Frank Verstraete on the Quantum Computing Revolution

My conversation with prize-winning quantum physicist and engineer Frank Verstraete

Since its inception in the early 1990s, quantum computing has evolved into a vibrant field attracting the attention of major tech giants like Google, Amazon, IBM, and Microsoft, as well as big corporates like Wells Fargo, BP, JP Morgan Chase, HSBC and Volkswagen.

I've always been fascinated by this incredibly weird technology, often the subject of a longstanding joke that it’s perpetually "just 10 years away from being fully functional." That’s why – as a fan of his book – I wanted to talk to Frank Verstraete , a Belgian quantum physicist and engineer working at the intersection between quantum information theory and quantum many-body physics: a true pioneer who has won numerous awards, among which the Lieben Prize and the Francqui Prize.

For those of you less familiar with quantum computing, here’s a very short primer: quantum computing is a now 30-year-old field that harnesses the strange laws of quantum mechanics to process information in entirely new ways. Instead of classical bits that are either 1 or 0, quantum computers use quantum bits or qubits that can represent 0 and 1 simultaneously. This enables them to solve certain types of problems much faster than classical computers.

I’m trying not to fall into a rabbit hole, but I also realize that, in order to help you fully appreciate quantum computing, I must also address the eccentricity of quantum mechanics. Quantum mechanics is a physics theory that describes the behavior of matter and energy at the most fundamental (sub)atomic level. And this is where it gets truly fascinating, because (sub)atomic particles exhibit extremely counterintuitive behavior: they can behave both as waves and as particles (a phenomenon called wave-particle duality) and exist in multiple states at once (quantum superposition). Last, but not least, measuring them affects their state (the observer effect).

And it is exactly these “weird” effects that make quantum computing so powerful.

Making a real impact

At the very beginning of his academic career, a professor told Frank that if he wanted to make a real impact, he needed to invest his time in a new field. So he decided to specialize in the - back then - emerging area of quantum computing. The other adjacent reason for his choice was that the field of ?quantum physics contained - and still does - all the big open questions in theoretical physics. “A lot of these open questions are about the quantum many body problem which investigates what happens if you put many particles together”, explained Frank. “What are the mathematics behind that? How can it help us understand high energy physics or superconductivity? These are the types of unanswered questions that interest physicists, who are naturally drawn towards domains that they don’t understand.”

Frank’s multidisciplinary background, which combines physics and engineering, turned out to be very useful in this type of environment. “One the one hand, physicists are a careful breed and on the other, engineers thrive in messiness. They are used to solving problems without really understanding them. The latter mindset is exceedingly valuable when you enter a field of physics where there is still so much to explore and understand.”

A lot of challenges

Frank talks very passionately about his field, but he’s also level-headed, stating that it’s very difficult to predict when the first fully functional quantum computer will be delivered. “Much like nuclear fusion or optical computers, the building of quantum computing hardware turned out to be more complicated than people expected. It’s very hard to isolate a quantum system from its environment. Once that fails, and it is coupled to its environment, information leaks out and the system loses its quantum properties. This results in high error rates and instability in the quantum computations.”

“The engineering problems are humongous”, Frank continued. “On top of that, we’ll need to figure out what types of algorithms we’ll need for this environment. Also, every year new types of quantum architectures surface and we still don’t really know what the winning type will be. There are still many challenges to tackle.”

A new language

On the other hand, developments in quantum computing have also revolutionized the field of quantum physics, introducing a completely new language and approach. When new tools and terminology emerge to address existing challenges, they open a world of possibilities, bringing to light unexplored questions and problems. Even though a commercially viable quantum computer may not be immediately available, the impact of quantum computing on quantum physics has been profound, fundamentally transforming the field through this new perspective.

Although the commercialization of quantum computing may take quite a few years, many companies are already investing in it. Wells Fargo, for instance, which still operates computer systems that are 25 to 30 years old in some cases. Their reasoning is that if quantum computing might become a realistic and usable technology within the next 20 years, they need to start considering it now from an engineering perspective.

Not for personal use

When (or, perhaps, if) quantum computers will be commercialized, we won’t have them in our homes. They aren’t your average run-of-the-mill machines. They won’t help us make better appointments or write articles more efficiently or calculate our taxes. They won’t excel in areas like basic arithmetic, general purpose tasks, data storage, high-precision applications, graphical or small-scale and low-complexity problems. What they are good for, though, is problems that show some type of order and structure but in which you have to explore many, many different parts.

When the whole field of quantum computing started to blossom, many experts first assumed that they would be great at solving a certain type of very complex problems like the Traveling Salesman Problem. The aim there is to find the shortest route between a set of points and locations that must be visited. Today, however, there's a consensus that quantum computers will be completely useless for these kinds of problems because there's not enough structure present in these types of environments.

You need a highly structured yet complex problem like the factoring algorithm, explained Frank, which is crucial for breaking RSA encryption. RSA - named after the surnames of Ron Rivest, Adi Shamir and Leonard Adleman - is one of the oldest widely used systems for secure data transmission, so you can guess what the potential consequences of that could be. This factoring algorithm was discovered by a genius named Peter Shor, an American professor of applied mathematics at MIT. He realized that factoring large numbers is equivalent to finding periods in certain functions. And periodicities and functions are actually related to waves.

A wave-like structure

Imagine that you have a function that repeats itself. Finding the period means determining the interval after which the function repeats. This is a wave-like phenomenon. For a quantum computer to be good at solving a problem, it needs this kind of structure with wave-like features.

Other fields that might benefit from quantum computing with the same characteristics are drug discovery (simulating molecular structures to develop new medicines) and material science (discovering new materials with desirable properties). Some even claim that it might enhance Artificial Intelligence, but according to Frank, it’s not clear yet if that will indeed happen.

Disrupting banks

It’s interesting to note that there are certain industries in which the disruptive potential of quantum computing will be a lot higher than in others. Banks, for instance, if quantum computing will indeed be able to crack the RSA mentioned above. That's why there's a lot of effort these days to come up with cryptography that will guard us against quantum attacks. Because we just don’t know when quantum computers will be fully functional. Could be in 10, 20 or perhaps even 5 years. “An extra challenge is that, once we have a commercial quantum computer, we will also be able to decode all messages that have been sent before the new type of un-crackable cryptography”, added Frank. Which is in itself also very problematic.

I mentioned it earlier, but I loved how critical, yet open-minded Frank is about his own field: “Maybe the endgame of this whole technology will not necessarily be to build a quantum computer. Maybe there will be other kinds of technologies that will come out of this field that are just as interesting. In fact, many people claim that you don't even need a quantum computer for groundbreaking material science or breakthrough research in superconductors.”

“It's important to look at this whole field of quantum computing as the edge, for instance in material science. Because, as we strive to make computing parts - like semiconductors - smaller and faster, we will inevitably encounter quantum effects. But, instead of resisting these effects, we could harness them to achieve remarkable innovations. We could leverage quantum phenomena to create new, commercially viable applications.” And Frank is confident that significant and interesting commercial uses will emerge from this field, even if it’s not quantum computers per sé, in their current form.

Quantum geopolitics

There’s also an interesting geopolitical aspect to quantum computing. That’s not the sole prerogative of the AI and chip industries. Frank explained that a big reason why the US private and public sector are investing so much in the field is because of, quite unsurprisingly perhaps, China’s investments in the matter. Imagine what would happen if China is the first to develop a functioning quantum computer that can break all cryptography. You might imagine that the US would find that problematic, as well as many other countries. In fact, American companies that want to hire a Chinese researcher in the field, need to offer a very good justification, otherwise they won’t get permission.

Yet on the other hand quantum computing is also an incredibly open field, explained Frank. “Nationality, whether Chinese, Russian, or otherwise, is irrelevant as we all collaborate to uncover the fundamental properties of nature. This type of curiosity-driven research is inherently international. In our field, whenever we achieve an exciting result, we write a paper and publish it on arXiv, a website where all papers are accessible long before formal publication and review. This allows everyone to read and build upon the research of others immediately, fostering an extremely open environment.

Of course, this openness might very well be due to the current stage of quantum computing, where significant monetary gains are not yet on the horizon. Once it becomes clear that substantial financial profits can be made, the field may become more guarded and closed, as is for instance the case with the field of AI. But however the field further develops, I’m with Frank in thinking that it will be exciting and will hold great disruptive potential.

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