After coming out of the laboratory, Lu Zhou motioned to Academician Xue to wait for a while, then looked at the two security guards standing at the door, and instructed in a serious tone.

"Adjust the secrecy level here to Class A, and no one is allowed to approach here unless it is me."

The two security guards stood still and raised their hands cleanly in a military salute.

"Yes."

After leaving the Semiconductor Research Institute, Academician Xue looked at Lu Zhou, who was walking beside him, and asked.

"They're from the troops?"

Lu Zhou: "For those who have retired from the army and changed jobs, I have a good relationship with their regiment leader, so I will help arrange work." ”

If he comes out of the army, at least he doesn't have to worry about the political trial, and the head of the regiment Dai will not recommend it to him if he fails the political trial. Moreover, in terms of security capabilities, the people who come out of the army are far stronger than those recruited through ordinary means, and even basic training can be omitted, and they can directly take up their posts.

From its establishment to the present, not to mention criminal cases such as material theft, the Jinling Institute for Advanced Study has not even lost a piece of scratch paper, relying on these lovely people who are dedicated to their duties.

took Academician Xue to the office, and Lu Zhou instructed the secretary to pour him a cup of tea and a cup of coffee for himself.

When he had done this, the secretary left the office with great amusement and closed the door.

Watching the door close, Lu Zhou continued to look at the old gentleman sitting across from him, smiled and said.

"I guess you have a lot of things you want to ask, so please ask for them first."

Academician Xue was silent for a while, then sighed softly and said.

"Before I came here, I did have a lot of confusion, but now ...... I feel like I've got the answer. Not to mention ......"

The old academician's smile carried a faint mixed feeling.

“…… Cryptography can already be withdrawn from the stage of history. ”

Lu Zhou shook his head.

"This statement is so absolute, it takes time for any technology to be upgraded, just as even with clean and efficient energy sources such as fusion energy, coal power still occupies a small part of the market share in our large western region......

"What's more, it is only the application of encryption algorithms in long-distance communication that has withdrawn from the stage of history, and cryptography can still play a significant role in short-distance communication from base stations to individuals, as well as in other fields......"

After a pause, Lu Zhou looked at Academician Xue and continued.

“…… All that is needed is to make some adjustments. ”

Repeatedly chewing on the words of the landing boat, Academician Xue fell into deep thought.

Without disturbing his thinking, Lu Zhou picked up the coffee cup, blew the curling white mist, and took a sip slowly.

After about five minutes, Academician Xue finally raised his head and said seriously.

"Is there anything I can do to help?"

An approving smile appeared on Lu Zhou's face.

"Of course."

"I have a few questions that I need to consult with experts in the relevant field."

Academician Xue: "What? ”

"About quantum communication."

Hearing this, Academician Xue was slightly stunned, and said with a slightly embarrassed expression: "Quantum communication...... I'm not an expert on this, you should go to a professor at HKUST......"

"I had already emailed the professors at HKUST long before you came here, and after hearing my questions, they recommended you to me."

Looking at Academician Xue, Lu Zhou continued, "In addition to cryptography, you are also an expert in the field of communication engineering, once served as a senior engineer in China Electronics 46 Institute, and participated in the construction of early optical fiber networks in China. ”

Hearing these nostalgic things, a few memories appeared in Academician Xue's eyes.

Eventually, though, he shook his head.

"That's all old, I've basically switched to communication security since 10 years, I'm afraid it's hard to help you."

"But I believe that experience is not going to go out of style," Lu Zhou said seriously, "especially when we need to re-establish this communication network." ”

The moment he heard this, Academician Xue's heart was shocked, and he looked at Lu Zhou in disbelief.

"You mean, you're going to ...... Are you going to use that kind of ...... Quantum fiber? Rebuilding the domestic communications network? ”

"That's not my intention."

Looking at Academician Xue, whose voice had begun to be incoherent, Lu Zhou smiled faintly and continued in a joking tone.

"And I didn't say it's just domestic."

……

Once the problem of quantum repeater is solved, the entire quantum communication technology has the possibility of commercialization.

However, quantum communication technology has a fatal drawback, that is, the amount of data transmitted per unit of time.

For example, the bandwidth of submarine fiber optic cables from the West Coast of the United States to the East Coast of China is often measured in Tbps.

This scale of data is not a difficult task for traditional optical fibers, but it is a problem that cannot be solved in the short term for quantum communication technology that relies on single-photon entangled pairs to achieve information transfer.

To put it simply, the communication channel based on quantum communication technology has no problem to meet the data exchange between a limited number of enterprises, but it cannot carry the communication of this scale of the Internet.

However, this is not without a solution.

According to IST FP5, a 128-bit key can secure 100 Gbit. Theoretically, all it takes is a quantum communication channel with a bandwidth of the order of Mtps, which is enough to add a lock to all information across the Pacific Ocean.

Therefore, a perfect solution is to combine traditional communication means with quantum communication technology, use traditional communication channels to send "locked" messages, and then use quantum communication channels to distribute "unlocked" keys.

The abstract description is that the big hand sends the package, and the small hand hands hand the key.

This encryption method, which is similar to "one password at a time", can theoretically reach the level of "unconditional security". If there is only one unique key to unlocking, then no matter how fast the computer is, it is impossible to steal the key through pure computing power.

In order to achieve the separation of the key and the encrypted information, a new set of communication protocols is required. Not only that, but in order to improve the efficiency of information transmission, the quantum communication network used to distribute keys must be carefully designed.

Admittedly, this is not an easy job.

But in any case, it is still much easier than quantum repeaters.

Almost without any hesitation, Academician Xue accepted Lu Zhou's invitation on the spot and participated in the project of building a quantum communication network, staying at Jinling University in the name of visiting and exchanging.

It just so happened that he was still worrying about how to avoid those colleagues and old friends who were waiting for him to go to the Ministry of Industry and Information Technology to "ask for an explanation".

Although it is easy to keep his mouth shut, the circle of the industry he is engaged in is too small.

There are many things that even if he doesn't say anything, others can guess everything with a single look.

Whether it's for the sake of the big picture, or for himself, leaving for a while is the best option......

With the addition of Academician Xue, the speed of the entire quantum communication network project can be described as godfast. With the experience of this old gentleman, Lu Zhou quickly found the optimal method of combining quantum communication technology with traditional communication technology, and completed a structural framework for this new communication protocol.

In this way, time passed day by day, and finally it was the last day of April.

A quantum communication pipeline for experiments with a length of about 500 meters was built in a hidden corner of the Jinling Institute for Advanced Study. At the same time, this ivory tower, which stands at the top of China's academic circles, has also welcomed a special guest......

Lamp pen