Chapter 158 I Found the Problem
The reason why Xu You was so eager to go to Wang Xiangwu was not just because he was attracted by Wang Xiangwu's topic.
Indeed, during this period, no further progress was made on the subject of the mechanisms of high-temperature superconductors.
Because this topic is so complex, each breakthrough in a small stage is even more difficult than solving an ordinary topic.
Xu You would often fall into a bottleneck and find it difficult to continue to advance this project.
It just so happened that Wang Xiangwu had another project, and Xu You also felt that he could not put all his energy on a project that was in a stalemate.
Moreover, as Wang Xiangwu mentioned before, there are similarities between condensed matter physics and quantum physics.
Xu You indeed felt so.
In the entire field of physics, condensed matter physics and quantum physics can indeed be regarded as two closely related branches of disciplines.
Maybe Xu You can really get some new ideas from Wang Xiangwu's laboratory.
When Xu You arrived at the quantum physics laboratory, Zhao Weijia came to greet him immediately.
"Xu You! It's all thanks to you that I can appear on CCTV! You know, there are so many girls asking me out recently, the line is almost stretched from Jida to Jinghua."
Xu You thought about it and it seemed that there weren’t that many people.
"So, Brother, after so many days, you're still on a blind date?"
Hearing Xu You's words, Zhao Weijia smiled awkwardly.
"Dating is like picking fruit in an orchard. You are only allowed to pick one. When you come across an okay fruit, you always wonder if you can find a better one later. But as you go along, you find that the previous fruit is better. But when you go back to look for that fruit, you find that it has been picked by someone else."
"Is it possible that some good fruits are unwilling to be picked by you?"
"this……"
After they chatted for a while, they started to get down to business.
"Xu You, you are here today because Teacher Wang asked you to participate in our new project. Teacher Wang is not here, so I will first give you a brief introduction to what this project is about."
Listening to Zhao Weijia's story, Xu You quickly understood the main research content of this topic.
This topic mainly studies the quantum phase transition of two different lattice models.
The so-called quantum phase change, to put it simply, is the change in the quantum state of matter caused by the change of some non-thermodynamic order parameters.
These order parameters include pressure, magnetic field, doping, etc.
As he listened, Xu You also understood what the main problems encountered in the current project were.
"So, the numerical results of the Jaynes-Cummings lattice model and the Rabi lattice model quantum phase transition have a large error compared to the theory?"
Zhao Weijia also nodded when he heard this.
"How should I describe this error? It's not too big, but it's not ideal. We have tried various methods to remeasure the numerical results, but we haven't gotten any satisfactory data. Professor Wang said that it would be better to further control this error."
"Let me see the data first."
Xu You was not in a hurry to analyze the reasons, but wanted to understand more details of the experiment before making his own judgment.
"Okay, I'll find it for you right away."
In front of Xu You, Zhao Weijia's attitude was very good, as if Xu You was a professor.
Of course, in terms of knowledge and ability, Xu You is indeed about to reach the level of professor.
Immediately, Zhao Weijia found the corresponding data on the computer.
Xu You looked at it carefully and indeed felt that there seemed to be some problems inside.
These data gave Xu You a strange feeling.
Although such an error is still within an acceptable range.
But it is only on the edge of being qualified.
Xu You vaguely felt that such a result might be very dangerous.
It may even affect key conclusions.
"Brother, let me take a look at the formula."
"Okay, wait a moment."
As he spoke, Zhao Weijia found the part of the formula in the paper and explained the derivation process of the formula.
At this moment, Xu You suddenly noticed a detail.
"Wait a minute! Brother, this part uses an approximation, right?"
"Yes, we took an approximation for the phase transition here. Theoretically, the approximation here should be negligible."
Xu You also knew this way of dealing with it.
Indeed, in theory, the impact of such approximation on the results is very small, so small that it can be completely ignored.
But the final error value is likely related to the approximation here.
Xu You continued to browse the experimental process and data processing methods in the paper, and kept thinking about something.
Finally, after repeated review and thinking.
Xu You found out the problem.
"Brother, although theoretically, the error of this approximation can be ignored. But in fact, there is a processing behind it that will amplify the error, so it will cause problems in the fitting of the numerical results."
After listening to Xu You's explanation, Zhao Weijia analyzed it again and finally understood the problem Xu You mentioned.
"I see. If you hadn't told us, we wouldn't have discovered this problem at all."
Because everyone is used to this approximate processing, they subconsciously do not think it is problematic.
"But, Xu You , if we don't do approximate processing here, then this result cannot be expressed."
Because the formula where the problem occurs is theoretically a formula of infinite length.
Only through approximation can the final result be expressed.
Otherwise, calculations would be impossible.
"Yes, brother, I've been thinking about this question as well."
At this time, Wang Xiangwu also came to the laboratory.
"Xu You, you're here."
"Yes, I am here, teacher."
"Has Weijia explained the problem to you?"
"Yes, Senior Brother has explained the problem. We have just found out what caused the problem."
Hearing this , Wang Xiangwu was also shocked.
This problem has been discussed for several days, but no specific reason has been found.
Xu You has just come to the laboratory and he has already found the cause?
"What's the reason? Tell me!"
Next, Xu You repeated to Wang Xiangwu what he had just said to Zhao Weijia.
Wang Xiangwu's reaction speed was obviously much faster than Zhao Weijia's, but it took him a while to figure out the reason.
"Sure enough, I felt that there was something wrong. Fortunately, I asked you to come here, otherwise I don't know when we can find the reason."
At this time, everyone fell into deep thought .
