What is quantum entanglement What is the principle of Zhihu

The principle of quantum entanglement is actually a "superposition" property of quantum itself! We all know that today, after the baptism of classical mechanics and relativity, the human physics community has gradually entered the stage of "quantum mechanics", and we may be able to apply quantum technology to all aspects of life in the near future!

In the 21st century, the cutting-edge scientific and technological fields of all countries in the world have taken quantum mechanics as the biggest goal, such as the birth of emerging technologies such as quantum communication and quantum spacecraft!

As many people know, quantum can be described as one of the most mysterious substances in physics, and the mysteries behind it are simply countless! For example, the phenomenon of "quantum entanglement" makes many people puzzled! It stands to reason that within the framework of classical mechanics, it is impossible to "entangle" this state!

That's right, the so-called "quantum entanglement" only applies to our understanding of science through the lens of quantum mechanics! We all know that quantum mechanics has a famous "Schrödinger's cat" theory, which was originally used by physicist Schrödinger in the last century to refute the "Copenhagen interpretation" of Bohr and others;

As a result, the reverse has really become the golden rule that underpins the Copenhagen interpretation, that is, modern quantum theory! The story behind this "Schrödinger's cat" must be clear to everyone, that is, putting a cat in a box full of radioactive materials, and the switch is turned on from time to time;

Before we open the box and see the state of the cat, then in the quantum system, the cat is "dead and alive"! This "both dead and alive" is a phenomenon that shows that quantum is entangled in a superimposed state!

When humans are not observing, the "isolation" of the quantum itself may gradually combine, making the quantum "holistic"! Only after we saw the quantum changes in person did its existence "collapse" in an instant.

This is the mystery and principle of quantum entanglement!

What exactly is quantum entanglement? It turned out to be the culprit.

No one knows how it works, Einstein can't explain it, Hawking can't explain it, maybe someone will be able to explain it in the future.

The explanation is the phenomenon of quantum entanglement, it is just a statement, and the principle is not explained. The topic is a principle, not a phenomenon.

Popular examples of quantum entanglement are as follows:

There are two classic cases here, one is a widow model and the other is a glove model.

1) The widow model. Tie Dan and Cuihua were originally a couple, but after 10 years of long-distance love, they finally got married. At the moment of marriage, Tie Dan and Cuihua became husband and wife. This relationship is equivalent to the fact that two entangled particles share a common superposition state.

Suddenly, one day, the iron egg who was her husband hung up because of a car accident. So in fact, whether Cuihua wants to or not, at the same time that the iron egg hangs, it is also the same time that she becomes a widow.

This is equivalent to a measurement of one entangled particle, which affects another entangled particle at the same time.

2) Glove model, put a pair of gloves into two boxes at random, only when you open one of the boxes, you will also know what kind of gloves are in the other box.

These two cases are typical logical judgments, and this explanation can also make many people happily accept quantum entanglement.

But the problem is that this is not the case.

If quantum entanglement is a logical judgment, once it is measured, the result is certain and will not be changed.

In fact, if you open the box and find that it is a left glove, after closing the box and opening it again, it may become a right hand glove again.

Quantum entanglement is like this, where entangled particles are measured multiple times with different results.

This is strange, in order to explain this problem, Einstein also racked his brains, because in Einstein's view, any interaction between two particles must rely on a medium, but no medium can exceed the speed of light.