Pablo Jarillo-Herrero Photo: Li Qiaoyi/GT
The physics world was last year stirred up by the findings of a research team at the Massachusetts Institute of Technology (MIT), which recorded the superconductivity of magic-angle twisted sheets of graphene at 1.7 kelvin (-271.45 C). China has made a hefty commitment to the super-material of strategic significance for technological innovation. The country has been particularly thrilled about the giant leap as 1996-born Cao Yuan, a graduate from the University of Science and Technology of China and a doctoral candidate in physics under MIT professor of physics Pablo Jarillo-Herrero (PJH), is a crucial member of the team led by Jarillo-Herrero. Cao discovered the magic angle and published two papers in the prestigious Nature magazine as first author in March 2018.
Cao enjoys being at MIT and, once he graduates, he has to make his decision about what to do, Jarillo-Herrero revealed in an exclusive interview with Global Times reporter Li Qiaoyi (GT) in Beijing, on the sidelines of the Future Science Prize Forum earlier in November. Jarillo-Herrero also touched on some vital aspects of graphene research and commercialization, China’s technological rise and the resulting unease in the US.
GT: Will graphene be made to superconduct at room temperature? If possible, when will that happen?
PJH: It’s really hard to tell. Right now, graphene superconducts only at low temperatures. There are some physicists that think it is possible to make graphite – all combinations of graphene sheets – superconduct at room temperature. But I think, honestly, it will be quite hard in the case of monolayer graphene, because the charge density one needs to have in order to have a room-temperature superconductor is typically very high. So I think it will be hard to do that, at least in the present material variations. I want to be optimistic. We can go to substantially high temperatures, but room temperature is very difficult.
Right now, the maximum temperature for our devices is 3 kelvin. Room temperature is 300 kelvin. We have to go (up by) a factor of 100. I can imagine going up by a factor of 10. A factor of 100 will be very difficult.
GT: Is China leading the global graphene sphere in terms of research and development (R&D) and commercialization?
PJH: China has invested many resources into graphene and two-dimensional materials. I know here in Beijing there’s a very well-known graphene institute. I’m very impressed with the way China is approaching research in materials science, its investment in basic science and also in applications. There are many other countries that have also invested in materials. I’m not sure one can say that China is leading. It’s certainly one of the leaders (among countries) that invest heavily in graphene R&D.
Commercialization is still a little bit lacking, not only in China, but every country, because we’re still figuring out the most important applications for graphene. We have to see. There are already some prototypes, but we need more basic research.
Definitely, the electronic, optical and mechanical properties of graphene are extraordinary. Now, when a material has extraordinary properties, it means there’s a very good chance that we will be able to make use of (them) to come up with new applications.
Some people think we should be using graphene for old applications. I think that’s probably not the best use of graphene because we already have other materials like silicon which are very good at what they do.
The best applications for graphene are those where we do not have existing materials.
So I prefer to think of graphene for new applications rather than for better applications of the old. Graphene is only one atom thick. It’s very strong but also very flexible, similar to bed sheets. It’s very hard to break, easily folded. It can be folded and it conducts electricity very well. It also has optical properties, so you can imagine integrating graphene, for example, into fabric and foldable clothes. That’s something that’s not easy to do with silicon, because silicon doesn’t bend. But graphene can bend easily. So maybe you can use graphene and other two-dimensional materials to integrate electronics into fabric and clothes. That’s just one example. There are many such examples.
But of course we don’t yet have electronic clothes, so this has to be completely new. I don’t think there is any fundamental reason that we cannot do it, but a lot of research has to be done because it’s a completely new technology.
GT: What do you think about the announcement from Chinese scientists in September, that they have developed an atomic-level graphene-folding technique? How disruptive is the method?
PJH: This method of folding graphene that was developed here in China, I think is very interesting. These researchers were able to fold graphene along different directions.
One thing my group contributed last year was the discovery of (what) happens when you put two graphene sheets on top of each other. One way of putting two graphene sheets on top of each other is to fold them, so I was very interested and I think it’s a very interesting basic research piece.
Now, the method the researchers use (currently) has to be done one device at a time. That’s very good for physics experiments, like the ones I do, but if you want that to have an impact on technology, you need to develop a scalable process – a process that you can do in parallel with many graphene devices. And I think a lot more research needs to be done so we can do this in parallel, reproducibly, always having the same outcome. Then there is a chance that scalable technology could be used for many applications.
GT: To what extent have US scientists and researchers collaborated in the graphene field? Has bilateral collaboration been affected by the trade woes between the two countries?
PJH: In the US, we have benefited enormously from having many talented Chinese students who have come to the US to do their PhDs and post-doctorates. One example is Cao Yuan. He went to the US, joined my group and contributed decisively. He is the first author of the papers where we made our groundbreaking discoveries. I’m extremely happy and have a lot of Chinese students in my group, because I think China has tremendous potential as the population is so large. The contribution China has made to science (by) sending many talented students to the US, Europe and many other places has been tremendous. China, over the past two decades, has grown enormously itself in terms of science, and I think it’s doing very well. I remember 15 or 20 years ago, when I was doing my PhD, I would not normally read Chinese papers to be honest. It didn’t happen. Now I read a Chinese paper every week. Part of it has to do with investment in the education of young people. There’s been some collaboration between Chinese scientists and US scientists, European and Japanese. I’m a little bit worried that now some of these collaborations are a bit more difficult because of global geopolitical tensions. I think that the potential China has is enormous and it’s developing very fast.
It’s true that nowadays, some Chinese scientists and students (find it difficult) to get their visas, to travel to the US, to participate in conferences or to go to the US for graduate school. I think that’s a shame. I hope that the visa review process, while thorough, can be done faster. Science is a very open field. Scientific enterprise has always been something that unites countries, because people speak the same language of science, physics and mathematics, and I think that’ll be very good, to keep a very open atmosphere in science.
GT: When will graphene chips become a reality? If materialized, will China grow as a chip-making leader, factoring in its leading position in graphene?
PJH: That depends on what you mean by graphene chips. Large-area graphene-sheet wafers that can then be used for other applications – that’s already a reality. People are already able to buy graphene wafers. However, the quality has to improve. Now, if by graphene chips people mean micro-circuits that make use of graphene transistors, we are not there yet. But there are some interesting prototypes of graphene technologies. I’m already aware of some startups which have prototypes of graphene-based cameras, because graphene can detect light – visible light, infrared light, all kinds of light. There are some cameras which are based on graphene and infrared radiation that can penetrate through water and fog. These companies are trying to make graphene infrared cameras, so you can see when you drive through fog and rain, improve the safety of cars and see more easily at night. That’s a niche market. There are many such potential applications.
GT: What do you think about the potential of using graphene in quantum computers? Has the US achieved quantum supremacy?
PJH: Quantum computers are still in their infancy. They are only prototypes. Now, some of the most advanced prototypes use superconductors. Graphene is a superconductor as of last year. It’s not only a superconductor, it’s a superconducting transistor, because we can electronically control whether graphene can become a superconductor or not. The superconductors used in quantum computers are not superconducting transistors, they are just metallic superconductors. In that sense, graphene offers an advantage because you can tune it. The technology to make graphene superconducting devices is many years behind the technology (used) for quantum computers, so we have to do a lot of investment in basic research before we can think and apply that research.
In my group this year, in collaboration with other scientists in the US, we published the first graphene superconducting qubit, or quantum bit, which could possibly be used for quantum computers. In that qubit, (we still used) regular superconductors attached to graphene (instead of) superconducting graphene itself.
We’ve already demonstrated the elementary pieces (used) to make a quantum computer with a graphene-based device – the performance is just not as good as with other devices. This is very preliminary. We have to make much more investment in basic research to see if graphene can be used for this.
That quantum supremacy, it sounds cool, but I’m not sure it means a lot to be honest. I think the (US’) recent announcement of achieving quantum supremacy (involved) a very particular algorithm. I think there are still many years before quantum computers can reach a level where you can truly tell they can beat classical computers. We also don’t have too many algorithms where quantum computers are better than classic computers. There are only a few important ones. We are going to have classic computers computing for many, many decades to come. Slowly, quantum computers will make better contributions. Whether they will make massive use of computation, I don’t know. Maybe they’ll be restricted to very specific tasks, such as quantum simulation, chemistry, and perhaps a few algorithms where quantum computers do a very good job.
GT: How would you compare the Future Science Prize to the Nobel Prize? How big is the technological gap now between China and the US?
PJH: I know people call it the Chinese Nobel Prize. I don’t think it makes too much sense to try to compare them. But I think it’s important to see that the Future Science Prize is being awarded to scientists who have made tremendous contributions to science, and that the caliber of people receiving the prize (is the same as that of the) Nobel-prize-winning people. For the prize to have an impact, reputation and be taken seriously, they need to (carefully) choose who they award the prize to. And they have to be people that the scientific community respects.
It’s perfectly fine if you have a prize mainly given to scientists of Chinese origin, for contributions to research in China. Of course, if these prizes are going to have a different level of prestige and impact, it needs to be a truly international award. Worldwide, the pool of high-caliber scientists is larger. In that sense, because the Nobel Prize is given to scientists from any country in the world, it has been more prestigious.
I think there are areas where China is already doing as good as, or in some cases better than, the US. If you think (about) cutting-edge innovation, the US perhaps in some areas still has an edge because it has a longer tradition of risky projects and intellectual innovation. China has been extremely good at taking innovation, then doing R&D and starting companies and manufacturing.
China has excelled in terms of manufacturing and supply chains. It’s also playing an increasingly (important) role in intellectual innovation. It’s probably fair to say that cutting-edge innovations of basic science (are) still produced more in the US than in China. China has been catching up fast, because there is a lot of talent here. It’s not surprising.
Additionally, the US system has traditionally been effective in integrating basic science, funded by the government and private foundations. Lately, the US government (has not been) investing the necessary resources in basic science. By contrast, the Chinese government is doing very well in terms of investing in basic science, but its (private) investment may be lacking a little bit. We need to have both.
GT: Would you agree that a tech cold war has begun between China and the US?
PJH: I don’t like the word “war.” There are challenges there, which are largely a question of geopolitics. At the basic level of scientists, the relationship is very cordial as we are very open and look forward to discussions, meetings and very open exchanges. Technology companies at the moment are competing, they want to file patents and make money. I hope both countries will do their best to resolve their differences, because I think the world needs the US and China together, solving the many global challenges that mankind faces.
It would be good for the two countries to be friendly competitors. It’s always good to have a little bit of competition, because innovation happens when there’s competition, but it has to be friendly.
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