Claude Cohen-Tannoudji, Nobel Physicist, Dies at 93
The French physicist who shared the 1997 Nobel Prize in Physics with Steven Chu and William Phillips died in Paris on October 22, his family says.
French physicist Claude Cohen-Tannoudji, who won the 1997 Nobel Prize in Physics, has died at the age of 93 at his home in Paris. His family told the AFP news agency that he died on Thursday, October 22, 2026, and the Kastler Brossel Laboratory, where he worked, announced his death publicly on Friday, October 23. One French report gives Friday as the day of death, which differs from the family’s account; this article follows the family’s version, and Friday is the day of the announcement.
What did Chu, Phillips and Cohen-Tannoudji develop in the 1980s?
Cohen-Tannoudji shared the 1997 Nobel Prize in Physics with the Americans Steven Chu and William D. Phillips, for methods of cooling and trapping atoms with lasers. Each of the three developed his own methods to that end during the period.
The underlying problem is simple. At room temperature, the atoms and molecules in air move at dizzying speeds, which makes them hard to study and their properties hard to use. To do either, they first have to be cooled, meaning slowed down, and that is exactly what the three physicists achieved with laser beams.
The Kastler Brossel Laboratory is a joint research unit of the Ecole Normale Superieure in Paris, the Sorbonne, the College de France and the French National Centre for Scientific Research (CNRS). In its statement on his death, it said that this research “enabled spectacular progress in the field of cold atoms,” called Cohen-Tannoudji a great figure and paid tribute to his exceptional contributions (quotations are our translation from the French).
The best-known application is the atomic clock. Such clocks are essential for telecommunications and navigation systems and have reached extreme precision, and laser cooling of atoms is the technology behind them.
From Constantine to the College de France
Cohen-Tannoudji was born on April 1, 1933 in Constantine, Algeria. At 20 he came to Paris, to the Ecole Normale Superieure, and he later became a professor at the College de France. He was also a member of the French Academy of Sciences.
In 2013 the American Physical Society awarded him the Andrei Sakharov Prize.
Mentor and textbook author
He supervised the doctoral work of Serge Haroche, who later became a Nobel laureate himself. With Bernard Diu and Franck Laloe he wrote the textbook “Quantum Mechanics.” Nobel laureate Alain Aspect has said that it was this very book that introduced him to physics.
His daughter Joelle Cohen-Tannoudji told AFP, in a statement carried by The Times of Israel, that he loved passing on knowledge:
“He very much loved passing on knowledge, at all levels.”
According to her, he also worked to bring Israeli and Palestinian scientists closer together.
What the sources do not say
The sources available to us do not give a cause of death. They do not mention a funeral either, and the details of his life and awards come from statements by the family and the laboratory as relayed by the media, not from a separate biographical check.
