A Flash of Inspiration
for the Quantum Age

Impact Story

Controlling large quantum computing systems presents developers with major technical challenges. As part of his basic research funded by the Austrian Science Fund (FWF), the Tyrolean quantum researcher Wolfgang Lechner came up with the idea of a new type of architecture for quantum computers, in which the complex networking of many qubits – a frequent stumbling block in quantum computing – becomes a thing of the past. The spin-off company ParityQC, where Lechner and his team are applying the technology, has rapidly become a success story.

Sometimes the best ideas strike you when you least expect them: Wolfgang Lechner, for example, woke up in his hotel bed in the middle of the night during a conference visit to Denmark and had a flash of inspiration. The quantum physicist from Innsbruck suddenly knew how a revolutionary architecture for quantum computers could finally be achieved. An approach that had already been mathematically falsified by Lechner himself, among others, suddenly became mathematically possible in its modified form. The late-night flash of inspiration led to a patent and a few years later, in 2020, to the founding of ParityQC, a spin-off of the University of Innsbruck and the Austrian Academy of Sciences (ÖAW). The aim is to rethink quantum computing and, in doing so, solve major problems faced by previous architectures, which become difficult to control with increasing size.

Five years later, the Innsbruck-based company, including its subsidiary in Berlin, already has 60 employees, and a further branch in London is currently in the works. Lechner and his colleagues were able to convince hardware manufacturers all over the world of their novel quantum computer blueprint, which can handle even large computing tasks without reaching the limits of complexity. One of the first major collaborations was with the Japanese IT group NEC, which is now fully committed to the approach from Innsbruck. In 2023, NEC presented the world's first quantum processor with ParityQC architecture. 

Lechner’s start-up has an excellent network in international quantum research: Together with a consortium, they managed to secure two of the largest contracts that the German Aerospace Center (DLR) has ever awarded in the field of quantum computing. The company is represented in a total of twelve international research consortia. To date, ParityQC is the only company of its kind in the world offering a quantum architecture – i.e., a specific way of implementing quantum computers – on a commercial and licensed basis. “Thanks to our business model, we can work with partners globally and still keep the added value in Europe,” says Lechner. The quantum start-up, which he runs together with co-CEO Magdalena Hauser, has been in the black since 2023.

In a nutshell

Wolfgang Lechner’s research work focuses on novel blueprints for quantum computers that are easier to implement for large computing tasks than previous approaches. Instead of coupling many qubits, the smallest information carriers in quantum computers, their mathematically described interactions are used to perform calculations on a quantum mechanical basis. This means that complex calculations can be realized with significantly less technical effort than with previous quantum computers. These novel quantum architectures are also the subject of the spin-off ParityQC. The company works with hardware developers worldwide to transfer the results of basic research into practical applications.

Magdalena Hauser and Wolfgang Lechner on red armchairs
Magdalena Hauser and Wolfgang Lechner have turned ParityQC into one of Europe’s most profitable quantum computer companies in just a few years. © ParityQC
Illustration of a chip architecture
The illustration shows a chip with the ParityQC architecture – based on research findings that also resulted from FWF-funded research projects.
© ParityQC

“Thanks to our business model, we can work with partners globally and still keep the added value in Europe”

Powerful quantum systems reach the limits of complexity

In principle, quantum computers work with qubits, i.e., the quantum mechanical counterparts to bits in digital computing systems. Unlike bits, however, they can not only assume the values zero or one, but also both states simultaneously thanks to quantum mechanical superposition. If a large number of qubits can be entangled in a controlled manner, a multitude of computations can take place simultaneously, allowing the performance of quantum computers to far exceed the potential of conventional systems. But the technology is not quite there yet. Qubits can be physically implemented in various ways – for example as superconducting systems with resistance-free currents, as ion traps holding particles in magnetic fields, or in photonic quantum systems using light particles as information carriers. But it’s still not possible to entangle enough qubits to solve large computing tasks in a targeted, controlled, and error-free manner. The technical complexity increases rapidly as the number of qubits increases and presents researchers with considerable hurdles. 

The quantum architecture that Lechner and his team at ParityQC are working on, however, avoids this problem in a very fundamental way. The focus is not on the number of qubits, but on the interactions between them. These interactions no longer have to be physically realized, but are instead described mathematically and translated into so-called parity conditions, or rules that can be implemented locally in the hardware. This means that the problem is put into a form in which no large number of qubits need to be controlled simultaneously. To put it very simply: The qubit is made to believe that it has complex interactions with other qubits, but these do not actually have to take place physically. 

Even before that fateful night in Denmark, Lechner, together with his Innsbruck colleagues Philipp Hauke and Peter Zoller, was pursuing a similar approach to physically describe qubit interactions. However, a mathematical proof to the contrary put an end to this approach for the time being. His brainwave was finally the “brilliant idea of how to arrange the qubits in order to get a consistent result after all. So the original mathematical proof was not as general as I had thought,” the quantum researcher described his breakthrough in an interview with the daily newspaper Der Standard.

Short bio

Wolfgang Lechner is a professor at the Department of Theoretical Physics at the University of Innsbruck and co-CEO of the company ParityQC. After studying physics at the University of Vienna, his postdoctoral phase took him to the University of Amsterdam and the Institute for Quantum Optics and Quantum Information (IQOQI) in Innsbruck. From 2013 to 2016, he headed the research project “Ultracold Atoms and Molecules: From Defect Dynamics to Quantum Glass,” funded by the Austrian Science Fund (FWF). From 2017, he established a research group with funding from an FWF START Award. He was appointed as a professor at the Institute of Theoretical Physics at the University of Innsbruck in 2020. In the same year, he founded the university spin-off ParityQC, which is turning one of Lechner’s research findings into a commercial application with a novel system architecture for quantum computers.

NEC-Forscher:innen arbeiten am Bau eines Quanten-Annealing-Gerätes
The Japanese IT group NEC relies on the quantum computer blueprint developed by the Innsbruck-based researchers. Here, NEC researchers are building a next-generation quantum annealing device. © NEC Coporation

Following up on ideas from basic research

At the time, Lechner was still researching ultracold atoms and molecules at the Institute for Quantum Optics and Quantum Information (IQOQI) in Innsbruck as part of a project funded by the Austrian Science Fund (FWF) – a topic that had little to do with quantum computers. But in basic research, you are well advised to pursue any good ideas, no matter where they lead. So Lechner pursued his alternative quantum computer approach, published his results, and finally applied for a patent, which also made waves. Among other things, a US company offered to buy the patent rights. The researcher wanted to further develop the technology himself, however, and from 2017 he was able to devote himself fully to this plan. His research was honored with a highly endowed FWF START Award. In the project “ParityQC: Parity Constraints as a Quantum Computing Toolbox,” he was able to develop the foundations of the new quantum computing concept with his own team.

Lechner’s approach was originally developed in the context of quantum annealing – a special type of quantum computing that is limited to solving optimization tasks. This makes use of the phenomenon that a quantum system automatically strives for a state with the lowest energy under certain conditions. This means that qubits are always looking for an energetic optimum for themselves, and this process can be linked to the search for an optimum solution in a calculation problem. The first chip with ParityQC architecture – the one from NEC from 2023 – is an 8-bit quantum annealer that can be controlled via a cloud application. 

But the annealing variant was just the first step. Lechner and his team are convinced that universal quantum computers can also be created based on the ParityQC approach – i.e., the type of computer that is currently based on many entangled qubits and can implement various types of quantum algorithms. Research collaborations with hardware manufacturers are already in place, and the technology could be ready for practical use in just a few years’ time. The potential is enormous. If fully utilized, ParityQC could play a key role in the European and global implementation of quantum computing.

Exploiting the economic opportunities of quantum science

The ParityQC quantum architecture success story is an example of how close basic research and commercial viability can be in the disruptive environment of quantum science. The rapid development of the approach, which has emerged entirely from basic research projects, is an example of the economic potential of quantum science in Austria – a country that is traditionally strong in this field of research and has already produced several Nobel laureates, from Erwin Schrödinger to Anton Zeilinger. A recent Cluster of Excellence funded by the Austrian Science Fund (FWF), Quantum Science Austria, is currently continuing this tradition. 

Strengthening the domestic quantum science ecosystem makes the technology sector more visible, keeps highly talented researchers in the country, and attracts new ones. At the same time, it revs up the performance of the innovation engine that drives the economy in Austria, an industrialized country characterized by high-tech. But there is still a lot to do. “The main danger is that a lot of development will take place in Europe, but the added value will be created elsewhere,” Lechner explains in Der Standard. He calls for strategies to keep the development and commercialization of products and applications as well as excellent basic research in Europe, and his company ParityQC is an excellent demonstration of how to do it.

(Video credit: ParityQC: Sie arbeiten am massentauglichen Quantencomputer!, FFG)

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