Nobel prize awarded for quantum entanglement

Business news |
By Nick Flaherty

Researchers from Austria, France and the US have been awarded the 2022 Nobel Prize in Physics for their work on quantum entanglement that is the basis of quantum sensors and quantum computers.

The $1m (SEK10m) prize from the Royal Swedish Academy of Sciences is to Alain Aspect of the Université Paris-Saclay and École Polytechnique in France, Anton Zeilinger of the University of Vienna in Austria and John F. Clauser in California.

Aspect, Clauser and Zeilinger have each conducted groundbreaking experiments using entangled quantum states, where two particles behave like a single unit even when they are separated. The research has cleared the way for new technology based upon quantum information.

There is now a large field of research that includes quantum computers, quantum networks and secure quantum encrypted communication that is being commercialised.

One key factor in this development is how quantum mechanics allows two or more particles to exist in an entangled state. While known in theory, the question was whether the correlation was because the particles in an entangled pair contained hidden variables, instructions that tell them which result they should give in an experiment.

In the 1960s, John Stewart Bell developed the mathematical inequality that is named after him. This states that if there are hidden variables, the correlation between the results of a large number of measurements will never exceed a certain value. However, quantum mechanics predicts that a certain type of experiment will violate Bell’s inequality, thus resulting in a stronger correlation than would otherwise be possible.

While at Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, and the University of California, Berkeley, Clauser developed John Bell’s ideas, leading to a practical experiment. When he took the measurements, they supported quantum mechanics by clearly violating a Bell inequality. This means that quantum mechanics cannot be replaced by a theory that uses hidden variables. He retired in 1996.

Some loopholes remained after John Clauser’s experiment. Aspect developed the setup, using it in a way that closed an important loophole. He was able to switch the measurement settings after an entangled pair had left its source, so the setting that existed when they were emitted could not affect the result.

Using refined tools and long series of experiments, Zeilinger started to use entangled quantum states. Among other things, his research group has demonstrated a phenomenon called quantum teleportation, which makes it possible to move a quantum state from one particle to one at a distance. This has made the University of Austria a powerhouse in quantum technology.

“It has become increasingly clear that a new kind of quantum technology is emerging. We can see that the laureates’ work with entangled states is of great importance, even beyond the fundamental questions about the interpretation of quantum mechanics,” said Anders Irbäck, Chair of the Nobel Committee for Physics.

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