This article comes from: “SELF Lattice Forum” public number (ID: SELFtalks)
The following is from the speech of Luo Huizhen, an associate researcher at the Institute of Physics, Chinese Academy of Sciences:
The topic I am talking about today is quantum. I brought three sets of “toys”, all of which have the same principle.
Let ’s do our first experiment first. This is a circular orbit. This is a block material. We put a block of material in liquid nitrogen and soak it, then put it on the track. Look, what happened? That’s right, it was suspended in orbit. I push it, and it can move around the track.
Let’s do another experiment. This is a magnet, this is a ring-shaped object. On the surface, this ring-shaped object is nothing special, in fact, it contains a superconducting coil inside. Normally, we cannot use this ring to hold the magnet without touching the magnet. But this can be done with the help of liquid nitrogen.
We bubble this ring with liquid nitrogen and let it cool down. Okay, everyone sees that the magnet has now been held up and it is completely suspended. We need a lot of force to pull it down. This is actually the quantum effect. Quantum experiments are easy to do in real life, but students should not play with this magnet at home, because it has a very strong suction force, and it will pinch your hands by accident.
Please
Okay, that’s it for experiments. The topic I want to share today is “quantum love.” Everyone is a junior high school student and can’t fall in love yet. But quantum love is not the same. Let ’s talk about what is quantum love and how it is in love.
Electronic arrangement
When it comes to quantum, how can we find it? In fact, as long as your eyes are powerful enough, you can find atoms. After peeling the atoms apart, there are positively charged nuclei and negatively charged electrons. The electrons revolve around the nucleus, but the trajectory of the electrons is not as regular as that of the planets. The electrons randomly rotate.
Atoms have electrons, and electrons are a quantum, and the nucleus is also composed of many quantum. We often say that electrons are quantum, so if you can manipulate electrons, you can manipulate many quantum phenomena.
Why are electrons quantum? Not only is the electron negatively charged, it is also like a small magnetic needle. There are many magnetic phenomena in life because electrons can be arranged in order. Electrons are arranged in two states: one facing up and one facing down. This is called spin in physics. You don’t know if it’s facing up or down, the arrangement is very random.
Many people think that electrons look like balls. In fact, particles do n’t look like balls. They only have hydrogen atoms. The shapes of the particles are messy, dumbbell-shaped, plum-shaped, etc . If you put these electrons in the same atom, do you know what form they will be arranged in? Will be arranged in a cube.
What materials in life are cubic structures? Yes, salt. How does an electron move in an ordered atom? That’s right, the electron can’t move at this moment, because it will encounter various obstacles, which is what we often call resistance. Let’s make a metaphor of the image: the electronic runs on the highway, it encounters various “toll stations”, the electronic will stop to pay, the energy will be lost, and the speed of the movement will be slower. So, electronic movement Obtained certain resistance, this is called resistance.
It seems that any conductor has a resistance. Is there any way to remove the resistance? Just now we used liquid nitrogen in our experiments. The main role of liquid nitrogen is to cool the conductor. In fact, scientists have also made many related guesses. The following are three representative guesses.
The first guess was made by Kelvin. He believes that after the temperature drops, the electrons will be frozen and the resistance will rise. This guess sounds reasonable. Second guess is horseHeyson made it. He believes that the resistance will decrease as the temperature decreases, but some of the resistance cannot be avoided and will always exist. Even at absolute zero, the resistance still exists. The third guess was made by Dewar. He believes that if a perfect material is found, the resistance of the material will be zero at absolute zero.
Later, these three guesses were found to be incorrect. The superconducting material used in the experiment just now proved that After a certain temperature, the resistance will drop to zero and the resistance will disappear. The phenomenon of resistance disappearing is also called superconducting phenomenon.
The superconducting phenomenon was discovered by physicist Camerin Ones. The first superconducting material to be discovered was metallic mercury. At that time, Carmelin Ones reduced the temperature of mercury to 4.2K. / span>, and measured its resistance dropped to almost zero.
What is the concept of zero resistance? If you know electromagnetic induction, you can create a circuit circle, and then add a magnetic field to measure the corresponding induced current. You can observe the change of the magnetic field by measuring the change of the induced current.
If you do this experiment in a superconductor, if you add one amp of current, you guess how long the current will decay to zero?
About 100 billion years. Older than the universe. This is the magical superconducting phenomenon, and it can last so long. That is, it can transmit power almost without loss. Why is the resistance zero? Let us return to the original theme-quantum love.
A negatively charged electron moves among positively charged atoms, and it will attract a group of positively charged atoms. Because the masses of electrons and atoms are very different, when they attract atoms, they leave quickly. At this time, another electron comes, and the group of atoms will release energy to the second electron again.
In this way, these two electrons that have nothing to do with each other virtually have an interaction, forming a so-called Cooper electron pair, they are no longer alone, they are “in love”, This is the love we are going to talk about today.
I liken this love to “love on the edge of the lace” because the electrons are feminine. It is a bit like two girls have a love relationship after being introduced by a group of boys.
Actually, there are many electrons in a material, not just two. These electrons are very far apart. What happens if a group of these electrons are paired?
That would create huge quantum waves across the entire range of materials. At ultra-low temperatures, these paired electrons have equal and opposite momentums, so they can move in the atom unhindered, so there is no resistance.
If it is difficult for everyone to understand, I can make another figurative metaphor. An electron is like a defective bee. It has only one wing, some have only left wings, and some have only right wings. Defective bees cannot fly by themselves and must fly in pairs.
Also, you ca n’t fly in random. To fly in one direction, you must be an electron pair. The distance between electron pairs can be very, very long, but as long as one is moving, the other will follow.
Atoms are arranged in order, and electrons are also arranged in order. They are just like soldiers on the parade ground. A group of soldiers came over and another group of soldiers came over again. What should we do when we meet on a narrow road? You can only fight in groups.
If we put two superconductors together and separate them with an insulator in the middle, the electrons in the left superconductor and the right superconductor do not know each other, but they are all united. Generate two light waves, this is called double slit interference. Two groups of electrons also interfere, which is called Fraunhofer diffraction.
We can see that the electrons are distributed in space strongly and weakly, and are adjustable. We only need to change the magnetic field a little to change its shape. In this way, we can construct very sensitive quantum detection Device.
Electrons make a circle around Josephson, which can be wound forward or reverse, so that the magnetic field will come up, one down, and this is the superposition state of two quantum.
The quantum computer came into being
Don’t underestimate the knowledge I just talked about, that is actually the basic principle of quantum computers. This photo was taken of a quantum computer.
If quantum entanglement is constructed, quantum calculations can be done. Quantum computing is very powerful and very fast. Do you know how fast it is?
It may take 10,000 years to do a certain calculation with a computer cluster as large as a building, but it only takes one second to perform calculations with a quantum computer!
However, quantum computers, while good, are very difficult to build. It’s like it’s easy to put two superconductors together, but it’s very difficult to put countless superconductors together.
This is a 20 quantum ratio made by Chinese scientistsSpecial chips, with quantum chips, you can do quantum computing.
Not long ago Google announced the development of a quantum processor consisting of more than 50 qubits. You may not realize what this concept is.
In the future, if a 50-bit quantum computer can be built, it will surpass all the computers now, and all computers now are scum in front of it. It will crack all passwords in an instant, and it will be very scary. Everyone imagine what the world would look like if such a quantum computer really existed in the future.
What’s more terrible is that this quantum computer is not artificial, but created by AI, so many people worry that the future will be the era when robots rule humans. Of course, it is very difficult to build such a quantum computer. The electronic computer just mentioned actually lasts a very short time, and the state can easily be destroyed. So we need to look for a more complex quantum state.
Many people do n’t know the scientist in the photo. He is a Soviet scientist named Pogoryupov. We often laugh and say that he is a special hiccup.
What do you mean? As mentioned earlier, to form a superconducting effect, electrons must be paired. But if you add a magnetic field and temperature to a pair of electrons that are in love, you can give themopen.
The two scattered electrons will not be divided into two electrons, but will be divided into two different particles. Such particles are called Pogoryupov particles.
Pogoryupov particles are divided into a pair of fermions, Mayorana fermions.
Majolana is a mysterious physicist who has been silent since he left home in his twenties. The mysterious Mayorana was born with advanced physical thinking, and he predicted that a particle’s antiparticle is itself. It turned out that this particle was real, so it was called Mayorana Fermion.
We think this kind of particle is like the “coexistence of angel and devil”. It is very difficult to manipulate something that is both angel and devil. We need a very unique material. This material is first a superconductor. Make a layer of topological insulator and combine the two to produce the mysterious Mayorana Fermion.
With the Mayorana Fermion, the quantum chip is different. It is protected by topology and can obtain a very stable quantum state. The quantum state will always exist as long as it is not forcibly destroyed. Topological quantum computing can also guarantee the accuracy of calculations and achieve the requirements of high-precision operations.
The future of quantum research
If futureIf quantum devices are really realized, we will usher in a brand new quantum world. Don’t think that the quantum world is far away from us, in fact it is very close to us.
Google has built a quantum computer, and people can also experience quantum computing through a quantum simulator. China proposed the quantum plan a few years ago, and plans to build a quantum computer in China within ten years. Two or three years have passed now, and China’s quantum technology development has made tremendous progress. Let’s recall that when the first computer was built, it was as high as three floors and as large as a building.
But now, any phone in our hands is much more powerful than the first computer at the time. This rapid change took only two or three decades.
Now it seems that scientists are studying quantum computing. Perhaps ten years later, our mobile phones and computers will be quantized. At that time, a quantum cell phone will be equivalent to a supercomputer now.
The realization of everything in the future depends on the beginning: The love generated by a group of electrons in the quantum world of materials gives us the opportunity to manipulate it artificially, and to build the future quantum world.
This article comesFrom: SELF Talks Public Forum (SELFtalks)