of the properties that we make on one, when examining it, instantly affects the other, whatever the distance that separates them.
Discovered 40 years ago
A photon is a quantum, a definite amount of electromagnetic energy. Alain Aspect discovered in 1982 that two photons can behave as a single quantum system, even if they are at a distance.
This breakthrough “opened the way to the field of new quantum technologies, which today are revolutionizing information processing and communication,” according to the CNRS. The application of this discovery to computers, to create powerful tools, is not yet close, Alain Aspect said during a press conference on Tuesday.
Even Albert Einstein, one of the founders of quantum theory, did not believe in it, believing that such instantaneity was not possible.
“I like to say that Einstein has great credit for raising the question” of nonlocality, one of the foundations of entanglement, Alain Aspect said Tuesday.
His co-laureates of the Nobel Prize in physics, the Austrian Anton Zeilinger and the American John Clauser, have also tested this theory, called Bell’s theorem, and ruled out any explanation other than non-locality. His work paved the way for what is known as the “second quantum revolution”.
The discoveries of Zeilinger, nicknamed “the pope of quantum”, showed the potential application of entanglement in encrypted communications, quantum teleportation, etc.
Chris Phillips, meanwhile, has developed an instrument, the size of a high-fidelity stereo, that uses quantum entanglement to diagnose breast cancers.
A particle in several states at the same time.
Quantum physics was born at the beginning of the 20th century. Some physicists then realize that classical physics, which “perfectly describes our everyday macroscopic environment”, becomes “ineffective at the microscopic scale of atoms and particles”, explains the Atomic Energy and Alternative Energies Commission on its website (CEA), a public research body. organization.
Quantum physics is thus a physical theory that deals with the behavior of physical objects at the microscopic level (atom, nucleus, particles).
Quantum physics is based on the idea that certain variations in magnitude are not continuous, but correspond to multiples of a minimum quantity. This minimum quantity is called the quantum.
Schrodinger’s cat
The CEA also explains that, unlike classical physics, quantum mechanics confuses corpuscles (atoms, particles) and waves (light, electricity): an electron, a molecule or an atom is both a wave and a corpuscle. According to the quantum superposition principle, a particle can be in several states at the same time.
This is what the physicist Erwin Schrödinger wanted to explain with his image of the cat in 1935. He imagined a cat locked in a box with a vial of poison that opens when a radioactive atom disintegrates. As in quantum physics the atom can be in two states, disintegrated or not disintegrated, we cannot know if the cat is alive or dead. Thus, the cat is in two overlapping states: dead and alive.
In classical physics, it appears that the cat is dead or alive. Schrödinger’s cat thus illustrates the difficulty of reconciling quantum physics and classical physics.
Source: BFM TV
