AFP

Physicists Alain Aspect, John Clauser and Anton Zeilinger developed experimental tools that helped prove quantum entanglement — a phenomenon Albert Einstein famously dismissed as “spooky action at a distance” — is real, paving the way for its use in powerful computers.

Here are mini biographies of the three scientists. 

– John Clauser –

Born in 1942, John Francis Clauser’s earliest memories were of gaping in wonder at the equipment in the lab of his father, who created the aeronautics department for Johns Hopkins, he told the American Institute of Physics in a 2002 oral history. 

An electronics buff who built some of the first computer-driven video games at high school, Clauser opted for physics at college.

In the mid-1960s, he grew interested in the ideas of quantum mechanics pioneer John Bell, who strove to better understand entanglement — when two particles behave as one and can affect each other, even at vast distances.

“I thought this is one of the most amazing papers I’ve ever read in my own life, and I kept wondering, gee, where’s the experimental evidence?”  Clauser told PBS in 2018.

Clauser believed he could test Bell’s ideas in a laboratory, but was met with widespread scorn by leading physicists of the time.

He proposed the test independently of his thesis work on radio astronomy, and carried it out with collaborators in 1972 while at UC Berkeley. 

By shining lasers at calcium atoms to emit entangled photons and measuring their properties, he was able to prove with hard data that what had defied the imagination even of the great Einstein — was true.

– Alain Aspect –

Like Clauser, Frenchman Alain Aspect was seduced by the “limpid clarity” of Bell’s theorem.

“Quantum strangeness has dominated my whole life as a physicist,” he told AFP in a 2010 interview.

As a doctoral student, Aspect built on the work of Clauser, refining the experiment to eliminate possible loopholes in its design — publishing his work in 1982.

The son of a teacher, Aspect was born in 1947 in a village in Gascony, and is currently a professor at Institut d’Optique Graduate School (Augustin Fresnel chair), in University Paris-Saclay, and at Ecole Polytechnique.

But his interest in the quantum realm stemmed from a period in his life spent away from academia — he had gone to Cameroon to complete three years of voluntary service as a teacher.

During his free time, he came across a book written by Claude Cohen-Tannoudji on the subject (Cohen-Tannoudji won the Nobel in 1997), which in turn led him to Bell.

In a phone interview with the Nobel Foundation on Tuesday, Aspect emphasized the international makeup of his co-winners — an American and an Austrian — was an important signal in the face of rising nationalism around the world.

“It’s important that scientists keep their international community at a time when… nationalism is taking over in many countries,” he said.

– Anton Zeilinger – 

Nicknamed the “quantum pope”, the physicist Anton Zeilinger, born in 1945 in Ried im Innkreis in Austria, became one of the most famous scientists in his country by succeeding for the first time in 1997 in quantum teleportation of light particles.

A success quickly compared to the “teleportation” of the television series “Star Trek.”

Using the properties of quantum entanglement for cryptography, Professor Zeilinger encrypted the first banking transaction by this means in Vienna in 2004.

In 2007, his team created entangled pairs of photons and fired one of each pair over 144 kilometers (89 miles) between the Canary Islands La Palma and Tenerife, to generate a quantum cryptographic key.

His fame comes in part from his tireless didactic talents: always keen to popularize his knowledge to the general public, he even initiated the Dalai Lama in 2012 with infectious enthusiasm.

Attached to the University of Vienna, Zeilinger corresponds in all respects to the image of the scientist: gray hair, a full beard, and small round glasses.

He had already received countless awards and did not really believe that he would one day win the Nobel. “There are so many other candidates,” he said a few years ago to the Austria Press Agency

This year’s physics Nobel prize was awarded Tuesday to three men for their work on a phenomenon called quantum entanglement, which is so bizarre and unlikely that Albert Einstein was sceptical, famously calling it “spooky”.

So how exactly does it work?

Even people with degrees in physics struggle to understand it — and some who do still find parts “hard to swallow,” said Chris Phillips, a physicist at Imperial College London.

To explain the phenomenon he used the example of a photon — “a single unit of light” — though the theory is believed to hold true for other particles.

If a photon is put through a “special crystal”, it can be split into separate photons, he told AFP.

“They’re different colours from the one you started with,” Phillips said, “but because they started from one photon, they are entangled”.

This is where it gets weird. If you measure one photon it instantly affects the other — no matter how far you separate them.

This is not supposed to happen. Einstein’s theory of relativity says nothing can travel faster than the speed of light.

And they are inextricably bound together. When you observe the first photon, there are even odds that it will show itself as “either up or down”, Phillips said. But if it is up, then its twin is instantly forced down, or vice versa. 

– New way to kill Schroedinger’s cat –

He extended the famous quantum thought experiment of Schroedinger’s cat, in which a hypothetical animal locked inside a box with a flask of poison remains simultaneously alive and dead — until the moment the box is opened.

For quantum entanglement, if you have two cats in two boxes, by opening one you would “kill that cat and instantaneously — on the other side of the universe — the other cat has been killed,” Phillips said.

Phillips has seen this “extremely strange thing” first hand in his laboratory, where he has two beams of photons set up.

“I can put my hand in one beam and something happens to the other beam on the other side of the room instantaneously — I see a needle flick,” he said.

“That would still be true if my laboratory was millions of miles across.”

It was the fact that this occurs instantly that bothered Einstein, who dismissed this element of quantum entanglement — called non-locality — as “spooky action at a distance” in 1935.

He instead believed that “hidden variables” must somehow be behind what was happening.

In 1964, influential physicist John Stewart Bell found a way to measure whether there were in fact hidden variables inside quantum particles.

Two decades later, French physicist Alain Aspect, who won the Nobel on Tuesday, and his team were among the first able to test Bell’s theory in a laboratory.

By testing its limits, they found that “quantum mechanics resists all possible attacks,” Aspect said in an interview published by the Nobel Foundation after his win on Tuesday.

– ‘Totally crazy’ –

In doing so, Aspect proved Einstein wrong. But he was magnanimous to history’s greatest physicist.

“I like to say that Einstein’s owes a great, great merit in raising the question,” Aspect said, adding that “non-locality does not allow you to send a useful message faster than light”.

Even Aspect finds it weird to have accepted the idea of something “totally crazy” like non-locality into “my mental images,” he said.

The other physics Nobel winners, Austria’s Anton Zeilinger and John Clauser of the US, also tested Bell’s theory, ruling out loopholes and helping pave the way for what has been called the “second quantum revolution”.

Discoveries by Zeilinger, dubbed the “quantum pope”, have shown the potential for quantum entanglement to be used in encryption, quantum teleportation and more. 

Phillips from Imperial College London has developed a prototype the size of a hi-fi sound system that uses quantum entanglement to diagnose breast cancer.

But perhaps the greatest mystery about quantum entanglement remains one that puzzled Einstein nearly a century ago: why does it occur?

“We have to be humble in the face of physics,” Phillips said, adding that it was the same as any another aspect of nature.

“It just is.”

A trio of physicists on Tuesday won the Nobel Prize for discoveries in the field of quantum mechanics that have paved the way for quantum computers, networks and secure encrypted communication.

Alain Aspect of France, John Clauser of the United States and Austria’s Anton Zeilinger were honoured for “groundbreaking experiments using entangled quantum states, where two particles behave like a single unit even when they are separated”, the committee said.

“It has become increasingly clear that a new kind of quantum technology is emerging,” said Anders Irback, chair of the Nobel Committee for Physics.

Albert Einstein and two other physicists first brought up the idea of quantum entanglement in 1935, in a thought experiment that became known as the EPR paradox. 

– ‘Spooky action’ –

It involved two or more particles that existed in an “entangled” state, which means that what happens to one determines what happens to the other. 

This occurs even if they are far apart, something Einstein dismissed as “spooky action at a distance”.

While quantum mechanics have proved the iconic physicist wrong, Aspect said Einstein still played an important role in identifying the issue.

“We must give the credit to Einstein to have raised the equation,” Aspect said in his Nobel Foundation interview.

Aspect, a professor at the Paris-Saclay University, also noted the international makeup of the group as an important signal in the face of rising nationalism around the world, which he urged the scientific community to stand against.

“It’s important that scientists keep their international community at a time when… nationalism is taking over in many countries,” he said in a phone interview with the Nobel Foundation published on YouTube.

Aspect and Clauser, a research physicist based in California, were singled out for their developments on the work of John Stewart Bell, who in the 1960s “developed the mathematical inequality that is named after him”.

First, Clauser “built an apparatus that emitted two entangled photons at a time”, through a filter to test their polarisation. 

“The result was a clear violation of a Bell inequality and agreed with the predictions of quantum mechanics,” the jury said.

Aspect then closed one loophole that meant the measurement setting did not affect the results after the entangled pair had left its source.

– ‘Second revolution’ –

Zeilinger, a professor of physics at the University of Vienna, was highlighted for his work on “quantum teleportation, which makes it possible to move a quantum state from one particle to one at a distance”, the jury said.

“It is not like in the ‘Star Trek’ films or whatever, transporting something — certainly not the person — over some distance,” Zeilinger said.

“But the point is, using entanglement you can transfer all the information which is carried by an object over to some other place where the object is reconstituted.”

The physicists have been credited with paving the way towards what has been called the “second quantum revolution”.

“The first quantum revolution allowed us to have transistors, semi contactors, computers and lasers,” Mohamed Bourennane, a professor in quantum information at Stockholm University, told AFP.

“But the second revolution, which is based on superposition and entanglement, will allow us in the future to have new devices like quantum computers,” he added.

Clauser, Aspect and Zeilinger were also honoured together when they received the prestigious Wolf Prize in 2010.

The three, who will share the Nobel award sum of 10 million Swedish kronor ($901,500), will receive the prize from King Carl XVI Gustaf at a formal ceremony in Stockholm on December 10, the anniversary of the death in 1896 of scientist Alfred Nobel, who created the prizes in his last will and testament.

The scientists were congratulated by French president Emmanuel Macron, who noted Einstein’s scepticism.

“Einstein himself did not believe in quantum entanglement! Today, the promises of quantum computing are based on this phenomenon,” Macron tweeted

Last year, the academy honoured Syukuro Manabe, of Japan and the United States, and Klaus Hasselmann of Germany for their research on climate models. 

Italian Giorgio Parisi also won for his work on the interplay of disorder and fluctuations in physical systems.

The physics prize will be followed by the Nobels for chemistry on Wednesday, the highly watched literature and peace prizes on Thursday and Friday respectively, and the economics prize on Monday.

A trio of physicists on Tuesday won the Nobel Prize for discoveries in the field of quantum mechanics that have paved the way for quantum computers, networks and secure encrypted communication.

Alain Aspect of France, John Clauser of the United States and Austria’s Anton Zeilinger were honoured for “groundbreaking experiments using entangled quantum states, where two particles behave like a single unit even when they are separated”, the committee said.

Their results “have cleared the way for new technology based upon quantum information”.

“It has become increasingly clear that a new kind of quantum technology is emerging,” Anders Irback, chair of the Nobel Committee for Physics, said in a statement.

Aspect, a professor at the Paris-Saclay University, said the international makeup of the group was an important signal in the face of rising nationalism around the world, which he urged the scientific community to stand against.

“It’s important that scientists keep their international community at a time when … nationalism is taking over in many countries,” Aspect said in a phone interview with the Nobel Foundation published on YouTube.

– ‘Spooky action’ –

Albert Einstein and two other physicists first brought up the idea of quantum entanglement in 1935, in a thought experiment that became known as the EPR paradox. 

It involved two or more particles that existed in an “entangled” state, which means that what happens to one determines what happens to the other. This occurs even if they are far apart, something Einstein dismissed as “spooky action at a distance”.

While quantum mechanics have proved the iconic physicist wrong, Aspect said Einstein still played an important role in identifying the issue.

“We must give the credit to Einstein to have raised the equation,” Aspect said in his Nobel Foundation interview.

Aspect and Clauser, a research physicist based in California, were singled out for their developments on the work of John Stewart Bell, who in the 1960s “developed the mathematical inequality that is named after him”.

First, Clauser “built an apparatus that emitted two entangled photons at a time”, through a filter to test their polarisation. 

“The result was a clear violation of a Bell inequality and agreed with the predictions of quantum mechanics,” the jury said.

Aspect then closed one loophole that meant the measurement setting did not affect the results after the entangled pair had left its source.

– ‘Second revolution’ –

Zeilinger, a professor of physics at the University of Vienna, was highlighted for his work on “quantum teleportation, which makes it possible to move a quantum state from one particle to one at a distance”, the jury said.

“It is not like in the ‘Star Trek’ films or whatever, transporting something — certainly not the person — over some distance,” Zeilinger said.

“But the point is, using entanglement you can transfer all the information which is carried by an object over to some other place where the object is reconstituted.”

The physicists have been credited with paving the way towards what has been called the “second quantum revolution”.

“The first quantum revolution allowed us to have transistors, semi contactors, computers and lasers,” Mohamed Bourennane, a professor in quantum information at Stockholm University, told AFP.

“But the second revolution, which is based on superposition and entanglement, will allow us in the future to have new devices like quantum computers,” he added.

Clauser, Aspect and Zeilinger were also honoured together when they received the prestigious Wolf Prize in 2010.

The three, who will share the Nobel award sum of 10 million Swedish kronor ($901,500), will receive the prize from King Carl XVI Gustaf at a formal ceremony in Stockholm on December 10, the anniversary of the death in 1896 of scientist Alfred Nobel, who created the prizes in his last will and testament.

Last year, the academy honoured Syukuro Manabe, of Japan and the United States, and Klaus Hasselmann of Germany for their research on climate models. Italian Giorgio Parisi also won for his work on the interplay of disorder and fluctuations in physical systems.

The physics prize will be followed by the Nobels for chemistry on Wednesday, the highly watched literature and peace prizes on Thursday and Friday respectively, and the economics prize on Monday.