Great Country Academician

The end of the report does not mean the end of this report meeting.

For a report meeting on the results of natural sciences such as mathematical physics, the question-and-answer session is the real challenge.

For many researchers, submitting a conference paper is nerve-wracking, and answering questions is even more difficult.

Because the reporter not only has to answer questions from everyone present, but sometimes those questions are often long speeches with pretentious humility, rambling self-statements and unabashed intellectual showing off.

To put it simply, you may encounter some pretenders during the question-and-answer session.

Of course, at Xu Chuan's report meeting, this situation was impossible.

After all, when it comes to pretending, well, when it comes to advanced operations, who can beat him in his report meeting?

When the applause in the auditorium subsided, Xu Chuan stood back at the reporting table, picked up the microphone and spoke again:

"This concludes the report on the unified framework of the strongly correlated electronic system. If you have any questions, please feel free to ask them and I will do my best to answer them."

For strongly correlated electronic systems, the most important thing for the physics community is the introduction of the concept of dimensional space and the corresponding mathematical methods in the entire paper.

If you can control these things, it will not be difficult to understand this paper.

As Xu Chuan's words fell, arms one after another in the auditorium were raised with a 'swish'.

Starting from the front row, Xu Chuan began to answer questions.

For this kind of report meeting, the selection of people is naturally based on the speaker's own arrangements.

The first questioner was Frank Wilczek, winner of the 2004 Nobel Prize in Physics. He is mainly engaged in research in the fields of condensed matter physics, astrophysics and particle physics.

The boss asked two questions related to calculation methods of low-dimensional mathematical theory, and sat down after receiving perfect answers from Xu Chuan.

A close second was Michael Kosterlitz.

The 16-year Nobel Prize winner in physics mainly researches condensed matter theory and one-dimensional/two-dimensional physics.

When Xu Chuan signaled him to ask a question, Kosterlitz quickly stood up and took the microphone from the staff with some excitement and expectation.

"When electron-electron correlation interactions are introduced in topological quantum materials, complex novel ordered phases will be produced in the system, but how to explain this mathematically is still a mystery."

"How did Professor Xu see this difficult problem? Does it have a strict model and analytical solution?"

As a scholar who studies topological phase transitions and topological phases of matter, he has been looking for a way to unify topological phase transitions and strongly correlated electronic systems.

But unfortunately, even if he could start from mathematics and use topology to study topological phase transitions and topological phase substances of physical materials, he still could not find a suitable path.

But now, in this young scholar on the stage, he sees the hope of a breakthrough.

Of course, what he didn't know was that the path he longed for and hoped for had already been opened up.

On the reporting table, upon hearing this question, Xu Chuan immediately knew what the other party was thinking.

Establish a unified theory for topological phase transitions and strongly correlated systems, and then conduct in-depth research on topological quantum materials.

This was work that he had been busy with a few days ago. Unexpectedly, someone wanted to go with him today.

After pondering for a moment, Xu Chuan said: "This is one of the unsolved problems in the strong correlation system. Unifying the strong correlation system and the topological state of matter."

"Theoretically, it is possible to unify topological states into the framework of a strongly correlated electronic system, but I have not studied this aspect in depth. Perhaps you can consider the non-trivial multi-band quantum features of hybrid mixed orbitals. Geometric methods.”

"This route has now shown many physical phenomena, which can also be explained through mathematical methods, and it may be possible to extend it."

Although he had completed this theory, he could not explain it clearly, nor could he explain it in his paper.

After all, topological quantum materials involve the research of quantum computers and are of considerable importance.

But at the report meeting, fellow scholars in the audience had already raised questions, and it was impossible for him to say nothing.

Listening to Xu Chuan's answer, Professor Kosterlitz fell into thinking and sat down unknowingly.

Seeing this, Xu Chuan jumped over him and continued to ask questions.

The person who stood up immediately after was Professor David Gross, the director of CERN.

Like Frank Wilczek, he was also the winner of the 2004 Nobel Prize in Physics.

And nominally speaking, this great man is also the ancestor of Xu Chuan.

Because he is Witten's mentor, theoretically, he is on the same level as Alexander Grothendieck.

Of course, in terms of influence in their respective fields, Gross is definitely not as good as Grothendieck. After all, the latter is known as the founder of modern algebraic geometry and the greatest mathematician of the 20th century.

But Professor Gross's achievements are not low, and can even be said to be very high.

He is the founder of 'hybrid string theory', the founder of asymptotic freedom in the strong interaction theory, one of the main founders of quantum chromodynamics, and a recognized leader in modern physics.

In today's physics community, his status does not mean that he can compete for the top three, but he should have no problem competing for the top five.

This time he came over. On the one hand, the unified framework theory of strongly correlated electronic systems was indeed within his research scope.

On the other hand, they are preparing to dock with Xu Chuan to exchange information on cooperation matters in the construction of CERN and China's Large Strong Particle Collider.

Although CERN is still debating whether to continue building the high-brightness LC-LHC hadron collider, I am afraid there is not much hope.

With the rise of China, the decline of the United States and the European Union is inevitable.

In the economic downturn cycle, the importance of basic scientific research equipment such as the Large Strong Particle Collider, which is expensive, extremely troublesome to invest in and maintain, and requires a huge amount of money, does not appear to be so high.

Of course, the question he asked at the report conference today must have nothing to do with the collider, but only the strongly correlated electronic system.

After all, this is the unspoken rule of the lecture meeting, and it is also the necessary respect and etiquette for academic speakers.

After standing up, Professor Gross thought and organized his words, and then said: "In the thirty-first page of the paper, I noticed the topological insulator effect formed by the strongly correlated electronic effect in the two-dimensional state that you proposed."

"This study first proposes a minimal continuous model of the p+ip exciton phase and proposes a new topological invariant, the chiral Chen number, to characterize the topological properties of the system."

"But in the two-dimensional minimum two-component model, although the traditional Chern number of the topological exciton insulating phase is zero, it has a chiral Chern number of one-half. Can the reporter explain this?"

Hearing this, Xu Chuan lowered his head and flipped through the paper: "Thirty-one pages?"

"Simply speaking, this new topological insulator is formed by the exciton condensation of the p+ip wave function. Its mechanism is similar to the p+ip wave Cooper pair condensation that leads to the famous topological superconductor."

"There will be Majorana fermions in the vortex of topological superconductors, and there will be 1/2 charge quasiparticles in the vortex of topological exciton insulators. But unlike p+ip topological superconductors and Chen insulators, this new The traditional Chern number of topological exciton insulators is zero, so its topological properties are characterized by the "chiral Chern number" newly proposed by the research group."

"In addition, the condensation of p+ip excitons will also lead to the breaking of in-plane spontaneous magnetization and time reversal symmetry"

Before Xu Chuan finished speaking, Professor David Gross interrupted him.

"I know this. What I want to know is how you define that strong electron-electron interaction will produce a scattering channel with p-wave symmetry."

"If I remember correctly, this part of the theory involves small polarons in the strong electron-phonon interaction system. However, this is still an unsolved problem."

Standing in the audience, David Gross looked at the young man on the reporting table and slowly expressed his doubts.

His voice was not loud, but it sounded like thunder in the entire auditorium, attracting the attention of everyone present.

Listening to his mentor's question, Edward Witten's dark green pupils instantly condensed, and his breathing quickened.

This is a flaw that he did not discover, and perhaps few people in the entire physics community have noticed this extremely subtle key point.

Professor Michael Kosterlitz, who was sitting next to him and had just finished asking the question, was stunned for a moment. Then he quickly bent down and took out the paper from the backpack placed on the corner of the chair, and found page 31 of the paper.

Looking at the theories and mathematical formulas in the paper, he quickly calculated in his mind.

The small polaron problem in a system with strong electron-phonon interaction is a problem in a system with strong electron-phonon interaction. It was extensively studied in the 1960s to 1980s.

However, with the subsequent discovery of strong electronic coupling systems represented by high-temperature superconductors, research in this area is no longer mainstream. There is no complete set of theoretical images that can uniformly solve this problem.

He did not expect to find this deeply hidden point in the paper.

Now, for Professor Xu, this may be a "fatal" flaw in the unified framework of strongly correlated electronic systems.

PS: There will be another chapter tonight