Frank Wilczek, Gerard ’t Hooft, and Duncan Haldane, photographed shortly after the Quantum Connections summer school at Högberga Gård.
As the 2025 Nobel Prize in Physics is awarded this week for advances in quantum mechanics, we look back at insights shared in person by earlier laureates Frank Wilczek, Gerard ’t Hooft, and Duncan Haldane at Nordita’s Quantum Connections summer school. Eager to hear from some of the most influential voices in the field, in a sunlit corner of the Högberga gård summer gardens, we asked them one question:
“What do you think is the most important challenge for the next generation of quantum physicists?”
Frank Wilczek (Nobel Prize in Physics 2004)
Haha — well, I guess the most important challenge is, there are a few, but the most important one might be to have quantum physics finally live up to its potential of putting chemists and materials scientists out of business… by making it possible to do their experiments purely from first principles, through computation. In principle, quantum mechanics contains all of chemistry and most of physics, but in practice we haven’t been able to solve the equations very well. So, with new methods, new computing machines, or some combination of the two, if people can deliver on that, it would change the world in many ways.
Gerard ’t Hooft (Nobel Prize in Physics 1999)
After about 100 years of hefty debates among physicists, it seems as if the special nature of all theoretical descriptions of the properties of systems as small or smaller than molecules, atoms, elementary particles, and the like, is agreed upon: the best theories always tell us that, regardless of how precisely the initial state of such a system is set, the outcome of an experiment turns out to be a probabilistic distribution. As if different “realities” will emerge.
This is alright, as long as one would admit that the exact real state that will emerge could not be calculated. The mixture of realities is then simply a consequence of our lack of knowledge. This was the position Albert Einstein took. I agree with him (although the arguments he used are often challenged).
But our knowledge of the physical world does not have to stay as imperfect as that. The challenge that I see is that we could try to design better models of physical systems such as colliding particles. I want to see models that, in principle, produce a single realistic state if you start with a realistic state at the beginning. This rules out the use of the states that we normally consider, because most of these cannot describe reality (this happens if the set of states you want to use includes superpositions; if states |A⟩ and |B⟩ are assumed to be real then 1/√2 |A+B⟩ cannot be real). People are so used to quantum mechanics that they don’t care about this.
My challenge to quantum physicists is to reformulate quantum rules without admitting superpositions anywhere. I have the quantum harmonic oscillator as an example. There I showed how this works. Why don’t they consider other cases? It’s easy to start working on this problem right away, because no experiment has to be performed. The most important challenge is also the most difficult one: do this for the Standard Model, and/or gravity.
Duncan Haldane (Nobel Prize in Physics 2016)
“What we are trying to do is understand how to verify and control quantum states, both for processing information and for extremely precise measurements. In the past, quantum measurements were often crude—like taking a hammer to a system and analyzing the pieces to see what it was made of. Now, we are exploring entanglement—the quantum relations between parts of a system separated beyond atomic scale.
Nordita used to be more focused on theoretical ‘atomic physics,’ but now it embraces all of physics. Entanglement, which was historically only considered on the atomic scale to understand atoms, is now being explored on much larger scales. The challenge is to preserve quantum states when the components are separated beyond atomic distances, and this is where some of the strangest possibilities arise.
The laws of quantum mechanics haven’t changed since the 1930s, but just knowing the laws doesn’t immediately tell you everything you can do with them—much like Maxwell’s equations in the 19th century only revealed their technological potential over decades. Similarly, entanglement is central to what many call the second quantum revolution. Ideas that Einstein thought were too strange to be real have now been verified experimentally, and we are learning how to exploit them.
A quantum state can store much more information than a classical bit, but these states are extremely fragile. Protecting them and figuring out practical ways to use them is the major challenge for the field. It’s an exciting period because questions that were once purely philosophical are now being realized as experimental and technological possibilities.”
Surrounded by young researchers from around the world at Nordita’s Quantum Connections school, it was striking to hear three very different answers to the question of the future of quantum physics. Who will turn out to be right? Perhaps all of them, in their own way. The 2025 Nobel Prize in Physics aligns well with their intuition that quantum physics should be expanded both experimentally and philosophically so that it becomes closer to us.
The next chapters of quantum physics promise to be fascinating!
