Claude Cohen-Tannoudji is a Jewish French physicist and recipient of the 1997 Nobel Prize in Physics.
Cohen-Tannoudji (born April
1, 1933) was born in Constantine, Algeria.
Cohen-Tannoudji moved with his family in 1953 to Paris.
From 1953 to 1957, he attended the Ecole Normale Supérieure.
Following graduation, Cohen-Tannoudji was enlisted in
military service for 28 months because of the Algeria
In 1960, he returned to the Ecole
Normale laboratory to do a Ph.D. under the supervision
of Alfred Kastler and Jean Brossel with a research post
at the CNRS (French National Center for Scientific Research).
He submitted his Ph.D. in December 1962.
After obtaining his doctorate, Cohen-Tannoudji
accepted a professorship at the University of Paris.
In 1973, he was appointed professor at the Collège
He is one of most recognized researchers
in the field of quantum optics, the best-known part
of his work being his part in the development of techniques
to cool and trap atoms with light, for which his was
awarded the 1997 Nobel
Prize in Physics, together with Steven Chu and William
He is also author of a very concise
and hence often used text book, "Quantum Mechanics",
which originated from his teaching experiences at the
University of Paris. This book was written in collaboration
with Franck Laloë and Bernard Diu.
The following press release from the
Royal Swedish Academy of Sciences describes Cohen-Tannoudji's
At room temperature the
atoms and molecules of which the air consists
move in different directions at a speed
of about 4,000 km/hr. It is hard to study
these atoms and molecules because they
disappear all too quickly from the area
being observed. By lowering the temperature
one can reduce the speed, but the problem
is that when gases are cooled down they
normally first condense into liquids and
then freeze into a solid form. In liquids
and solid bodies, study is made more difficult
by the fact that single atoms and molecules
get too close to one another. If, however,
the process takes place in a vacuum the
density can be kept low enough to avoid
condensation and freezing. But even a temperature
as low as -270°C involves speeds of about 400 km/hr.
Only as one approaches absolute zero (-273°C) does
the speed fall greatly. When the temperature is one-millionth
of a degree from this point (termed 1 µK,
microkelvin) free hydrogen atoms, for example,
move at speeds of less than 1 km/hr (=
Steven Chu, Claude Cohen-Tannoudji,
and William D. Phillips have developed
methods of using laser light to cool gases
to the µK temperature
range and keeping the chilled atoms floating or captured
in different kinds of "atom traps".
The laser light functions as a thick liquid,
dubbed optical molasses, in which the atoms
are slowed down. Individual atoms can be
studied there with very great accuracy
and their inner structure can be determined.
As more and more atoms are captured in
the same volume a thin gas forms, and its
properties can be studied in detail. The
new methods of investigation that the Nobel
Laureates have developed have contributed
greatly to increasing our knowledge of
the interplay between radiation and matter.
In particular, they have opened the way
to a deeper understanding of the quantum-physical
behaviour of gases at low temperatures.
The methods may lead to the design of more
precise atomic clocks for use in, e.g.,
space navigation and accurate determination
of position. A start has also been made
on the design of atomic interferometers
with which, e.g., very precise measurements
of gravitational forces can be made, and
atomic lasers, which may be used in the
future to manufacture very small electronic