Three Scientists Share Physics Nobel Prize for Quantum Mechanics Work

The 2022 Nobel prize in physics has been won by three researchers for their work on quantum mechanics.

Alain Aspect, John F Clauser and Anton Zeilinger have won the 10m Swedish kronor (£802,000) prize announced on Tuesday by the Royal Swedish Academy of Sciences in Stockholm. All three will receive an equal share of the prize.

According to the official citation for the award, the prize was given “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science”.

The three physicists’ work has focused on exploring how two particles interact, behaving like a single unit, even when they are far apart. The phenomenon, known as quantum entanglement, was dubbed “spooky action at a distance” by Albert Einstein, and is expected to play an important role in quantum computing.

Quantum entanglement, in a nutshell, means that the properties of one particle can be deduced by examining the properties of a second particle – even if they are separated by a distance. An easy way to imagine this is to think about being given one of two balls – one of which is white and the other is black. If you receive a white ball, you know the ball that remains is black.

Importantly, however, the properties of each particle are not fixed until they are examined – in the ball scenario this would mean that both balls are grey until looked at, where upon one turns white and the other black.

This lies at the heart of the “spookiness” – the two particles, or balls, appear to be connected, without the need for any signal to be sent between them.

One possibility mooted by physicists was that the particles, or balls in the case above, might contain some secret information or “hidden variables”, that determine their properties and, in the early 1960s, the Northern Irish physicist John Stewart Bell proposed that it would be possible to test this by carrying out multiple runs of a particular type of experiment and looking at the way the results are correlated, a theory that gave rise to what is known as Bell’s inequality.

Inspired by Bell’s work, American physicist John Clauser and his colleagues conducted elegant experiments involving polarised light to show that particles do not contain secret information. In other words, the balls in the scenario above do not contain hidden instructions about which colour to turn. Instead, as predicted by quantum mechanics, which one turns black is down to chance.

Alain Aspect developed this work, refining the experiments to close loopholes that might still have allowed the hidden variables theory to hold, while Anton Zeilinger and his colleagues built on the principles to explore entangled systems involving more than two particles.

Prof Jeff Forshaw, a particle physicist at the University of Manchester, said the award of the prize was terrific news.

“This is richly deserved because these are the pioneers of modern quantum physics,” he told the Guardian. “Their experiments confirmed the most bizarre and possibly most important aspect of quantum theory – entanglement.”

by Nicola Davis, The Guardian |  Read more:

Image: Tt News Agency/Reuters
[ed. See also: The big idea: why relationships are the key to existence (Guardian).]