Claude Cohen-Tannoudji

Nobel Prize in Physics


Studying atoms and molecules is tricky to say the least. They’re invisible to the naked eye, and whizz around at breakneck speeds when at room temperature. For scientists to observe these particles in sufficient detail, they had to first find a way of slowing them down.

The solution came in the 1980s, when three scientists developed the techniques of laser cooling. Working on helium atoms, they discovered that shining a laser beam from different directions cooled the atoms to extremely low temperatures. The light “bumped” into the atoms, causing them to lose energy and decelerate to roughly two centimetres per second. At these super chilled temperatures — close to absolute zero, the point at which all movement theoretically stops — atoms could be “trapped” and studied in detail.

Physicist Claude Cohen-Tannoudji is one of the three scientists who conducted pioneering work on laser cooling. Together with Steven Chu and William Phillips, Professor Cohen-Tannoudji was awarded the Nobel Prize in Physics in 1997. Their work furthered the understanding of how light and matter interact. It also paved the way for ever-smaller electronic parts and extremely precise instruments, such as atomic clocks, to be made.

Professor Cohen-Tannoudji was born in Constantine, French Algeria. He attributes his passion for learning, debate and discussion, and sharing knowledge with others to his father, who he describes as a self-taught man with “great intellectual curiosity.” 

After completing his secondary education in Algiers, Professor Cohen-Tannoudji moved to Paris to attend the elite Ecole Normale Supérieure. Initially intending to major in mathematics, he switched to physics after attending a series of lectures by Alfred Kastler, who would later receive the 1966 Nobel Prize in Physics. “Kastler’s lectures were so stimulating, and his personality was so attractive, that I ended up changing to physics,” recalled Professor Cohen-Tannoudji. He joined Professor Kastler’s lab to do his PhD, after spending 28 months in mandatory military service.

In addition to the Nobel Prize, Professor Cohen-Tannoudji has received numerous awards, including the Thomas Young Medal, Prize of the Institute of Physics, the Lilienfeld Prize of the American Physical Society, the Charles Townes Award of the Optical Society of America, and the Gold Medal of the Centre National de la Recherche Scientifique. He was appointed Professor at the Collège de France in 1973. A member of the French Academy of Sciences, Professor Cohen-Tannoudji has authored over 200 publications in the fields of quantum mechanics, quantum optics, and laser cooling. He is a co-author of the two-volume textbook Quantum Mechanics, which is considered essential reading by physics undergraduate students worldwide.