Chapter 1187: Unconditional security

It's time to get drunk and do something.
In order to control the last link of the task chain, there is a basket of things waiting for him to complete.
However, just as he was about to get up from his desk, there was a knock outside the office.
Thinking of the appointment on the phone yesterday, Lu Zhou probably guessed who it was. He threw the paper towel into the packing box, and tied the plastic bag aside, and cleared his throat and said.
"Come in."
The door of the office opened, and I saw Director Li's familiar and unsurprising face appearing at the door. When he saw the packing box resting near the table, he was about to greet him with a smile and his face was exposed. Surprised expression.
"... You eat this at noon?"
Lu Zhou gave him a strange look.
"Two princes and one prime, is there a problem?"
"Uh, no ..."
"If you do n’t, let ’s just talk about it. I will return to the Institute of Higher Education for a meeting more than three in the afternoon about the work of the Lunar Orbital Construction Committee. He continued, "What the did you tell me on the phone yesterday?"
Director Li did not speak, and looked at Wang Peng.
Wang Peng nodded, and thoughtfully picked up the packing box to exit the office, and brought it to the door.
There are only two people left in the office.
Seeing no one else, Director Li said.
"It's about that quantum encryption algorithm."
As soon as he heard about it, Lu Zhou's eyebrows raised with interest and asked.
"is it useful?"
"Easy to use! It's so easy to use." Director Li patted his hands and said with a smile, "You don't know, our Deputy Director of the Institute of Information Engineering of the Chinese Academy of Sciences almost surprised me after seeing My chin is on the ground ... "
Seeing this guy's eyebrows flickering, Lu Zhou always had a bad feeling.
Every time the old man and him dedicated, he either intended to introduce him to the object or troubled him if something happened.
"... Since it works, what are you doing to me?"
Director Li said with a smile.
"Do n’t you say that after your carbon-based topological quantum processor chip came out, it won't be long before the quantum computer can break through 1000 qubits?"
Lu Zhou thought for a while and nodded.
"I wish I had said it."
"That's what it is!" After taking the palm of his hand, Director Li continued, "A few days ago, a meeting was held in the ministry to discuss this issue, but we really lack experts in this area, and we can't discuss it for a long time. That's why ... "
"Stop it, you don't need to explain the cause and effect to me," Lu Zhou raised his hand, stopped Director Li's words, and sighed, "... tell me what's wrong with you directly."
"It's not too much trouble, mainly because I want to ask for your opinion," Director Li smiled embarrassedly, and asked, "... when will this 2000-qubit computer come out?"
Upon hearing Director Li's words, Lu Zhou immediately understood what he was thinking, and he was worried about the timeliness of technology for a long time.
However, it is inevitable that such concerns are generally personal.
If the bottlenecks from 80 to 500 are so easy to break, it is difficult to say how long the technical barriers from 500 to 1000 and from 1000 to 2000 can persist.
Changing the encryption algorithm is not a trivial matter of changing the penguin password. This involves the reform of the entire communications field. The hidden social costs that need to be paid cannot be measured simply by money.
If possible, the relevant departments naturally want to change the encryption algorithm once, and can manage it for a little longer.
Do n’t update the encryption algorithm every three to five years. Even if China ’s financial industry, communication industry, and Internet industry are so tough, they wo n’t be able to stand up to it ...
"It's not unreasonable to worry about you," said Forefinger tapping gently on the table, and Lu Zhou thought for a moment, and said, "But this thing is really hard to say. I can only tell you that the bottleneck of 1000 qubits is It can be broken in a short time, but 2000 qubits ... I have to wait for at least 1000 qubits to break through before I can give you an accurate estimate. "
Did Director Li "probably not work at all?"
"It's not a question of estimating but it's not meaningful at all," Lu Zhou sighed. "If you just want a psychological consolation, you might as well ask a fortune teller. From the perspective of probability, it's all 50 or 50." ... "
After a pause, Lu Zhou continued.
"Quantum encryption algorithms are always temporary, and n qubits correspond to 2n states, not 2 times n. In theory, if it is only a linear difficulty of proposing propositions, one day our encryption methods will not be able to recover At the speed of our information technology development. "
There was silence in the office.
Chewing on the landing boat repeatedly, Director Li pondered for a long time, and then asked him seriously after a while.
"Then what do you think we should do?"
"This problem can only be solved fundamentally," Lu Zhou said after thinking for a while, "that is to say, the possibility of leaking through communication means is avoided!"
"Do you mean ... quantum communication?"
Lu Zhou nodded approvingly.
"Exactly."
Director Li's expression was dignified.
"... But I heard that quantum communication technology is not simple, isn't it? Our country is still relatively advanced in this area, and there are many achievements, but I have never seen a sign that this technology is becoming mature."
"It is normal to see this sign," Lu Zhou said, "because breakthroughs in this field are mainly focused on achieving photon entanglement and enhancing signal strength, but the key to realizing quantum communication lies in quantum repeaters. on."
If you subdivide further, the quantum repeater can also be subdivided into two propositions: "quantum memory" and "optimization of the efficiency and storage time of writing and reading of quantum states".
The two major technical difficulties are mentioned in the dlcz scheme. The combination of quantum memory and single photon channel is used to suppress attenuation to achieve long-distance quantum communication.
However, due to the lack of major advances in quantum memory, quantum communication can only be implemented at distances of less than 100 kilometers, and the transmission environment is extremely demanding. And this also loses the practical value, and even once was suspected that it is impossible to achieve.
"Quantum repeater?"
"Well," looking at the thoughtful Director Li, Lu Zhou nodded. "This is not no progress, but no progress at all. This is the same all over the world ..."
The reason why quantum communication can be kept absolutely secret is because of the special characteristics of the wave function. Once the photons transmitting information are intercepted, any observation behavior will cause the entanglement state to collapse.
To put it plainly, call between a and b, if a third person c stands in the middle and taps. Regardless of the method used by c, using an eavesdropper or sticking his ears to the wall, as long as c hears a word, a and b will immediately know that the communication was eavesdropped, and the entire message will lose its meaning.
Including asymmetric encryption algorithms, all encryption algorithms are targeted at traditional communication methods. In front of quantum communication technology, encryption is simply superfluous.
This is also called "unconditional security"!
After spending about five minutes, Lu Zhou briefly explained the technical difficulties of quantum communication and its advantages over traditional communication methods to Director Li.
Although they are all old-fashioned things, Director Li has heard many people talk about similar things with him before, but this time after all, it was told from Academician Lu's mouth, and the meaning is different.
After listening to Lu Zhou's explanation, his heart suddenly felt hot, and he asked quickly.
"Is this" unconditionally secure "quantum communication difficult?"
Lu Zhou nodded seriously.
"To be honest, it's not just difficult! It's quite difficult!"
"Let ’s put aside the parts that I do n’t understand ~ EbookFREE.me ~ You just need to know that this stuff is basically the most important bottleneck that limits the commercialization of quantum communication technology.
The office was quiet again.
It's been a little longer this time.
Lu Zhou took a sip from the water glass on the table, moistened Run Sangzi, prepared to comfort the old friend, and told him not to worry too much. That encryption algorithm can be used first, until the 2000 qubit computer comes out, maybe the research on quantum repeaters has also made new progress.
The birth of any new technology requires time to settle. Although the quantum encryption algorithm he developed is not considered to be particularly clever in his own opinion, it will be fine for a while.
However, just when he was about to speak, Director Li could not help but take the first step, and the monkey with an expression on his face hurriedly asked.
"... So, that quantum repeater, can you handle it?"
Lu Zhou "……………………"
.