At 1:40 pm on August 16, Beijing time, the "Mozi" satellite developed by the National Space Science Center of the Chinese Academy of Sciences was successfully launched into the scheduled orbit at the Jiuquan Satellite Launch Center in China. The "Mozi" is a quantum satellite and the world's first quantum satellite.

This information directly smashed the circle of friends, everyone is celebrating, and China has one more world first.

The virtual reality circle is also brushing to celebrate the successful launch of the Mozi, and predicts that the future of quantum communication may change the development of virtual reality and greatly promote the progress of virtual reality.

But unfortunately, the VR Daily may have to pour cold water on everyone today: The Mozi flying is a happy event worth celebrating in the whole country, but quantum communication has little effect on solving the transmission bottleneck of virtual reality.

Quantum communication does not help increase channel capacity

Of course, it is not that the Mozi number is a vain name.

What is quantum communication?

According to the basic principle of quantum science: after two entangled photons are disassembled, no matter how far apart, there will always be telepathy, one shape will change, and the other will change synchronously like a mirror. The process of realizing optical quantum communication by using this characteristic is as follows: a pair of particles with entangled states are constructed in advance, and two particles are respectively placed on the communication sides, and the particles having the unknown quantum state are jointly measured with the particles of the sender (an operation) Then, the particle of the receiver changes instantaneously to a state that is symmetric with the state of the sender's particle change, and then the joint measurement information is transmitted to the receiver through the classical channel, and the received information is received according to the received information. By reversing the collapsed particles, you can get the same unknown quantum state as the sender.

Compared with classic communication, the security of quantum communication is almost absolute - never "disclosure."

In the process of quantum communication, the information itself is transmitted through classical communication, and the quantum communication transmits only the key. The key of quantum encryption is random, and it can be changed almost once. Even if the content itself is intercepted by the thief, the information cannot be cracked because the correct key cannot be obtained. If the stealer tries to intercept the key, it must first intercept the photon and then observe it. According to quantum theory, any observation and interference in the macro will immediately change the quantum state and cause it to collapse, so the photon will change. As a result, the key receiver either does not receive the photon or receives the photon and then checks with the sender. The result is not the same, and the communication process is monitored immediately. Of course, this does not matter. Once the key is found to be lost, apply for retransmission of the new key and confirm that the information is decrypted without error.

What is the role of the Mozi number?

In the field of wired fiber-based quantum communication, due to the indivisible nature of optical quantum, long-distance transmission can not perform signal amplification, but the loss is much, resulting in low information transmission efficiency at a long distance. The vacuum environment of space can greatly reduce the loss of light quantum in the transmission process. The distance between the ink number and the ground transmitting station is 500 kilometers, which can perfectly serve as a relay station for the quantum communication network covering the whole world. In this way, quantum communication is no longer limited to intra-domain communication, but can cover the entire planet!

Therefore, whether it is the Mozi number or quantum communication, the focus is not on channel capacity but on channel security. This has no connection with the large-capacity channel required by virtual reality, and it does not actually help the large amount of data transmission required by virtual reality.

The advantage of quantum communication is not speed, but confidentiality. The speed of information transmission in the classical communication mode is already the speed of light. Compared with the 4G network, the 5G network increases the number of transmission bytes per unit time, that is, the channel capacity. In this respect, the classic communication is much stronger than the quantum communication.

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