One of the most important technological developments at the moment is the search for the quantum computer. He doesn’t exist yet, but we’re getting closer. Professor Leo Kouwenhoven (54) from TU Delft is working hard on it and is giving us a lecture.
Leo Kouwenhoven: “Current computers can handle many problems. Looking up something on the internet or sending an email: that’s all fine. But there are problems that today’s computers cannot solve. Such as searching for the ideal medicine that works perfectly for one specific patient. That is never possible with an ordinary computer; it would take forever to do that. A quantum computer will do just fine. Such a quantum computer is a computer that calculates in a completely new way. As the name suggests, we are talking about a machine based on principles from quantum mechanics. That’s the theory we use to describe how small particles behave. Particles that are so small that they cannot even be seen with a microscope, but that are the building blocks of everything around us.”
“In that world of the tiniest things, very different things are possible than in our daily lives. For example, we cannot possibly be in two places at the same time, but super small particles can. In those two places they can also experience two different things at the same time. The quantum computer makes clever use of that fact. This means that it does not have to try everything one by one, like a normal computer, but can view several options at the same time.
Suppose, for example, that a postman wants to determine the ideal route for delivering his packages. An ordinary computer then has to go through all possible routes one by one, which quickly gets out of hand with a large number of addresses. However, a quantum computer can look at all possible routes at once and therefore quickly find the best option.”
”We transfer money via the internet, check in with the OV chip card and our smartphone is in fact a pocket computer. All this technology works on the same principle. The bank transfers, train journeys and apps are processed digitally. This means that the information is translated into mini switches that are ‘on’ or ‘off’, also called bits. The quantum computer will work with qubits, a completely different technology.”
Special particles
“A quantum computer like this doesn’t really exist yet. However, hard work is being done in all kinds of places, including in Delft. This largely revolves around the so-called quantum bits or qubits. You can see these as the ‘quantum variant’ of the digital bits in which an ordinary computer stores its data and does its calculations. You can make such qubits from majorana particles, for example. These are very special particles that my research group was the first to create in 2012, together with materials scientists from Eindhoven University of Technology. When we made those marjoram particles, Microsoft knocked on our door. The company wanted its own lab on the TU Delft campus to work on a quantum computer that uses majorana qubits. I then became the director of that lab.”
“Now we are busy actually making those majorana qubits. We just don’t know exactly how to do that yet. That is not so strange. After all, we are talking about particles that we only discovered a few years ago, and we already want to put them in a computer. Work on the quantum computer is currently gaining momentum. There are many companies that invest heavily in the field; not only Microsoft, but also IBM, Google and Intel. However, it is important to keep the following in mind. Building a quantum computer can be compared to crossing an ocean. The current rapids help us a little further, but we will still need about thirty rapids to really reach the other side.
Furthermore, different parties are now trying in different ways to get to the other side. Our qubits – based on majorana particles – are still under development. Other parties have already managed to make qubits in other ways. But majorana qubits are expected to be much more reliable than those other qubits. So once we have them, we can also build a quantum computer much better with them.
Currently, companies such as IBM and Google have already built quantum computers with a few dozen qubits. Unfortunately, a really useful quantum computer needs a thousand qubits. Making so many qubits work together in one computer is not that simple yet, but we think that in 2020 we can show that this is in principle possible. It will then take a few more years before we actually have such a quantum computer with a thousand qubits.”
No home computer
“It is important to realize that such a quantum computer will probably not be installed in your home. That would also be tricky, since current qubits only work well at very low temperatures, near absolute zero of -273.15 C. Errors may occur at higher temperatures. I expect that large data centers, which are now full of ordinary computers, will put a number of quantum computers in between. For the user at home, the switch will be relatively silent. He will only notice that certain things suddenly go much faster. Or that the computer can solve a problem it couldn’t solve before.
There is also a downside to these developments. The ways to encrypt data that we currently use can be hacked with a quantum computer. So in due course we will have to adopt a new way to protect our data. All confidential internet traffic, from WhatsApp messages to PIN codes, must then be encrypted differently. But the home user probably doesn’t have to do anything for that. That is a job for banks and companies. Anyway, this isn’t a huge problem.
As far as I’m concerned, it doesn’t outweigh all the good we can do with the quantum computer in the future, for example for the environment. And if the quantum computer can help to calculate the medicine that works best for each individual, for example against diseases such as Alzheimer’s or Parkinson’s, that would of course be very nice. Although you should not think: once that quantum computer is there, I will be cured the next day.”
What is already known & what is not yet?
KNOWN
- We have been able to make quantum bits or qubits since the early 2000s: the bits that a quantum computer uses for calculations.
- In 2012, professor Leo Kouwenhoven and his colleagues at TU Delft were the first to make majorana particles. Hopefully, extra reliable qubits can be made with this.
UNKNOWN
- It is not yet clear how we should make qubits from majorana particles. Leo Kouwenhoven’s team is busy with this.
- There are currently quantum computers with a few tens of qubits, but a full-fledged quantum computer will need around a thousand qubits.
Knowing more?
In the booklet The quantum computer. A digital revolution on the brink of breaking out from science journalist George van Hal you can read more about the supercomputer