Chapter 1188 Unconditional Safety

It's time to do something when you're full.

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

However, 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 made on the phone yesterday, Lu Zhou probably guessed who it was. He threw the tissue into the packing box, tied the plastic bag tightly and put it aside, cleared his throat and said.

"Please come in."

The door of the office was pushed open, and Director Li's familiar and unsurprising face appeared at the door. Seeing the packing box next to the table, he was about to say hello with a smile, and his face couldn't help showing a smile. Surprised look.

"...You eat this at noon?"

Lu Zhou gave him a strange look.

"Two meat and one vegetarian, is there a problem?"

"Uh, no..."

"If you don't, let's get down to business. After three o'clock in the afternoon, I have to go back to the Institute for Advanced Study for a meeting about the work of the Lunar Orbit Construction Committee." Lu Zhou glanced at the time on his watch and looked at Director Li. He continued, "What exactly did you tell me on the phone yesterday?"

Director Li didn't speak, but glanced at Wang Peng.

Wang Peng nodded, picked up the packing box knowingly and exited the office, and closed the door behind him.

There were only two people left in the office.

Seeing that there were no other people, Director Li spoke up.

"It's about the quantum encryption algorithm."

Upon hearing this, Lu Zhou raised his eyebrows with interest and asked.

"easy to use?"

"It's easy to use! It's really 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 was so surprised that he almost didn't chin on the ground..."

Seeing this guy happily describing it, Lu Zhou always had a bad feeling.

Every time the old man courted him, it was either to introduce someone to him, or to trouble him with something.

"...Since it's easy to use, why do you still come to me?"

Director Li said with a hey smile.

"Didn't you say some time ago that after your carbon-based topological quantum processor chip comes out, it won't be long before the quantum computer can break through 1,000 qubits?"

Lu Zhou thought for a while, then nodded.

"I seem to have said so."

"That's why!" Clapping his palms, Director Li continued, "The Ministry had a meeting a few days ago to discuss this issue, but we really lack experts in this field, and we couldn't discuss it for a long time. This is 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 said with a sigh, "...you just tell me what's bothering you."

"It's not a troublesome thing, I just want to ask for your opinion," Director Li smiled sheepishly and asked, "... When will this 2000-qubit computer be released?"

As soon as he heard Director Li's words, Lu Zhou immediately understood what he was thinking. He was worried about the timeliness of technology for a long time.

However, it is inevitable that individuals will generally have such concerns.

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

Replacing the encryption algorithm is not a trivial matter such as changing the Penguin password. It involves the reform of the entire communication field, and the hidden social costs that need to be paid are difficult to measure simply by money.

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

Don't update the encryption algorithm every three to five years. No matter how tough Huaguo's financial industry, communication industry, and Internet industry are, they can't stand such a toss...

"Your worry is not unreasonable," Lu Zhou tapped his index finger on the table, and after thinking for a moment, he said, "But this thing is really hard to say. I can only tell you that the bottleneck of 1000 qubits is It can break through in a short period of time, but 2000 qubits... at least I can give you an accurate estimate until 1000 qubits break through."

Director Li wondered: "I guess it won't work even once?"

"It's not a matter of estimation, but it's meaningless at all," Lu Zhou sighed, "If you just want to seek psychological comfort, why don't you ask a fortune teller? From the perspective of probability, it's 50-50 anyway. And ..."

After a pause, Lu Zhou continued.

"The quantum encryption algorithm is always only temporary. n qubits correspond to 2^n states, not 2 multiplied by n. In theory, if it is only linearly increasing the difficulty of propositions, one day our encryption methods will can’t keep up with the pace of our information technology development.”

There was silence in the office.

Repeatedly chewing on Lu Zhou's words, Director Li pondered for a long time, and then asked 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 secrets can be eliminated from the means of communication!"

"You mean...quantum communication?"

Lu Zhou nodded approvingly.

"Exactly."

Director Li's expression was a little solemn.

"... But I heard that quantum communication technology is not simple, right? Our country is still ahead of the curve in this area, and there are many achievements, but I have never seen signs of this technology becoming mature."

"It's normal not to see this sign," Lu Zhou said, "because breakthroughs in this field are mainly focused on realizing photon entanglement and enhancing signal strength, but the key to truly realizing quantum communication lies in quantum repeaters. superior."

If it is further subdivided, quantum repeaters can also be subdivided into two propositions: "quantum memory" and "optimization of efficiency and storage time for writing and reading quantum states".

These two major technical difficulties are exactly mentioned in the DLCZ scheme, which uses the combination of quantum memory and single photon channel to suppress attenuation to realize long-distance quantum communication.

However, since there is basically no major progress in quantum memory, quantum communication can only be realized within a distance of 100 kilometers, and the requirements for the transmission environment are extremely stringent. And this has lost its practical value, and it was even suspected that it was impossible to realize.

"Quantum repeater?"

"Well," looking at the thoughtful Director Li, Lu Zhou nodded, "It's not that there is no progress in this area, but 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 the wave function. Once the photons transmitting information are intercepted, any observation behavior will lead to the collapse of the entangled state.

To put it more simply, if A and B make a call, if there is a third party C standing in the middle to eavesdrop. No matter what method C adopts, using a bug or sticking his ear to the wall, as long as C hears a word, A and B will immediately know that the communication has been tapped, and the entire message will lose its meaning.

All encryption algorithms, including asymmetric encryption algorithms, are aimed at traditional means of communication. In the face of quantum communication technology, encryption is simply redundant.

This is the so-called "unconditional security"!

It took about five minutes for Lu Zhou to briefly explain the technical difficulties of quantum communication and its advantages over traditional communication methods to Director Li.

Although they were all clichés, Director Li had heard many people say similar things to him before, but this time it was from Academician Lu's mouth after all, and the meaning was different in an instant.

After listening to Lu Zhou's explanation, his heart suddenly became hot, and he hurriedly asked.

"Is this 'unconditionally secure' quantum communication difficult?"

Lu Zhou nodded seriously.

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

"Leaving aside the parts that you don't understand even after I've said it, you just need to know that this thing is basically the core bottleneck that restricts the commercialization of quantum communication technology."

The office was quiet again.

This time the silence was a little longer.

Lu Zhou took a sip from the water glass on the table, moistened the mulberries, and was about to comfort the old friend, and told him not to worry too much. That set of encryption algorithms can be used first, and when the 2000-qubit computer comes out, there may be new progress in the research of quantum repeaters.

The birth of any new technology takes time to settle. Although the quantum encryption algorithm he developed is not particularly brilliant in his own opinion, it will be fine for a while.

However, just as he was about to speak, Director Li couldn't help but take a step ahead.

"...Then, that quantum repeater, can you handle it?"

Lu Zhou: "........."