In part two of the interview marking the 100th anniversary of quantum mechanics, ETH Professor Klaus Ensslin explains why quantum technology is developing at such a rapid pace at the moment and why Switzerland needs to make an effort if it doesn't want to be left behind.
Given the pace of advances currently being made in quantum technology, looking ahead to the next hundred years is probably tough. But where will the technology be in ten years?
Klaus Ensslin: I think quantum technology will have become the norm in ten years. It will be part of our lives and part of our education. Only physicists learned about quantum mechanics in the beginning. Nowadays, it's become an integral part of the curriculum in the subjects of chemistry, electrical engineering, mechanical engineering and other engineering sciences. The quantum engineering degree programme is one of ETH Zurich's most successful programmes. Since ETH was the first university in the world to offer this degree programme, we were overrun with applicants at the start. Since then, every respectable university has added a quantum programme.
Why did it take so long for things to get off the ground in quantum mechanics?
Even if the physics questions are very old, engineering is what caused quantum mechanics to take off. Some call it the second quantum revolution. This vital leap - from physics to engineering - is something we've also seen in conventional mechanics. Isaac Newton made his discoveries way back in the 17th century. But a big leap was needed before we could use them to build a turbine or an aeroplane. Only now, one hundred years after the laws of quantum mechanics were first formulated, are we in a phase in which we're making fundamental advances to the technology.
About
Klaus Ensslin has been a Professor of Experimental Physics at the Laboratory for Solid State Physics at ETH Zurich for 30 years. He will also become President of the external page Swiss Quantum Commission on 1 January 2026.
Precisely where are we in this phase?
Quantum sensor companies and products already exist. We're still in the initial stages of quantum computing - where a few things already work but a lot of things still need to be improved. In the area of quantum cryptography, there are already large companies with more than 150 employees offering products you can buy.
Are any quantum companies already earning money?
Jonathan Home just recently started a spin-off. ZuriQ is one of the latest companies to come from academia and pursues an entirely new approach to building quantum computers. That's what makes this spin-off so impressive. And as a small Swiss company, it is also bold enough to enter the market. US companies like Google or IBM have an enormous budget and several hundred employees working in the field of quantum technology.
The first quantum companies were founded around ten or fifteen years ago. Some of them only just barely escaped bankruptcy and changed their product as a result, others were bought up. People are pinning a lot of hope on this new technology and expectations are probably also a bit too high in many cases, particularly when it comes to investors.
The situation surrounding the first computer companies was probably very similar back in the day, don't you think?
Yes. But back then, nobody knew what computers could do and nobody could imagine that each and every one of us would someday have a computer at home. But now we're all driven by the idea that we're living in an information society. It's a common belief that expanding our information society further is good and valuable. Quantum computers are an extremely important part of that, which is why there's so much euphoria surrounding them.
You were appointed Head of the National Centre of Competence in Research "Quantum Science and Technology" (NCCR QSIT), which comprises 30 Swiss research groups, in 2011. It came to an end, as planned, three years ago. Where does Switzerland currently stand by international comparison?
NCCR QSIT was important and helped Switzerland advance. Once it had ended, the Federal Council initiated the Swiss Quantum Initiative in 2022. This Swiss quantum programme has a budget of several tens of millions of Swiss francs. While that's a large amount for a dedicated research programme in Switzerland, considerably more is being invested internationally. By comparison: China's capital city of Beijing is investing 500 million dollars in quantum technology. Switzerland was one of the first countries to have a national quantum centre. Countless other countries now have one as well. Switzerland needs to make an effort if it doesn't want to be left behind.
What makes you say that?
I attended a quantum conference in Korea last summer that was organised by the Korean government. As in other Asian countries, quantum technologies are one of the Korean government's key objectives. The country is investing a great deal of money. Switzerland might still be ahead of Korea, but Korea will catch up at some point.
Switzerland's lead is disappearing even in Europe. Originally, those of us doing research at Swiss universities were associated with the European Quantum Technologies Flagship programme. We were excluded in 2021 in connection with the termination of the Horizon Europe programme. The EU built up a European quantum cryptography network without us. While researchers from Swiss universities are allowed to participate in the EU programme again, it's obvious that the European quantum programme has evolved in the meantime. We missed out on those years.
Does that hurt personally?
Yes. I think it's a pity that Switzerland was excluded, and it's also a pity for the EU. They removed three strong quantum countries - Switzerland as well as the UK and Israel - from the programme. Things are now back on track, however.
Regardless of the collaboration with the EU, do you believe that the Swiss government is doing too little for quantum technology?
Yes. On the one hand, we started everything at such an early stage in Switzerland because everything works from the bottom up here. The way I see it, though, we should now start approaching some issues from the top down.
Which issues, for example?
There were a few key moments when it would have been important for us to abandon the bottom-up principle. For example when Swiss firm ID Quantique, one of the world's first quantum companies, was bought up by Korean Telecom. ID Quantique now belongs to a large American start-up. Secure encryption would represent a key strategic technology for Switzerland that should not have been allowed to leave the country. It's not just about applications, though; stronger support is needed for fundamental research nowadays.
What exactly should the Swiss government change?
It should make substantial investments in this field. I know everybody says that about their own field. But Switzerland should take "quantum" more seriously. We have a lot of competition now. Virtually all European countries are pursuing active research policies in this field. Even more so in Asian countries.
And where does the US stand?
That's an entirely different environment. The US is investing enormous amounts in quantum research, with a lot of this coming from industry. The US is probably the only country that is strong in all areas.
Will that continue to hold true, even under Trump's presidency?
Quantum research and development has been treated as a priority by all US presidents to date, including the current administration, and continues to receive enormous amounts of support.
You've been doing research in the field of quantum mechanics for more than 40 years. Apart from the discovery of the first graphene qubits, what would you consider to be the most rewarding insight?
As far as we know, the laws of physics do not impose a fundamental upper limit on how large a quantum system can be. When scaling up qubits, it would be exciting if more new effects appeared that we've never encountered before. That would be fantastic because then we would have found something never described before in quantum mechanics. That would be the most wonderful thing for me. But it's something we haven't managed for a hundred years.
Why would that be the most rewarding experience for you?
Quantum mechanics was discovered because some experimental results were at odds with conventional theories. Discovering that something was fundamentally wrong would be a breakthrough to something new. Then we'd have to find out: What's is the next thing?
Read the first part of the interview with quantum researcher Klaus Ensslin here.
How young quantum researchers at ETH Zurich see the future of quantum technology
