Not so very long ago, quantum mechanics was a playground for fundamental physics research only. Now, with the first quantum computers and the quantum internet, we are about to enter the era of real-world applications. A look at the current status and the important role of Leiden and Delft in ongoing developments.
On the scale of molecules and atoms, the world is governed by the laws of quantum mechanics - laws that defy our everyday experience. A single electron can occupy two quantum states at the same time (‘spin up’ = 1, en ‘spin down’ = 0) thereby defining a qubit, the basic building block of all quantum technology. This is as opposed to the bit of a classical computer that either has the value one or zero.
It is the ability to entangle multiple qubits that gives quantum technology its real power. One of the consequences is that the computational power of a quantum computer doubles with every qubit added – quickly dwarfing the largest supercomputers for certain computational tasks. Entanglement also allows for the 100% secure exchange of information between nodes of the quantum internet.
We are optimistic that we may have a fully functioning quantum computer in a decade from now' - Carlo Beenakker
Scaling up and a killer-app
The leap from the research laboratory to preliminary real-world applications is driven by the ever-increasing mastery of qubits, and by the insight that quantum technology can be used to address meaningful problems – in, for example, the fields of energy, food production, drug development and cybersecurity. But we’re not there yet. ‘It is a major practical challenge to minimise outside disturbances. These can lead to qubits losing their quantum information before a quantum calculation has been completed,’ says Lieven Vandersypen, research director at QuTech and professor of quantum nanoscience at TU Delft. ‘It requires a large overhead to correct for such disturbances. We, therefore, have to scale-up to a quantum computer running on millions rather than thousands of qubits.’ But even with such upscaling, we’re not there yet. ‘We don’t yet have a clear route towards actual applications,’ says Carlo Beenakker, professor of theoretical physics at Leiden University. ‘Quantum technology may well be a gamechanger, but it is still possible that it will not be able to meet the sky-high expectations. Someone has to come up with the so-called killer-app, the equivalent of Google and Facebook for our current computers and the internet.’
A long tradition in quantum research
‘At Leiden University, research into physics at the scale of atoms – nanophysics – started when the Lorentz Institute was founded, now exactly a century ago,’ Beenakker says. ‘Over time, this research into atoms and molecules morphed into quantum research. We recently launched AQA (Applied Quantum Algorithms), pooling all ongoing efforts towards quantum technology within physics and computer science. AQA is our platform for collaborating with industry.’
At TU Delft, research towards understanding and controlling quantum mechanical effects started in the ‘80s, on chips quite like those used in normal computers. ‘In 2014, together with TNO, we launched QuTech,’ Vandersypen says. ‘We had to find a new way to make big steps, to stay at the forefront of quantum technology. Next to PhD students and postdocs, we have an increasing number of researchers for whom scientific output is not the primary concern. This allows them to approach practical issues with an engineering mindset.’ QuTech also incorporates various disciplines – physics, electrical engineering, informatics and, as of recently, even industrial design. These latter researchers address the user experience of upcoming quantum technology.
A comprehensive approach, all the way to your lap
Leiden and Delft have secured many large grants and subsidies during their decades-long research collaboration. And, at the beginning of this century, the two universities founded the Casimir Research School, aimed at providing full-spectrum education into nanoscience to both master students and PhD students. A combined master in quantum technology is in the pipeline. A recent feat was to obtain an NWA-subsidy (Dutch Research Agenda), together with another twelve knowledge institutions. The aim of the project is to bridge the gap between up-and-coming quantum technology and its future users, such as industry and schools. Central to this aim is Quantum Inspire, the first European online quantum computer. As of April 2020, it is possible to control its two kinds of qubits from the comfort of your home.
A perfect match
‘It has been TNO that put the most effort into translating the many physics lab experiments into the Quantum Inspire demonstrator that is available 24/7,’ says Vandersypen. ‘It is also a full system test; from the quantum chip to the classical electronics controlling this chip, to the computer architecture on top of that.’ Whereas the mission of QuTech is to develop scalable prototypes – all the required hardware – of quantum computers and the quantum internet, Leiden focuses on how to use this technology. ‘It is one thing to build a quantum computer, another thing to program it,’ Beenakker says. ‘Within AQA, we develop algorithms for tomorrow’s quantum computer, so that it can be used for solving practical problems in the realm of physics, chemistry and informatics.’
No colony on Mars, but the quantum computer can take off
Naar verwachting zal QuTech begin volgend jaar ook een demonstrator van het quantuminternet online zetten, genaamd Quantum Link. Daarnaast is het Quantum Inspire platform in continue ontwikkeling waardoor nog weer complexere algoritmes en toepassingen getest zullen kunnen worden. Zo staat quantumtechnologie, ook in Europa, op de drempel van maatschappelijke toepasbaarheid en durven bedrijven erin te investeren. ‘We zijn optimistisch dat we in vijf tot tien jaar een volwaardige quantumcomputer hebben,’ zegt Beenakker. ‘Begin deze eeuw was de verwachting dat het nog vijftig jaar zou duren, dat is dus veranderd! Een kolonie op mars is deze eeuw niet haalbaar, maar met de quantumcomputer en het quantuminternet kan het heel snel gaan.’ Met dank dus aan fundamenteel onderzoek en ontwikkeling in Leiden en Delft.
Carlo Beenakker is professor in de theoretische natuurkunde aan Universiteit Leiden en gespecialiseerd in de nanofysica, waarbij atomen en moleculen zich gedragen volgens de wetten van de quantumwereld. Eind jaren ’80, toen quantumtechnologie net in opkomst was, werkte hij vanuit het toenmalige Philips NatLab al samen met de TU Delft.
Lieven Vandersypen is professor in de quantum-nanowetenschappen aan de TU Delft en wetenschappelijk directeur van QuTech. Als zestienjarige raakte hij dankzij populairwetenschappelijke boeken gefascineerd door de quantummechanica. Als promovendus, en ook daarna, was hij verantwoordelijk voor enkele mijlpalen op het gebied van quantum computing, waaronder het daadwerkelijk ten uitvoer brengen van quantumalgoritmes.