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Nobel laureate Alain Aspect to give May 13 lecture


Nobel laureate Alain Aspect

French physicist Alain Aspect is co-laureate of the 2022 Nobel Prize in physics and a professor at Université Paris-Saclay and École Polytechnique.


Nobel laureate Alain Aspect to give May 13 lecture at Purdue on pioneering efforts in quantum physics and technology


WEST LAFAYETTE, Ind.—Renowned French scientist Alain Aspect, who won the 2022 Nobel Prize for his pathfinding research in quantum physics, will give a lecture on Monday (May 13) at Purdue University on his pioneering work that set in motion a second quantum revolution.

Aspect, a professor of physics at Université Paris-Saclay and École Polytechnique known as the "father of quantum entanglement," shared the Nobel Prize in physics with American physicist John F. Clauser and Austrian physicist Anton Zeilinger for their research using entangled photons to test the quantum foundations of reality.

Their work has advanced a field in quantum physics that famously had been dismissed by Albert Einstein during the 1930s. The result of the trio's Nobel-winning efforts has been a range of new technologies including quantum computing, encryption and more, paving the way for what Aspect today describes as the "second quantum revolution."

His lecture, titled "From Einstein and Bell to Quantum Technologies: Entanglement in Action," is at 2:30 p.m. in the Kurz Atrium in the Neil Armstrong Hall of Engineering. While free and open to the public, please register here. This talk is the last installment of the 2023-24 Purdue Engineering Distinguished Lecture Series, and is co-hosted by the colleges of Engineering and Science.

"French physicist Alain Aspect is among the select group of scientists and researchers today who are behind the current quantum technology revolution," said Arvind Raman, the John A. Edwardson Dean of the College of Engineering. "Through this exciting and informative lecture, the Purdue community will have the opportunity to learn more about Professor Aspect's pioneering, game-changing work in a field that has revolutionized our thinking about quantum physics and technology—and incidentally in the same field that had been famously questioned years ago by Einstein, who called it 'spooky action at a distance.'"


Based on the theory of physics known as quantum entanglement, when a system is split into two, the properties of the two new sub-systems remain connected, as if by an invisible piece of string, regardless of how far apart they are. In 1981, Aspect and his team proved the phenomenon in a laboratory experiment for the first time.

In their groundbreaking experiment, Aspect and collaborators Philippe Grangier, Jean Dalibard and Gérard Roger examined two photons—units of light—with opposite polarizations that were emitted from a heated calcium source. Each photon traveled toward a polarizer 40 feet away. The time for light and any signal to travel between the two polarizers was 40 nanoseconds. Switches would send the photons between the pair of polarizers every 10 nanoseconds.

Essential to their experiment, each polarizer was independent of the other because no signal could travel between the two. The test's success settled a 60-year-old debate between Einstein and Denmark's Niels Bohr, one of the fathers of quantum physics. Bohr believed in the theory of quantum entanglement, but Einstein—whose original research helped predict the phenomenon—famously argued against it.

The results of the study led by Aspect were published in their seminal paper in Physics Review Letters in July 1982.

The independent work by Aspect and his Nobel colleagues Clauser and Zeilinger collectively addressed scientific questions that were investigated during the 1960s. Northern Irish physicist John Stewart Bell had sought to understand what entanglement's "spookiness" implies about the fundamental nature of reality.

At the same time, while scientists today still debate what is fundamentally occurring during the measurement of entangled particles, Aspect's trailblazing experiment demonstrated that it does so within the boundaries of existing quantum theory. That will be the focus of Aspect's talk at Purdue.

"As pointed out by Einstein and confirmed by the violation of Bell's inequalities, entanglement of separated particles is an extraordinary feature of quantum mechanics, suggesting some kind of non-locality. It is now used in quantum technologies," Aspect said in describing the subject of his Purdue lecture. "After recalling what are Bell's inequalities and their experimental tests, I will show how the notion of non-locality provides fruitful intuitions for some quantum communication methods."

Aspect is a member of several academies in France, Austria, the United States, England, Italy and Belgium. In addition to the Nobel Prize in 2022, he has received the CNRS Gold Medal (2005), the Wolf Prize in physics (2010), the Niels Bohr Gold Medal and the Albert Einstein Medal (2012), and Optica's Ives Medal/Quinn Prize of the OSA and the Balzan Prize in quantum information processing and communication (2013).

He received a bachelor's degree from the École Normale Supérieure de Cachan, passing his civil service examination in physics in 1969. Continuing his studies in physics, he attended the Université d'Orsay, receiving a master's degree in 1971 and a PhD in 1983. Aspect performed his national service as a teacher in Cameroon from 1971-74 before starting his PhD and taking a lecturer position at the École Normale Supérieure de Cachan in Paris in 1974.

For his graduate research, Aspect developed experiments to test contemporary thinking about entangled photons. In 1985, he joined Claude Cohen-Tannoudiji’s laboratory at the Collège de France in Paris to work on pioneering experiments on laser cooling of atoms, with Jean Dalibard and Christophe Salomon. He then was appointed a CNRS senior scientist at the Charles Fabry Laboratory at the Institut d’Optique Graduate School on the Université Paris-Saclay campus, serving as a professor and head of the atom optics group, and also as a professor in the École Polytechnique.

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