A trio of scientists won this Tuesday (04/10) the Nobel Prize in Physics: Alain Aspect, French from Paris-Saclay University ; John F. Clauser, an American at Columbia University; and Anton Zeilinger, Austrian at the University of Vienna. The Royal Swedish Academy of Sciences, which presents the award, credited the three laureates with experimentally demonstrating that there is a potential to control subatomic particles that are in a state called “quantum entanglement”.
With roots in the work of Albert Einstein, entanglement is a prediction from quantum mechanics, the area of study of phenomena at the scale of the atom and its components, which leads to the conclusion that if two particles interact in a certain way, but are pulled apart — for example, one in Tokyo and one in Curitiba — if one is measured, the state of the other is instantly changed by the act of measurement. Therefore, the two particles would be “entangled”. Einstein himself called the phenomenon “spooky action at a distance”.
Other physicists who contributed to the area, such as Niels Bohr and Richard Feynman, expressed similar bewilderment to Einstein’s. The area is borderline to human cognitive efforts to understand nature—attracting constant attention from mystics. Still, the math works and so does the application. A large area of research applies quantum mechanics in an attempt to create quantum computers far more powerful than those we have at home and in our pockets, quantum networks and encrypted communication to potentially increase the security of applications such as electronic voting.
For a long time, it was debated why the pair of entangled particles respond together regardless of the distance between them. A breakthrough was made in the years 1960 by John Stewart Bell, who created an equation that predicted that if there are “hidden variables” creating the entanglement, the correlation (a measure of how much two things vary together) between the results of numerous measurements would never exceed a certain value.
The Nobel laureates 2022 worked on Bell’s legacy. John Clauser developed his ideas, leading to a hands-on experiment that ensured that quantum theory cannot be supplanted by another that uses these hidden variables. Alain Aspect redid Clauser’s work, closing gaps left open and making the measurements of the intertwined pair less biased. Finally, Anton Zeilinger carried out a long series of experiments and led a group that demonstrated a phenomenon called “quantum teleportation”, which makes it possible to transmit the state of one particle to another at a distance.
Thanks to the work of the three, “a new kind of quantum technology is emerging,” said Anders Irbäck, head of the Nobel physics committee. Their findings are of great importance, “beyond the fundamental questions regarding the interpretation of quantum mechanics,” he added. The award is an indication that, while debates rage about how to interpret the complicated theory, it is in the applications that experts in the field can converge.