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  • Dutch quantum leap for quantum computers

    - A team of researchers at TU Delft discovered the Majorana fermion in a major breakthrough for quantum computers. ScienceGuide talked with Vincent Mourik who was part of Leo Kouwenhoven’s team making what is deemed a Nobel prize worthy discovery.

    A little over a month ago, science media all over the world were hailing Leo Kouwenhoven's discovery of the Majorana fermion particle. Now, the work of his team was published in Science Express.

    ScienceGuide talked to doctoral candidate Vincent Mourik who was part of the researcher group that made this major breakthrough. Mourik explains his fascination for the Majorana quest, what challenges his team faced along the way and what this discovery could mean for quantum computers.

    Pure curiosity

    You and your team are investigating Majorana fermions. Why is that?

    It all starts with curiosity. Finding and understanding this yet unknown particle is really something new. It has characteristics which have never been observed before. That is why I dare to say that its discovery might be truly revolutionary.

    So what you are saying is that you were trying to discover it simply because you can.

    Fundamentally yes. You know for years nothing much happened in this field of science. We were looking for the Majorana fermion and what drove us was scientific interest as an end to itself.

    How did you start your search for this rare particle?

    I was studying technical natural sciences in Delft and through my final university project I got in touch with the research group surrounding Professor Leo Kouwenhoven. His team was part of the Kavli Institute of Nanoscience, a very prestigious organization. That was around two years ago.

    Back then, the whole idea of looking for the Majorana fermion was just at its beginning. Leo and his postdoc were contemplating ways of tackling this quest. They concluded that they could do this right here at Delft University. At that point in time, I was still looking for a topic I would focus on for my PhD thesis. I took the chance and joined their team which was quite a fortunate decision as it appears now.

    Synthesize or collide?

    So how did you ultimately go about the search?

    Basically what we did is that we created these particles ourselves by combining a number of ingredients. Of course there are a lot of theoretically appealing ways of detecting these kind of particles. Our goal, however, was to go beyond these theoretical concepts and make our search concrete. The know-how for this was right there in our team. We translated that into a practical experiment.

    Science media all over the world are hailing what they describe as an "incredible" approach to realize a major breakthrough. What was unique about your work?

    Well, if you consider that it took us only two years to detect such a fascinating particle, it is quite exceptional what we achieved. All we used was one tiny computer chip at little cost. I guess that really distinguishes ourselves from others.

    At CERN for instance experiments are conducted at a much greater scale. The people working there do an amazing job. Their approach is different, however. They are trying to detect particles by letting them collide with one another. By contrast, we were acting more like 'engineers' creating a system instead of only measuring results of a collision.

    Breakthrough for quantum computers

    What do you believe will the impact be of your discovery?

    Our ultimate goal here at the Kavli Inistitute is still the creation of a quantum computer. We want to build a computing system that works based on the smallest particles you could think of. Majorana fermions are of great interest in this context. What we discovered can become a key component of future quantum computers.

    Theoretically, research has shown that it is possible to build nano-sized computers. But they are very vulnerable to interferences from their environment. This would not be the case if you employ quantum bits with Majorana fermions. We believe that these are much more robust.

    This is really important. Since these fermions are much more stable you can use them to create hard disks for quantum computers. That is also why Microsoft is very interested in the research we are doing.

    Because of these unique features, scientists all over the world were looking for the Majorana Fermion. The very elite of our discipline was put to the task. That means we are talking about 50 teams all over the world working on this, from Harvard to ETH Zurich, from MIT to Chinese institutes. We hope that this competition is over now. Everybody know that our quest to find the Majorana Fermion was successful. And it was our team in Delft that made it.

    Nobel prize candidate

    Two years you were working heavily on this project. Was there also a moment when you starting doubting the success of your mission?

    For the past two years we were extremely busy. But of course there was also a phase when we made no progress. We needed a certain new material to conduct our experiment. It was made of nano wires and our colleagues at Eindhoven University were particularly skilled at working with it. We had to combine this material with a superconductor. That turned out to be a very challenging task and for three months we really got stuck.

    Twenty, maybe thirty times we tried to combine those parts without success. Every time we failed we had to see again what went wrong. But then after a lot of attempts it finally worked...

    There is a rumor among the Dutch technical universities that this discovery might be Nobel prize worthy.

    Well, this depends. The real question is what we do with this discovery. Majorana particles have a similar potential like graphene. Everybody understands that. What is important to see is that Andre Geim did not only discover graphene, but he worked intensively on follow up research showing its potential. That is really smart.

    So we cannot just leave the discovery of the Majorana fermion as it is right now. Instead, we have to look for real world applications and see what else we can find out about its characteristics. What can we do with it, that's the real question, isn't it? If we manage to build on this, the basis for future quantum computers may be laid out right now.

    If you would like to have a look at the data underlying the experiment, click here. For a complete press release by TU Delft, click here.