Quantum Entanglement really won the Nobel Prize this year! Is this theory worthy of awards?
Quantum entanglement is the core of in 2022 Nobel Prize in Physics. It is obtained because of measurements that Einstein believes are impossible to make, and the understanding we gained from these experiments is crucial to today's quantum computing , so what is the importance of this work? What did they prove? Is this theory worthy of awards?
First, let's discuss the emergence of quantum mechanics . Before the advent of quantum mechanics, we thought the world was deterministic, that is, if we knew enough information about the system in advance, then in principle we could decide everything about the system in the future. Unfortunately for determinists, we ended up encountering quantum mechanics, which runs contrary to determinism.
In terms of its essence, probability theory was not applicable to many scientists, including Einstein at the time. Proving that quantum mechanics has this property is an important part of the early Nobel Prize in quantum mechanics in 2022. Before this, scientists discovered and proposed many theories, but there was an idea that the mechanical framework of quantum mechanics was just a copy of reality. Despite very good predictions, there was still a more basic theory to explain everything, so the current framework could well predict ridiculous results, so Einstein firmly believed that in order to prove this, mechanics was indeed incomplete.
In 1935, Einstein and two other authors published a paper titled "Can the Quantum Mechanical Description of Physical Reality be considered complete." They outline a thought experiment, called the Einstein-Podosky-Rossen paradox or the EPR paradox for short. The thought experiment must be related to quantum , and entanglement - is a state of correlation between two quantum systems. Suppose you have two electrons spin , which can be spin up or spin down. The entanglement of these two electrons will produce an interesting state. If one of the electrons is measured to spin up, the other must be spin down, which is the result of the respective properties of the quantum object.
electrons can be described as wave function , that is, when you measure the wave function, the wave function of each particle is different. When two particles are entangled together, through measurement, we will destroy the wave function. If you measure one of the electrons, the functions of these two particles will collapse. This is the key to thought experiments. If you separate the two entangled particles and then separate them far away, we can say that they are separated by several light seconds in this state. If you can measure one of the electron states, for example, when the spin rises, the other electron will immediately become spin-descending. Einstein called this wave function collapse "ghost action distance" and pointed out that there must be some hidden variables that can know their state in advance, so no information propagates faster than the speed of light.
Einstein believes that after the particles separate before they form, they decide which one will become spin up and which one will become spin down. For many years, humans have no way to distinguish between Einstein's theory of hidden variables and standard quantum mechanical entanglement. It was not until 1964 that John Bell proposed that there is indeed a way to test whether the hidden variable is true. This test will be called Bell inequality . This test is by measuring an quantum state , i.e. how we choose how to measure it, it all depends on how you measure them.
John Bell said that in this scenario, you measure an electron, see if it is up or down, and then measure the second electron at an angle between the Z and X directions of the coordinate axis, and finally you will find that there is a difference in the results between the hidden variable and quantum mechanics.
This year, three people won the 2022 Nobel Prize in Physics, John Crowther, Alan Aspek and Anton Zellinger , who were awarded the Entangled Photon Experiment, demonstrating violations of Bell's inequality, and conducting pioneer tests of Bell's proposed experiments. In fact, quantum information science is actually quite difficult and requires very fast and very precise measurements. At that time, quantum computing was not as popular as it is now. In fact, it was the same as it did not exist at that time, so no one was really interested in proving that Bell's theory is difficult after all, and there is no reward.
But despite this, John Crowze conducted this experiment in 1972 and the results showed that quantum mechanics is indeed effective and there are no hidden variables. Then in 1982, Allen's side conducted a more rigorous Bell test, which made up for some people's belief that allowing hidden variables is still correct, two main experiments won the Nobel Prize, and then in the 1990s, Anton Zellinger measured the entangled state to prove the so-called quantum stealth transport. Basically, if you take two entangled electrons, one interacting with the third electron, the entangled state can be transferred. This concept is crucial for any form of quantum communication, and because of this, it is crucial for many quantum communication studies conducted today.
Anton Zellinger demonstrated quantum teleportation in the laboratory and within a few hundred kilometers of recent distances. All three scientists conducted groundbreaking research, paving the way for the second quantum revolution, so they all deserved the Nobel Prize.
