Chapter 1187

It's time to do something, too.

In order to control the last link of the task chain, there are a lot of things waiting for him to finish.

But just as he was about to get up from his desk, there was a knock on the door outside the office.

Thinking of the appointment on the phone yesterday, Lu Zhou guessed who it was, threw the tissue into the packing box, tied the plastic bag tightly to one side, cleared his throat and said.

"Come in, please."

The door of the office opened, only to see director Li's familiar and no surprise face appeared at the door, and to see the packing box beside the table, he was about to smile and say hello, his face could not help but show a surprised expression.

“…… Do you eat this at noon? "

The boat gave him a strange look.

"Two meat and one vegetable, any questions?"

"Er, no..."

"I don't want to talk about it. I will go back to the higher Research Institute for a meeting at 3:00 p.m. about the work of the moon orbit construction committee," continued Lu Zhou, looking at the time on his watch. "What did you tell me on the phone yesterday?"

Director Li didn't speak. He took a look at Wang Peng.

Wang Peng nodded, picked up the packing box and walked out of the office.

There are only two people left in the office.

Seeing no one else, director Li said.

"It's about that quantum encryption algorithm."

Hearing this, Lu Zhou's eyebrows immediately raised with interest.

"Is it easy to use?"

"Easy to use! It's so easy to use. " Director Li clapped his hands and said with a smile, "you don't know, the deputy director of the Institute of information engineering of the Chinese Academy of Sciences almost didn't knock his chin on the ground when he saw it..."

There is always a bad feeling about the land boat when I see this guy's face dancing.

Every time the old man and he are courteous, either he is going to introduce him or he has something to trouble him.

“…… Since it's easy to use, what are you looking for me for? "

Director Li said with a smile.

"Some time ago, you said that after your carbon based topology quantum processor chip came out, it will not be long before the quantum computer can break through 1000 qubits?"

The boat thought for a moment and nodded.

"I do seem to have said that."

"For this matter!" After clapping his palm, director Li continued, "the Ministry held a meeting a few days ago to discuss this issue. However, we really lack experts in this field. After a long discussion, we couldn't come up with a conclusion..."

"Stop, don't explain the cause and effect to me," Lu Zhou raised his hand, stopped director Li, sighed and said, " Just tell me what's the trouble. "

"It's not a problem, but it's mainly to ask for your advice," said director Li with a embarrassed smile When will this 2000 qubit computer come out? "

Upon hearing director Li's words, Lu Zhou immediately understood what he was thinking and worried about the timeliness of technology for a long time.

But it's also hard to avoid. Generally, individuals have such concerns.

If the bottleneck from 80 to 500 is so easy to break, it's hard to say how long the technical barriers from 500 to 1000 and from 1000 to 2000 can last.

Changing the encryption algorithm is not a trivial matter like changing a penguin password. It involves the reform of the whole communication field. The hidden social cost that needs to be paid is difficult to be measured by money alone.

If possible, the relevant departments naturally hope to change the encryption algorithm once, which can be managed for a little longer.

Don't update the encryption algorithm in three or five years. Even if China's financial industry, communication industry and Internet industry can't stand such a toss

"It's not unreasonable for you to worry about it," said the boat, after a moment's deliberation, with a slight tapping of the index finger on the table, "but it's really hard to say. I can only tell you that the bottleneck of 1000 qubits can be broken in a short time, but 2000 qubits I can't give you an accurate estimate until at least 1000 qubits have broken through. "

Director Li said, "I don't think it's all right."

"It's not a question of whether it's OK or not, but it's meaningless at all," sighed Lu. "If you just want to seek psychological comfort, it's better to find a fortune teller. From the perspective of probability, it's all five to five. And... "

After a pause, the boat continued.

"The quantum encryption algorithm is always a one-time one. N qubits correspond to 2 ^ N states, not 2 times n. In theory, if it is only the difficulty of linear heap high proposition, one day our encryption means will not be able to catch up with the development speed of our information technology. "There was silence in the office.

Chewing on the words of land boat repeatedly, director Li pondered for a long time, and asked after a long time.

"What do you think we should do?"

"We can only fundamentally solve this problem," Lu said after thinking for a while. "That is to say, we can eliminate the possibility of leaks by means of communication!"

"You mean Quantum communication? "

The boat nodded approvingly.

"Exactly."

Director Li's expression was dignified.

“…… But I heard that quantum communication technology is not simple, is it? Our country is still ahead of other countries in this area, and there are many achievements, but I haven't seen the trend of this technology to mature. "

"It's normal that we don't see this trend," Lu said, "because the breakthroughs in this field are mainly focused on the realization of photon entanglement and the enhancement of signal strength, but the key to the real realization of quantum communication is the quantum repeater."

Further more, quantum repeater can be divided into two propositions: "quantum memory" and "efficiency of writing and reading quantum states and optimization of storage time".

These two technical difficulties are mentioned in dlcz scheme. The combination of quantum memory and single photon channel is used to suppress the attenuation and realize long-distance quantum communication.

However, because there is little progress in quantum memory, quantum communication can only be realized within 100 kilometers, and the transmission environment is extremely demanding. And this also lost the practical value, and even was once doubted whether it could be realized.

"Quantum repeater?"

"Well," Lu Zhou nodded, looking at the thoughtful director Li, "it's not that there is no progress, but that there is no progress at all. This is the same all over the world... "

The reason why quantum communication can be absolutely confidential is because of the special characteristics of wave function. Once the photon transmitting information is intercepted, any observation behavior will lead to the collapse of entangled state.

To put it plainly, call between a and B. if there is a third party, C, standing in the middle, eavesdropping. No matter what method C adopts, use a bug or stick the ear on the wall, as long as C hears a word, a and B can immediately know that the communication is bugged, and the whole information will lose its meaning.

Including asymmetric encryption algorithm, all encryption algorithms are aimed at traditional means of communication. In the face of quantum communication technology, encryption is unnecessary.

This is also called "unconditional security"!

In about five minutes, Lu Zhou gave director Li a brief introduction to the technical difficulties of quantum communication and its advantages over traditional means of communication.

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 from academician Lu's mouth, and the meaning of the moment was different.

After listening to the explanation of Lu Zhou, his heart was burning and he asked quickly.

"Is this unconditionally secure quantum communication difficult?"

The boat looked serious.

"To be honest, it's not just hard! It's quite difficult! "

"Aside from what I said you didn't understand, all you need to know is that this is basically the most core bottleneck limiting the commercialization of quantum communication technology."

The office is quiet again.

This time the quiet time is a little long.

Lu Zhou took a drink from the water glass on the table, moistened the mulberry seed, prepared to comfort the old friend and told him not to worry too much. That encryption algorithm can be used first. When the 2000 qubit computer comes out, it's not sure that the research of quantum repeater has made new progress.

The birth of any new technology will take time to precipitate. Although the quantum encryption algorithm he developed is not particularly brilliant in his own eyes, there is no problem in dealing with it for a while.

However, just as he was about to speak, director Li took the lead.

“…… Well, that quantum repeater, can you handle it? "

Lu Zhou: "......"