Wintertime

 First day of winter, but things feel odd. It is cold but there is no snow,

and we are headed for a green Christmas in the Montreal region. Still,

good to turn the corner on long nights.

Asked Bing Create for an image from Finland. Yo, wintertime...

                                                     

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source: Slate Fr

translation: GoogleTranslate/doxa-louise

How is the concept of quantum entanglement used?

Quora — February 4, 2023 at 9:58 a.m.

If the concept seems obscure, the phenomenon can have real applications, still studied by scientists.

Quantum entanglement has potential applications in areas of quantum information, such as quantum cryptography, quantum teleportation, or quantum computing.

Question of the day : “What is quantum entanglement used for?”

Jules Ruest 's (Montreal) response :

Excellent question, which is why I am happy to answer it by being as clear as possible in my explanations. First of all, before answering this question directly, I would like to explain what quantum entanglement is .

It must be said that this phenomenon defies belief. Quantum entanglement refers to the existence of an invisible link between two particles that were emitted at the same time, regardless of the distance separating them. In this way, if the state of one of them changes, that of its twin changes instantly, as if it were a single system.

“When we “touch” one of a pair of entangled objects, the second one flinches, despite the distance , ” summarizes Nicolas Gisin , Swiss physicist and professor of physics at the University of Geneva. This phenomenon has been verified many times in the laboratory since the 1970s. Don't ask me how it's possible, scientists themselves have been tearing their hair out for decades to explain this phenomenon .

For the moment, nothing is understood about this invisible link. But despite everything, understanding its mechanism, much research has been undertaken to exploit this fabulous property in the fields of quantum information, such as quantum cryptography, quantum teleportation and quantum computer .

Quantum cryptography

It exploits the principles of quantum entanglement to make a message incomprehensible to anyone who intercepts it, except the person for whom it is intended.

To the extent that it is impossible to clone entangled information without it being destroyed, or to measure a quantum state without modifying it, the reading of the information by an intruder would be immediately detected by the recipients of the message.

Quantum teleportation

It is not a question here of actually teleporting objects or people as in Star Trek , but rather of setting up a communication protocol consisting of transferring the quantum state of a system to another similar system spatially separated from the first by taking advantage of quantum entanglement.

Quantum computer

A quantum computer is the equivalent of a classical computer, except that its calculations are carried out at the atomic scale. It is based on the laws of quantum physics , which focuses on the behavior of matter and light at the microscopic level.

At this scale, strange, totally counterintuitive phenomena occur. An object can be in several states as long as it has not been measured: this is the principle of quantum superposition . And two objects can influence each other even when separated by a great distance: this is the principle of quantum entanglement.

Quantum entanglement is a fascinating area of ​​research that never ceases to amaze and for which new fields of research will certainly emerge in the future.

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