Facts: Nobel Prize in Physics 2022
Alain Aspect, John Clauser and Anton Zeilinger have each done pioneering experiments with entangled quantum states, where two particles belong together as a unit even when they are separated. With their results, they have paved the way for new technology based on quantum information.
In the 1960s, John Stewart Bell developed the disparity that bears his name. It states that if there are hidden variables, the correlation between the outcomes of a large number of measurements can never exceed a certain value. Quantum mechanics, on the other hand, predicts that a certain type of experiment will violate Bell’s inequality and thus provide a stronger connection than is otherwise possible.
John Clauser further developed John Bell’s ideas into a practical experiment. When he made his measurements, the result supported quantum mechanics, by clearly violating a Bell similarity. This means that quantum mechanics cannot be replaced by a theory with hidden variables.
Some loopholes still remained after John Clauser’s experiments. Alain Aspect developed the experiment and used it to close an important one. He could switch the settings of the measurement after an entwined pair had left their source, lest the arrangement prevailing when they were sent out could affect the outcome.
With refined tools, Anton Zeilinger was able to start using entangled quantum states in a long series of different experiments. For example, his research group demonstrated a phenomenon called quantum teleportation, which makes it possible to move a quantum state from one particle to another far away.
Source: Royal Swedish Academy of Sciences
— In less than 24 hours, I had to learn to set a limit. I have to say no to all the requests that come and have an assistant take care of my calendar, it’s completely new to me.
One of this year’s three Nobel laureates in physics, Frenchman Alain Aspect has had a couple of unusual weeks behind him. Now he’s in Stockholm to receive the prestigious award and he says he doesn’t really know what’s going on – “he’s just following along”.
As a physicist, it is other kinds of boundaries that have been his focus – that between quantum mechanics and classical physics. In the microscopically small world, at the atomic level, different laws apply than in the one we experience.
— Somewhere there is a limit and I would like to find that limit. Then we would get closer to the answer if it is possible to make perfect quantum computers, says Alain Aspect.
Own rules
A common assumption in physics is that two particles can only affect each other if some kind of signal is transmitted between them. Since a signal cannot travel faster than the speed of light in a vacuum, there should be a limit to how fast something in one place can affect something in another place.
But according to the laws of quantum mechanics, it is different. According to it, two particles, such as photons, can be in a so-called entangled state. The entanglement means that what happens in one particle affects the other, even if they are far apart. Furthermore, a measurement of the measurement of the vibrational properties of light, the polarization, of one, immediately affects the other.
It is in this area that he and the two other prize winners, the American John Clauser and the Austrian Anton Zeiliger, have conducted their research.
The Nobel laureates in physics 2022, Alain Aspect, John F. Clauser and Anton Zeilinger during a press conference.
— I am fascinated by the fact that some of these theoretical predictions do not fit our ordinary world, yet we can show that they are correct. It’s so baffling that Einstein didn’t think it was possible, says Alain Aspect.
He says that he has never thought about whether his results will lead to something useful when doing research. He has had questions that he has tried to answer and when he has succeeded he has moved on. That’s why he was stunned the first time a student told him that quantum mechanics could be used to send encrypted information.
— Others are much better at finding applications, that’s not my thing. But it’s incredibly fascinating when it happens, he says.
Impossible to reveal
Put simply, he explains quantum cryptography as having balls with a random series of ones and zeroes distributed between them. Whether it will be a one or a zero is not revealed until we look at the balls.
— If you send a spy there, no one will because there is nothing to spy on. WHETHER it will be a one or a zero, we won’t know until the last moment. It is a completely safe system, says Alain Aspect.
Since he received the news that he is a Nobel laureate, he has not had time to do any research. But, he adds, these days he still mainly lectures. But the curiosity remains, and it shines through during the press conference at the Royal Swedish Academy of Sciences when Alain Aspect, as the only one of nine prize winners on site, happily takes photos of the premises and audience.
He says that he has always experimented with what is available – chalks that are dissolved in vinegar or various tools.
If there is anything that upsets him, it is science skeptics. How anyone can question the UN expert panel’s conclusions that human activity is behind global warming is inconceivable to him
— If you understand how extensive and scrutinized that research is, you cannot object. I usually say that anyone who wants to question should learn science and use it to prove their theories.
He has two pieces of advice for young people who want to pursue science:
— Choose the research that you are attracted to, that attracts you. And read math.