Chapter 242 There is something new every time
In the living room, after cleaning up Xu Qingzhou, Song Yao got up from the sofa angrily, her cheeks redder than before, her bulging chest rising and falling rapidly, and her breathing was heavy.
Xu Qingzhou handed her water with a wink: "You are tired, drink some water."
Being beaten and having to worry about whether she was thirsty or not was too difficult.
Song Yao took the cup, thinking that this guy was a bit discerning, and drank the water. She was too lazy to pay attention to this lecherous guy. Seeing that the time was almost up, she stepped on her slippers and went to the kitchen to cook.
"I'm here to help."
Xu Qingzhou ran into the kitchen to help peel the garlic. After peeling, he leaned against the door and watched her cooking.
Although he received a heavy beating and the flesh on his waist was stinging, he had already touched what needed to be touched, and he was in a good mood.
Everything is difficult at the beginning, but then, hey.
Song Yao’s beautiful little face has a cold expression, and she is slim, and she has an aura of keeping strangers away. To be honest, , no matter how you look at it, the aloof school beauty Song is not a good match for the kitchen.
But Xu Qingzhou had already cooked twice, and this time Song Yao insisted on doing it herself.
"You, go to the living room and stay by yourself." Song Yao pointed at Xu Qingzhou with the green onions, not wanting to see this annoying guy for the time being.
Hmph, it’s broad daylight and I’m thinking about weird things.
Xu Qingzhou shrugged, hummed a little tune and returned to his seat, intending to continue working on the quantum satellite thesis.
As far as quantum communication is concerned, entanglement is a fundamental resource in quantum communication.
However, during the entanglement distribution process, due to channel noise, the quality of long-distance shared entangled photon pairs will decrease to a certain extent, thus affecting the quality of quantum communication.
For this problem, Xu Qingzhou once found a very useful method when he was in his second year of Ph.D.—Xu's entanglement pair purification theory.
Entangled pair purification, also called entanglement distillation, is to extract highly entangled quantum pairs from a group of partially entangled quantum pairs.
But at this period, the purification theory was not mature, because in actual physical systems, environmental interference and noise often cause damage to the entangled state, making the purification process very difficult.
Moreover, the current quantum purification theory requires the use of controlled NOT gates, but accurate and efficient controlled NOT gates cannot be realized with current technology.
Xu Qingzhou's method does not require the use of controlled NOT gates. As long as the initial noise is lower than a certain level, fewer pairs of purely entangled pairs can be extracted. The absolute value can be obtained by measuring the same basis vector at both ends of the purely entangled pairs. Secure passwords.
Purification efficiency can theoretically be increased by 1.5 billion times.
[p=|bb'l+|ba'l+\bb'l'+|ba'l=2|b'l]
This result is exactly the same as Alice's Bell state measurement .
【When |a'l≥lal≥lbl≥lb'|.】
[It can be seen from the above analysis that the success probability of teleportation is determined by the smaller value of |b'| and |b|, that is, the one with the smaller degree of entanglement between the generalized Bell basis used in Alice's measurement and the quantum channel Decide. 】
June 12th, early morning.
Xu Qingzhou came to the institute again. This time he did not go to classroom 4102, but went directly to the conference room on the second floor. There were many familiar people here, including academician Ma Zailiang, Wang Yigui, and intern He who was like him. when.
“Xiao Xu is here.”
The thin middle-aged man next to Academician Ma spoke with a smile. This is Professor Pan Jianwei, the chief engineer of the project.
"Professor Pan, Academician Ma." Xu Qingzhou greeted the two of them.
"Sit down first, we will start later." Professor Pan nodded, and after speaking, he lowered his head and wrote calculations on the manuscript paper in front of him.
Xu Qingzhou looked around the conference room, and finally walked to sit next to He Dang.
He Dang greeted Xu Qingzhou: "Good morning, junior brother."
"Good morning." Xu Qingzhou responded with a smile.
At this time, Wang Yigui also walked in. As soon as he sat down, he asked anxiously: "Is everything going well for you there?"
"It went well." Xu Qingzhou said.
"Tsk tsk, as expected of my junior brother, I have a calculation stuck here. The calculated value is wrong no matter how I look at it. Please help me take a look later if you have time."
< br>"Okay, let's study it after the meeting." Xu Qingzhou smiled and nodded.
On the side, watching Dr. Wang asking Xu Qingzhou for help, He Dang sighed helplessly, a little envious. He was also an intern, and he could only do chores at the moment.
Xu Qingzhou has become an indispensable part of the project.
At 9 o'clock, the meeting started. This time it was chaired by Professor Pan. Everyone reported on the progress of their work. They were basically completed on time. If there were still problems, they came down to discuss.
After summarizing, of course there is still work content in the next stage, which is mainly about the coupling of the model and the performance testing of the entanglement source. "Here, the wave function of the entire system can be expressed as the tensor product of the wave functions of these two subsystems."
"I have a request. When doing numerical calculations, you need to choose Stable algorithm and appropriate calculation accuracy to avoid calculation instability caused by rounding errors, overflows and other problems during the calculation process. ”
Professor Pan paused, looked at everyone, and said:
“Okay, these are the specific frameworks. Now everyone can supplement the existing frameworks or put forward new perspectives.”
Academician Ma and the others all shook their heads, and naturally no one had anything to add.
Wang Yigui saw that Xu Qingzhou was deep in thought and asked in a low voice: "Junior brother, where are you?"
During the time we got together, he had seen how awesome this junior brother was, and every time Can come up with something new.
However, because the conference room was very quiet, the sound was particularly noticeable, and even Professor Pan and others' eyes fell on Xu Qingzhou.
“I have no idea about this part of the work.” Xu Qingzhou shook his head. Frankly speaking, this performance test on quantum entanglement sources is well written.
It completely includes key indicators such as entanglement, stability, and transmission efficiency. Even if you look at it from the perspective of more than ten years in the future, you can't find any faults.
If you think about it carefully, it seems normal. Both Professor Pan and Academician Ma are world-class experts in the field of quantum communications.
Especially Professor Pan, how could someone who can preside over the creation of the world's first quantum satellite be so bad?
"Huh~"
Next door, when he saw Xu Qingzhou shaking his head, He Dangchang breathed a sigh of relief, and the threat finally diminished.
Although I have always heard that my junior fellow students are very powerful, this plan was written by Professor Pan and Academician Ma after discussion.
What can be the problem?
A false alarm.
Mainly due to the influence of Xuemei Deng during this period, he said that this junior fellow student was so unbelievable, which made him, a first-year undergraduate intern, very stressed.
Junior sister Cai Yanyi, it is normal for her to be crushed.
He is now a Bo Yi after all, and has participated in many experiments, large and small.
He Dang continued to provide psychological comfort.
Then, he heard Xu Qingzhou say: "However, I wrote a paper, which contains thoughts on quantum entanglement, including quantum secure communication of entangled photon pairs, hidden transmission of quantum states, entangled photons Control these things correctly.”
"In addition, when I was studying quantum purification theory, I calculated an efficient and accurate method, which should be helpful for our future experiments."
As he said that, Xu Qingzhou handed the USB flash drive to Professor Pan.
He Dang: "."
Professor Pan nodded slightly and inserted the USB flash drive into the computer. He was looking forward to the new ideas this young man said.
Academician Ma does not have high expectations for things like the hidden transmission of quantum states that Xu Qingzhou mentioned earlier, because he and Professor Pan are already top experts in this field.
Young people need to be supported if they are enterprising.
No matter what the new idea this little guy said, you have to encourage it.
As for entanglement and purification, there is currently no effective way to do this, and he doesn't think Xu Qingzhou has really made any substantial progress.
Several other people also had a faint smile on their faces, relaxed, stared at the projection in front of them curiously, and talked about quantum entanglement in front of Professor Pan and Academician Ma.
Young man, a little arrogant. La.
Dr. Wang sighed in his heart and regretted asking his junior brother just now. If he hadn't asked, his junior brother might not have presented that paper at the meeting.
It’s like playing a machete in front of Guan Gong now.
Since the computer was connected to the projection, the paper appeared in front of everyone quickly.
[Quantum entanglement and quantum operations]
[Abstract: This article reviews the basic principles, methods, technical means and applications of quantum communication, and introduces the implicit transmission of quantum states and entangled photon pairs based on quantum entanglement Control.】
[Keywords: quantum communication, quantum key distribution, quantum teleportation, manipulation of entangled photons]
(End of this chapter)