Breaking Down the Quantum Research That Earned Three Physicists the Nobel Prize

On Tuesday, the Royal Swedish Academy of Sciences awarded the 2022 Nobel Prize in Physics to Alain Aspect, John Clauser and Anton Zeilinger for experiments in quantum science. Each will receive a third of the 10 million Swedish kronor (roughly $900,000) prize that accompanies the honor.

Their research laid the groundwork for ultra-secure communications and complex computing, and it demonstrated that quantum mechanics—the field that deals with the motion and interaction of the smallest particles—is fundamentally weird.

The three researchers conducted experiments that showed a special state called “entanglement,” when multiple tiny particles are linked, in a sense, so that what happens to one determines what happens to the others, even when they are separated by large distances, the Nobel committee wrote in a press release. When a scientist determines the state of a particle, all the others that are “entangled” with it will immediately take on the same state, regardless of where they are, even if they’re in a distant galaxy, writes Lee Billings for Scientific American.

Working independently, Clauser and Aspect proved this phenomenon can’t be explained by the typical laws of physics, and Zeilinger demonstrated that entanglement can “teleport” information between linked particles, Science’s Adrian Cho reports.

The laureates’ work “has basically opened up this whole field of quantum information science and technologies,” Ronald Hanson, a quantum physicist at the Delft University of Technology in the Netherlands tells Science.

The experiments carried out by the Nobel prize winners were related to a debate between scientists in the 1930s over the nature of reality, writes Charlie Wood for Quanta. Albert Einstein believed that all objects have precisely defined properties, but the physicists Niels Bohr and Erwin Schrödinger argued a fundamental idea of quantum theory: that objects’ properties exist in a state of uncertainty until they are measured. (Think: Schrödinger’s cat is both alive and dead until you open the box.)

Einstein thought there was no state of uncertainty—even if a particle’s properties, such as an electron’s position, appeared to be uncertain, he argued that “hidden variables” unseen to scientists must define them. Otherwise, whatever influenced these particles would have to move faster than the speed of light to make an instantaneous change in their far-off entangled companions, and nothing can travel faster than light-speed, Einstein argued.

In the 1960s, physicist John Stewart Bell devised a thought experiment that relied on pairs of entangled particles to theoretically test Einstein’s idea, according to Science. Essentially, he imagined that two people simultaneously observed different particles that were entangled together. If hidden variables truly existed, the properties of entangled pairs would be correlated, but only up to a certain degree, writes Science.

In 1972, Clauser and colleagues carried out the first successful real-world version of Bell’s thought experiment. Because they measured super-strong correlations, their experiment suggested that quantum mechanics was right. This surprised Clauser, who had expected the results to support Einstein’s ideas, per Quanta.

A decade later, Aspect and colleagues conducted a more refined experiment that ruled out another potential explanation for entanglement, further supporting quantum theory. The last major loophole from Bell’s experiment was closed in 2015, according to Scientific American.

If the idea of entanglement still sounds confusing—it is. Not even the laureates themselves know why it happens, report Seth Borenstein, Maddie Burakoff and Frank Jordans of the Associated Press (AP). Yet each of them, in their respective research, has proved that it exists.

“I have no understanding of how it works, but entanglement appears to be very real,” Clauser says to the AP.

Zeilinger and colleagues focused on studying the use of entangled particles, per Scientific American. In 1998, for example, his team entangled a photon from one entangled pair with a photon from a different entangled pair.

This finding has implications for transmitting information over long distances in a quantum internet, which could enable ultra-secure, encrypted communications, according to Science. These innovations might also lead to new sensors and telescopes, writes Nature News’ Davide Castelvecchi and Elizabeth Gibney.

Entanglement has also aided preliminary work related to quantum computers, which carry out calculations too complex for conventional computers, per Nature News.

“The burgeoning investments in quantum technologies now occurring all over the world are building on scientific foundations, which flow from the pioneering work of Bell, Clauser, Aspect and Zeilinger,” John Preskill, a quantum information scientist at the California Institute of Technology, tells Scientific American.

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.