Seeing the world the quantum way

"Thanks to our existing physical theories, we know how to describe physics from the perspective of the platform and the one of the moving train," says Anne-Catherine de la Hamette, who recently completed her PhD at the Vienna Doctoral School in Physics. "But what if the train were in a quantum superposition of different speeds? What would the laws of physics look like then ‒ and what would the world look like from the perspective of the train?"

Physics in quantum reference frames

"Symmetries play a foundational role in physics and give rise to the conservation laws that govern our universe," continues the physicist. "Whether I perform an experiment today or tomorrow, here or in the room next door, the outcome depends only on the conditions of the experiment, not on when or where it is performed."

In a world governed by symmetries, many physical quantities only make sense when defined relative to something else. "That is why we always rely on reference systems ‒ like clocks or rulers ‒ to describe motion, time, or position. My research investigates what happens when these reference systems themselves are quantum systems."

Challenging the concept of reality

Anne-Catherine de la Hamette specialises in the conceptual foundations of quantum physics. It is a field that challenges our classical viewpoints about reality. "Our research does not just add new layers to existing theories ‒ it forces us to rethink what we mean by reality itself," says de la Hamette.

Her daily work requires precision, creativity and teamwork. "We often meet at the blackboard to exchange ideas, come up with thought experiments, and figure out how to ask the right questions. I spend a lot of time thinking, doing calculations, reading papers, and working out clear logical arguments."

Understanding today's key technologies

Apart from reshaping our understanding of the world we live in, foundational quantum research has led to technologies that transformed society or might do so in the future – from lasers and semiconductors to quantum computing and quantum encryption.

"As these technologies become more integrated into everyday life, understanding their conceptual foundations becomes increasingly relevant for society", states de la Hamette and lauds the stimulating research environment at the University of Vienna: "It is a great place to explore some of the most fundamental questions in physics. Here in Vienna, where quantum research has a long and rich tradition, the field is not a niche but a central part of the research landscape."