Starting from a top student and marching towards the sea of ​​stars

Chapter 153 I said I thought of it, do you believe it?
Seeing the dot contact spectrum on the computer screen, Ren Mingshan's eyes couldn't help but widen.

"You actually... made such an obvious zero-voltage conductivity peak?"

At this time, Ren Mingshan couldn't believe that Ning Chen and Qi Wan were able to make such a big breakthrough in the project after only being away for a few days.

"Yes, Teacher Ren, we measured the impact of the magnetic field on the zero-voltage conductance peak and found that there is a relatively close influence between the two. So we added a magnetic field shielding device outside the superconducting circuit, and finally measured The most ideal primary zero-voltage conductivity peak.”

Ren Mingshan carefully observed the data on the screen, and his brain was constantly thinking about something.

In fact, Ren Mingshan had been able to predict the impact of the magnetic field on the zero-voltage conductivity peak before.

However, Ren Mingshan feels that this influence is relatively weak. Even if the research is conducted on magnetic fields, it can only enrich the data of some papers, and it will not play a decisive role in the research of the subject.

However, according to the experimental results obtained by Ning Chen and Qi Wan, it was shown that Ren Mingshan's previous prediction of the impact of magnetic fields on the zero-voltage conductivity peak was not accurate.

After thinking for a while, Ren Mingshan asked first:
"Who came up with this experimental idea?"

After hearing what Ren Mingshan said, Qi Wan replied:
"Teacher Ren, I said I thought of it, do you believe it?"

Ren Mingshan smiled helplessly when he heard this. If Qi Wan could reach such a level of scientific research now, then Ren Mingshan would probably be able to laugh even in his dreams.

In fact, no need for Qi Wan to say, Ren Mingshan also knew that the only one who could come up with this experimental idea was Ning Chen.

Thinking of this, Ren Mingshan asked for advice again and said:
"Ning Chen, I have also considered the influence of magnetic fields before, but this influence should be relatively weak, especially the magnetic field intensity of the geomagnetic field is very low. I really didn't expect that such a weak magnetic field can also affect zero piezoelectricity. Daofeng has such an obvious influence."

"Teacher Ren, please take a look at this formula."

Ning Chen handed the draft paper on which he had previously derived the formula to Ren Mingshan, and explained his ideas for making such a derivation.

Because it involves a lot of complex mathematical knowledge, even Ren Mingshan found it difficult to listen.

Physics experts generally have very good mathematical foundations, but when compared with mathematics experts, there are still very few who can reach the same level.

After all, there are specialties in the field, and it is not easy to study the knowledge in a small field thoroughly.

However, under Ning Chen's careful explanation, Ren Mingshan still understood the theory in Ning Chen's formula.

"Ning Chen, according to your opinion, the lower the intensity of the magnetic field, the more obvious the impact on the zero-voltage conductivity peak?"

"Yes, it can indeed be understood this way. It is a bit like a power function with an exponent between 0 and 1. When the base is very small, the image changes at the fastest speed."

Of course, Ning Chen's actual formula is much more complicated than this. If Ning Chen really started talking about it, he wouldn't be able to finish it in just a few hours.

But after all, this is a physics topic, and Ning Chen feels there is no need to focus on it.

"Judging from the results of the current experiment, your conjecture is indeed likely to be correct. I think the magnetic field shielding device you made yourself is a bit too crude when we conduct some more rigorous experiments."

This so-called magnetic field shielding device was completely handmade by Ning Chen and Qi Wan.

What Ren Mingshan said as "simple" is actually a way of saving face. To put it bluntly, they just spliced ​​some iron plates together.

"Teacher Ren, do we have a more ideal magnetic field shielding device?"

"I'll make a call later and borrow a three-dimensional Helmholtz coil. This is a simulation system specially designed to shield the geomagnetic field. The effect of using this thing to shield the geomagnetic field will definitely be better."

This was the first time Ning Chen had heard of the "three-dimensional Helmholtz coil", but based on its name, Ning Chen probably knew its function.

If Ning Chen guessed correctly, this should be a device that can simulate various magnetic fields and can also be used to offset the effects of various magnetic fields.

After talking to Ning Chen, Ren Mingshan took out his mobile phone and made a call. Not long after, several students brought a piece of equipment over.

"This is a three-dimensional Helmholtz coil. It can be used to generate low and weak three-dimensional magnetic fields, simulate the earth's magnetic field, actively shield weak magnetic fields, etc..."

Ren Mingshan's words well confirmed Ning Chen's conjecture just now.After briefly introducing the equipment, Ren Mingshan continued:

"Because of time constraints, I won't teach you how to use this equipment in detail. I will just debug the equipment, and then we will start doing experiments."

Judging from Ren Mingshan's appearance, he planned to do experiments with Ning Chen and Qi Wan today. Ning Chen was happy to do so. With an academic master like Ren Mingshan, he could accumulate subject experience faster.

Immediately, Ren Mingshan began to debug the three-dimensional Helmholtz coil, while Ning Chen and Qi Wan prepared the measurements for the topological superconducting experiment.

While preparing for the superconducting experiment, Ning Chen was also observing Ren Mingshan from time to time, hoping to learn something from it.

Ning Chen could see that Ren Mingshan was no stranger to the use of three-dimensional Helmholtz coils, and he quickly completed the debugging of the equipment.

"Now we first measure the surrounding magnetic field, and then we use a three-dimensional Helmholtz coil to generate a low and weak three-dimensional magnetic field to offset the external magnetic field, thereby achieving the shielding effect of the magnetic field."

Although Ren Mingshan did not teach Ning Chen and Qi Wan in detail how to use this equipment, he would explain some experimental principles from time to time during the experiment.

With just this limited information, Ning Chen has almost mastered the use of this instrument.

At this time, in the computer software interface, Ren Mingshan has constructed a complete three-dimensional magnetic field in this space.

Ren Mingshan controlled the software to let the three-dimensional Helmholtz coil create a new magnetic field, which exactly offset the external magnetic field, reducing the magnetic induction intensity in the entire measurement space to 0.

Judging from the data displayed in the software, the magnetic field strength in the measured space is now lower than 10^(-10)T.

This kind of shielding effect on the magnetic field is far better than the previous magnetic field shielding device handmade by Ning Chen and Qi Wan.

"Because various external magnetic fields, including the geomagnetic field, do not remain static at all times, but will always change dynamically, so our simulated magnetic field will also change dynamically, so that the magnetic field in the test space will always be 0 .”

After solving the problem of magnetic field shielding, the three began to measure the superconducting properties of topological superconductors.

Soon, Ning Chen controlled the ambient temperature to drop to near the superconducting critical temperature of the topological superconductor, and the zero-voltage conductivity peak also appeared on the screen.

Ning Chen very keenly discovered that the zero-voltage conductivity peak measured at the same temperature this time was more obvious than the previous measurement.

Ren Mingshan also witnessed such a measurement phenomenon for the first time, which showed that they were indeed on the right track.

After a whole day of experiments, the three of them completed the testing of multiple sets of experimental data.

After subsequent data analysis, they also found that after using a three-dimensional Helmholtz coil for magnetic field shielding, the measured zero-voltage conductance peak did become more obvious.

"What an incredible measurement result... Such a result basically shows that the observed zero-voltage conductance peaks are the experimental signals of the Andreev bound state!"

At this time, Ren Mingshan could not hide his excitement, because this was a powerful proof of the existence of Majorana fermions.

If we say that the previous experiments done by Ning Chen and Qi Wan still had some accidents.

Today's experiment has greatly reduced this chance.

……

In the following days, Ren Mingshan, Ning Chen, Qi Wan and others continued to measure other types of topological superconductors.

After using the three-dimensional Helmholtz coil device, almost every topological superconductor can measure a relatively obvious zero-voltage conductance peak.

Because in previous experiments, such an obvious zero-voltage conductance peak has never been measured in a topological superconductor.

Ren Mingshan is very optimistic that the experiments they have conducted are the closest that humans have come to Majorana fermions.

(End of this chapter)