Quantum certainty: delivering on the QuTech promise

It all started as a rather theoretical concept: use some of the more intricate properties of quantum mechanics, the physics of the ultrasmall, to perform certain calculations. You could also transfer information in a fundamentally unbreakable way. Where our every-day computers use bits - units of information that can be 1 or 0 - quantum computing uses quantum bits (‘qubits’), which can be any combination of 1 and 0. Such a qubit could consist of a single elementary particle with the ability to exist in multiple states at the same time. In quantum mechanics, this ability is called a superposition.  

Inspired by this possibility, physicists started finding several qubit candidates: physical systems that can preserve and manipulate such a quantum mechanical state, which is typically extremely fragile (see fold-out The undecided qubit race below).

The quantum revolution 

After theoretical physicists and mathematicians explored these concepts in the early 2000s, a quantum revolution became imminent. Enticed by applications that no other technology promises, large universities and companies such as IBM, Google, Intel, Microsoft and Fujitsu started working on quantum computers. Two applications loom large in the future of quantum technology. One is the famed quantum computer, which can perform certain specific calculations immeasurably faster than any normal computer could ever hope to achieve.

‘For example, take calculations relating to the structure of molecules and materials’, says Vandersypen. ‘Their behaviour is determined by the behaviour of atoms and electrons, which is inherently quantum mechanics. Imagine designing batteries that are so powerful you only have to charge your phone once a week or making electric cars with enough range to drive from the Netherlands to the south of France on one charge. Or think about more efficient chemical plants, developing drugs to treat incurable diseases, and optimised fertilisers that help to feed us but have less impact on the environment.’ 

To predict how this future will  become a reality, is notoriously difficult, he admits, ‘This is the one application that would have very broad use, but I expect it to be around ten years away at least.’ 

QuTech 

Another important quantum technology is quantum communication, a form of secure communication that is fundamentally impossible to eavesdrop on. Vandersypen: ‘The quantum nature of the connections and nodes will make any interception inherently detectable.’ 

As research at TU Delft delivered more quantum breakthroughs, QuTech was launched in 2015 with a vision to make the Netherlands a hub for quantum technology. ‘Quantum computing comprises about two-thirds of QuTech research, quantum internet about one-third’, says Vandersypen.

‘QuTech is unique in its broad, horizontal research strategy’, says Kees Eijkel, QuTech’s director of Business Development. ’We don’t know which qubit candidate will turn out to be the most useful for building quantum technology, and there may even be several. Where many parties choose a vertical approach, e.g. one type of qubit, one type of computer, we’re saying that there are several options at every level. We keep working on the options that we believe are still in the race to win.’ 

‘Apart from the type of qubit, there is a lot of focus on the number of qubits’, says Lieven Vandersypen. News headlines tout claims of quantum computers comprising ever higher numbers of qubits, with IBM announcing a 433 qubit computer last May. ‘But many other factors come into play’, says Vandersypen. ‘For example, how well you’re able to control your qubits - i.e. the fidelity - is important.’ The quantum information encoded in qubits is inherently fragile. They need to be protected and made to interact with other qubits in precise ways to build quantum applications.  

A third factor is connectivity: the number of links each qubit can make. Vandersypen: ‘In an ideal world, each qubit could talk to every other qubit. In practice, the qubits can often only talk to their direct neighbours. 

Unique Delft approach 

While QuTech scientists are working hard to increase these numbers, they concern only the core of any quantum system, which requires many other parts: from ultra-precise electronics to exert control and read out qubits to cabling that can transmit quantum information. And from reliable photon detectors to refrigerator systems that deliver the required temperatures of just above the absolute minimum of -273 degrees Celsius.

QuTech’s approach to this is also unique. ‘QuTech is very focused on developing the full system, the full stack as we say’, says Vandersypen. Where players like IBM and Google choose to develop this full stack in-house, QuTech focuses on fostering an ecosystem of research groups and companies developing individual parts.

For example, the quantum startup Q*bird is working on quantum key distribution, a vital ingredient of secure quantum networks. Another startup, Quantware, builds quantum chips, while Orange Quantum Systems develops software to calibrate quantum systems, and the startup Qphox is working on interconnects, which can transfer quantum information optically. There is a university spin-out, Single Quantum, developing superconducting nanowire devices that can reliably detect single photons or light particles.

House of Quantum

Many startups are housed in the House of Quantum incubator centre in Delft. ‘There is a lot of collaboration and discussion, and we do collaborate on development projects to match each other’s technology’, says Niels Bultink, CEO of Qblox, a scale-up company that develops, builds and sells control electronics.

‘As a PhD student in Delft, I did experiments on error correction, a way to combine several qubits to make a single, more reliable qubit. To do this, I needed special equipment that was being developed by TNO’, says Bultink. Halfway through the PhD project, we realised: ’We can make a company out of this.’

Five years ago, the control electronics of the quantum chips were quite complicated: ‘We used a lot of standard lab equipment such as wave generators and oscilloscopes, and we built the control system piecewise. That’s how university research works. But scaling-up things is an expensive and slow way to work, which is prone to errors.’

So Qblox designed and built dedicated, scalable electronics that combine all functions with one miniaturised, modular system that can control 20 qubits with picosecond precision. This makes things much more scalable and ready for larger quantum chips. ‘We now have 85 people working here’, says Bultink, ‘and more than 100 systems ordered. We have even been able to turn a profit in our first years. I suppose we are no longer a start-up but a scale-up.’

Fujitsu 

QuTech also cooperates with major companies like Intel, Microsoft and recently the Japanese company Fujitsu (see fold-out below). ‘Collaborations like these are extremely important. QuTech is about building options for a scalable quantum system’, says Kees Eijkel. ‘A working experiment in a lab, created by university researchers, is only the first step. Ultimately, you will have to make ten, a hundred, a thousand of them, in a reliable and, ultimately, cost-efficient manner.’

QuTech deploys demonstrator projects to bridge fundamental research and commercial activity in companies. These projects are full stack functional systems to showcase Quantum Technology. One such demonstrator is Quantum Inspire, an online interface that anyone can use to test a real 5-qubit quantum system functioning in Delft. Another demonstration project is the star-shaped quantum internet that Q*bird has set up in the Rotterdam harbour to showcase inherently safe quantum communication. 

Helping society 

This involvement, says Vandersypen, goes both ways. ‘We don’t do this for ourselves. Science is meant to help society with applications, but we also feel the duty to inform society about those applications. Quantum technology is a new technology, and new technologies always have unexpected consequences, some good and some potentially dangerous. This is where we want to assume responsibility and be part of the discussion.’