Claude Cohen-Tannoudji

Claude Cohen-Tannoudji (born 1 April 1933) is a French physicist. He shared the 1997 Nobel Prize in Physics with Steven Chu and William Daniel Phillips for research in methods of laser cooling and trapping atoms. Currently he is still an active researcher, working at the École Normale Supérieure in Paris.[2]

Claude Cohen-Tannoudji
Claude Cohen-Tannoudji
Cohen-Tannoudji in 2007
Born1 April 1933 (age 86)
Alma materEcole Normale Supérieure
University of Paris
Jacqueline Veyrat (m. 1958)
AwardsYoung Medal and Prize (1979)
Lilienfeld Prize (1992)
Matteucci Medal (1994)
Harvey Prize (1996)
Nobel Prize in Physics (1997)
Scientific career
InstitutionsCollege de France
University of Paris
Doctoral advisorAlfred Kastler
Doctoral studentsSerge Haroche
Jean Dalibard

Early life

Cohen-Tannoudji was born in Constantine, French Algeria, to Algerian Jewish parents Abraham Cohen-Tannoudji and Sarah Sebbah.[3][4][5][6] When describing his origins Cohen-Tannoudji said: "My family, originally from Tangier, settled in Tunisia and then in Algeria in the 16th century after having fled Spain during the Inquisition. In fact, our name, Cohen-Tannoudji, means simply the Cohen family from Tangiers. The Algerian Jews obtained the French citizenship in 1870 after Algeria became a French colony in 1830."[7]

After finishing secondary school in Algiers in 1953, Cohen-Tannoudji left for Paris to attend the École Normale Supérieure.[7] His professors included Henri Cartan, Laurent Schwartz, and Alfred Kastler.[7]

In 1958 he married Jacqueline Veyrat, a high school teacher, with whom he has three children. His studies were interrupted when he was conscripted into the army, in which he served for 28 months (longer than usual because of the Algerian War). In 1960 he resumed working toward his doctorate, which he obtained from the École Normale Supérieure under the supervision of Alfred Kastler and Jean Brossel at the end of 1962.[2]


Paris de la Recherche - Claude Cohen-Tannoudji 7
Claude Cohen-Tannoudji in 2010

After his dissertation, he started teaching quantum mechanics at the University of Paris. From 1964-67, he was an associate professor at the university and from 1967-1973 he was a full professor.[2] His lecture notes were the basis of the popular textbook, Mécanique quantique, which he wrote with two of his colleagues. He also continued his research work on atom-photon interactions, and his research team developed the model of the dressed atom.

In 1973, he became a professor at the Collège de France.[2] In the early 1980s, he started to lecture on radiative forces on atoms in laser light fields. He also formed a laboratory there with Alain Aspect, Christophe Salomon, and Jean Dalibard to study laser cooling and trapping. He even took a statistical approach to laser cooling with the use of stable distributions.[8]

His work there eventually led to the Nobel Prize in physics in 1997 "for the development of methods to cool and trap atoms with laser light",[9] shared with Steven Chu and William Daniel Phillips. Cohen-Tannoudji was the first physics Nobel prize winner born in an Arab country.

In 2015, Cohen-Tannoudji signed the Mainau Declaration 2015 on Climate Change on the final day of the 65th Lindau Nobel Laureate Meeting. The declaration was signed by a total of 76 Nobel Laureates and handed to then-President of the French Republic, François Hollande, as part of the successful COP21 climate summit in Paris.[10]


Claude Cohen-Tannoudji, UNESCO, 2011

Selected works

The main works of Cohen-Tannoudji are given in his homepage.[12]

  • Claude Cohen-Tannoudji, Bernard Diu, and Frank Laloë. 1973. Mécanique quantique. 2 vols. Collection Enseignement des Sciences. Paris. ISBN 2-7056-5733-9 (Quantum Mechanics. Vol. I & II, 1991. Wiley, New-York, ISBN 0-471-16433-X & ISBN 0471164356).
  • Claude Cohen-Tannoudji, Gilbert Grynberg and Jacques Dupont-Roc. Introduction à l'électrodynamique quantique. (Photons and Atoms: Introduction to Quantum Electrodynamics. 1997. Wiley. ISBN 0471184330)
  • Claude Cohen-Tannoudji, Gilbert Grynberg and Jacques Dupont-Roc, Processus d'interaction photons-atomes. (Atoms-Photon Interactions : Basic Processes and Applications. 1992. Wiley, New-York. ISBN 0471625566)
  • Claude Cohen-Tannoudji. 2004. Atoms in Electromagnetic fields. 2nd Edition. World Scientific. Collection of his most important papers.

See also


  1. ^ Notable twentieth century scientists: Supplement - Kristine M. Krapp - Google Books. Retrieved 2013-03-09 – via Google Books.
  2. ^ a b c d "Claude Cohen-Tannoudji". Retrieved 2017-12-21.
  3. ^ "Claude Cohen-Tannoudji - French physicist". Retrieved 4 October 2018.
  4. ^ "Archived copy". Archived from the original on 2015-02-13. Retrieved 2015-02-13.CS1 maint: Archived copy as title (link)
  5. ^ Francis Leroy (13 Mar 2003). A Century of Nobel Prize Recipients: Chemistry, Physics, and Medicine. p. 218.
  6. ^ Arun Agarwal (15 Nov 2005). Nobel Prize Winners in Physics. p. 298.
  7. ^ a b c Claude Cohen-Tannoudji. "Claude Cohen-Tannoudji - Autobiographical". Retrieved 13 February 2015.
  8. ^ Bardou, F., Bouchaud, J. P., Aspect, A., & Cohen-Tannoudji, C. (2001). Non-ergodic cooling: subrecoil laser cooling and Lévy statistics.
  9. ^ "The Nobel Prize in Physics 1997". The Nobel Foundation. 1997. Retrieved 14 December 2014.
  10. ^ "Mainau Declaration". Retrieved 2018-01-11.
  11. ^ "Honorary doctorates - Uppsala University, Sweden". Retrieved 4 October 2018.
  12. ^ "Claude Cohen-Tannoudji" (in French). École normale supérieure. Retrieved 14 December 2014.

External links

1933 in France

This article lists notable events, births and deaths from the year 1933 in France. Major occurrences include the founding of Air France via merger, and the Lagny-Pomponne rail accident, which killed 204 people.

1997 in science

The year 1997 in science and technology involved many significant events, listed below.

Ampère Prize

The Prix Ampère de l’Électricité de France is a scientific prize awarded annually by the French Academy of Sciences. Founded in 1974 in honor of André-Marie Ampère to celebrate his 200th birthday in 1975, the award is granted to one or more French scientists for outstanding research work in mathematics or physics. The monetary award is 30,500 euro, funded by Électricité de France.

CNRS Gold medal

The CNRS Gold medal is the highest scientific research award in France. It is presented annually by the French National Centre for Scientific Research (CNRS) and was first awarded in 1954. Moreover, Silver Medals are given to researchers for originality, quality, and importance, while Bronze Medals recognize initial fruitful results.

Charles Hard Townes Award

The Charles Hard Townes Award of The Optical Society is a prize for Quantum Electronics — that is to say, the physics of lasers. Awarded annually since 1981, it is named after the Nobel Prize-winning laser pioneer Charles H. Townes.Former winners include Nobel Prize laureates John L. Hall, Claude Cohen-Tannoudji, Serge Haroche, Arthur Ashkin, and Gérard Mourou.

Cécile DeWitt-Morette

Cécile Andrée Paule DeWitt-Morette (21 December 1922 – 8 May 2017) was a French mathematician and physicist. She founded a summer school at Les Houches in the French Alps. For this and her publications, she was awarded the American Society of the French Legion of Honour 2007 Medal for Distinguished Achievement. Attendees at the summer school included over twenty students who would go on to be Nobel Prize winners, including Pierre-Gilles de Gennes, Georges Charpak, and Claude Cohen-Tannoudji, who identify the school for assisting in their success.

Good quantum number

In quantum mechanics, given a particular Hamiltonian and an operator with corresponding eigenvalues and eigenvectors given by , then the numbers (or the eigenvalues) are said to be "good quantum numbers" if every eigenvector remains an eigenvector of with the same eigenvalue as time evolves.

Hence, if:

then we require

for all eigenvectors in order to call a good quantum number (where s represent the eigenvectors of the Hamiltonian).

In other words, the eigenvalues are good quantum numbers if the corresponding operator is a constant of motion (commutes with the time evolution). Good quantum numbers are often used to label initial and final states in experiments. For example, in particle colliders particles are initially prepared in approximate momentum eigenstates (the particle momentum being a good quantum number for non-interacting particles), then the particles are made collide (particle momentum is not a good quantum number for the interacting particles and thus changes), and after the collision particles are measured in momentum eigenstates (a long time after the collision, particle momentum again is a good quantum number).

Theorem: A necessary and sufficient condition for q (which is an eigenvalue of an operator O) to be good is that commutes with the Hamiltonian .

Proof: Assume .

If is an eigenvector of , then we have (by definition) that , and so :
Kastler-Brossel Laboratory

The Kastler–Brossel Laboratory, located in Paris, France, is a research laboratory specializing in fundamental physics of quantum systems. Founded in 1951 by Alfred Kastler and Jean Brossel, it is a joint research unit operated by the French National Centre for Scientific Research (CNRS), the École normale supérieure, the Pierre-and-Marie-Curie University and the Collège de France.

Lilienfeld Prize

The Julius Edgar Lilienfeld Prize of the American Physical Society, to remember Julius Edgar Lilienfeld, has been awarded annually, since 1989. (It was not awarded in 2002). The purpose of the Prize is to recognize outstanding contributions to physics.

Matteucci Medal

The Matteucci Medal is an Italian award for physicists, named after Carlo Matteucci. It was established to award physicists for their fundamental contributions. Under an Italian Royal Decree dated July 10, 1870, the Italian Society of Sciences was authorized to receive a donation from Carlo Matteucci for the establishment of the Prize.

Matteucci MedalistsSource: Italian Society of Sciences

OSA Fellow

The OSA Fellow is a membership designation of The Optical Society (OSA) that denotes distinguished scientific accomplishment. The bylaws of this society only allow 10% of its membership to be designated as an OSA Fellow. The OSA Fellow requires peer group nomination.

Pierre Aigrain

Pierre Aigrain (28 September 1924 – 30 October 2002) was a French physicist and Secretary of Research in the French Academy of Sciences.The son of an engineer, Pierre Aigrain completed his secondary education in Metz before studying at naval school between 1942 and 1945. In 1945 he became a naval officer at just 21 years old and was sent to study in Norfolk, Virginia, USA. After which he became a Ship-of-the-line Lieutenant in Memphis. In 1946 he was accepted to the Carnegie Institute of Technology in Pittsburgh to study towards a master's degree. He then joined the Department of Electrical Engineering, where Professor F.M. Williams got him a research associate position to prepare a PhD in Electrical Engineering, a certificate he obtained in 1948.In September 1948, Aigrain met Claude Dugas at the Carnegie Institute of Technology who had been sent by Yves Rocard on a CNRS grant (Centre nationale de la researche scientifique / Back translation: National Centre of scientific research) to work with Frederick Seitz (Head of the Physics Department). It was during his studies in Pittsburgh that he met his future wife, Francine Bogard (deceased in 2009), whom he married on February 12, 1947 in New York. Back in France he was assigned to the physics laboratory of the École Normale Supérieure, directed by Yves Rocard, as technical assistant to the Marine Research Center Director (1948–1949). He was working on the physics of germanium transistors.Following this he was an engineer at the Atomic Energy Commission (Commissariat à l'énergie atomique) between the years 1949-1950, then an assistant at the Collège de France (to Jean Laval, Professor of theoretical physics) from 1950 to 1951. Then he went back to engineering at the Atomic Energy Commission from 1951-1952. At the age of 26 in 1950, Aigrain obtained a Ph.D. in Physics from the Faculty of Science at the University of Paris. He created a small research team in the physics laboratory of the École normale supérieure with Claude Dugas to conduct research on semiconductors which went on to become the school's laboratory for solid-state physics, he would go on to lead this team until 1965. It is here where Pierre-Gilles de Gennes studied for his graduate degree.

In 1952, aged 28, he resigned from the French Navy and became a temporary lecturer in theoretical physics at the Science Faculty of the University of Lille, all while remaining attached to the Physics Department at the École normale supérieure where he was also lecturing between 1952-1953. On 1 October 1954, he became a permanent lecturer at the University of Paris's Science Faculties for the teaching of the PCB certificate (Certificat d'études physiques, chimiques et biologiques / Back translation: Certificate of physical, chemical and biological sciences) alongside Maurice Curie, Jean-Paul Mathieu and André Guinier, then Paul Soleillet and Jean Brossel. He obtained a senior lecturing role on 1 January 1957 and was then appointed full Professor of Electrical Engineering by 1 October 1958 after the retirement of Marcel Pauthenier. By 1 October 1963, Aigrain was transferred to the Atomic Energy Department. Furthermore, in 1955 he participated in the establishment of the third cycle of solid-state physics with Jacques Friedel and André Guinier,

and in atomic and statistical physics with Jean Brossel, Alfred Kastler, Jacques Yvon, Pierre-Gilles de Gennes and Claude Cohen- Tannoudji.

Serge Haroche

Serge Haroche (born 11 September 1944) is a French physicist who was awarded the 2012 Nobel Prize for Physics jointly with David J. Wineland for "ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems", a study of the particle of light, the photon. This and his other works developed laser spectroscopy. Since 2001, Haroche is a Professor at the Collège de France and holds the Chair of Quantum Physics. In 1971 he defended his doctoral thesis in physics at the University of Paris VI, his research has been conducted under the direction of Claude Cohen-Tannoudji.

Sisyphus cooling

Sisyphus cooling (sometimes called polarization gradient cooling) is a type of laser cooling of atoms used to reach temperatures below the Doppler cooling limit. This cooling method was first proposed by Claude Cohen-Tannoudji in 1989, for which he received part of the Nobel Prize in Physics in 1997.

Sisyphus cooling can be achieved by shining two counter-propagating laser beams with orthogonal polarization onto an atom sample. The two interfering beams create a standing wave with a polarization gradient that alternates between σ+, π and σ− polarisation. Atoms moving through the potential landscape along the direction of the standing wave lose kinetic energy as they move to a potential maximum, at which point optical pumping moves them to a lower-energy state, thus ridding them of the potential energy they carried.

Repeated cycles of converting kinetic energy to potential energy, and subsequent loss of this potential energy via optical pumping, allow the atoms to reach temperatures orders of magnitude below those available through simple Doppler cooling.

The technique is named after Sisyphus, a figure in the Greek mythology, who was doomed, for all eternity, to roll a stone up a mountain only to have it roll down again whenever he got near the summit.

State space (physics)

In physics, a state space is an abstract space in which different "positions" represent, not literal locations, but rather states of some physical system. This makes it a type of phase space.

Specifically, in quantum mechanics a state space is a complex Hilbert space in which the possible instantaneous states of the system may be described by unit vectors. These state vectors, using Dirac's bra–ket notation, can often be treated like coordinate vectors and operated on using the rules of linear algebra. This Dirac formalism of quantum mechanics can replace calculation of complicated integrals with simpler vector operations.

Steven Chu

Steven Chu (Chinese: 朱棣文; pinyin: Zhū Dìwén, born February 28, 1948) is an American physicist and a former government official. He is known for his research at Bell Labs and Stanford University regarding the cooling and trapping of atoms with laser light, for which he won the Nobel Prize in Physics in 1997, along with his scientific colleagues Claude Cohen-Tannoudji and William Daniel Phillips.Chu served as the 12th United States Secretary of Energy from 2009 to 2013. At the time of his appointment as Energy Secretary, Chu was a professor of physics and molecular and cellular biology at the University of California, Berkeley, and the director of the Lawrence Berkeley National Laboratory, where his research was concerned primarily with the study of biological systems at the single molecule level.Chu resigned as energy secretary on April 22, 2013. He returned to Stanford as Professor of Physics and Professor of Molecular & Cellular Physiology.

Chu is a vocal advocate for more research into renewable energy and nuclear power, arguing that a shift away from fossil fuels is essential to combating climate change. He has conceived of a global "glucose economy", a form of a low-carbon economy, in which glucose from tropical plants is shipped around like oil is today.On February 22, 2019, Chu began a one-year term as president of the American Association for the Advancement of Science.

William Daniel Phillips

William Daniel Phillips (born November 5, 1948) is an American physicist. He shared the Nobel Prize in Physics, in 1997, with Steven Chu and Claude Cohen-Tannoudji.

École de physique des Houches

L’École de Physique des Houches (the Physics School of Les Houches) was founded in 1951 by a young French scientist, Cécile DeWitt-Morette.

Historically the first lessons were given in 1951 by Léon van Hove on quantum mechanics. The conditions were very spartan with the lessons lasting eight weeks in alpine chalets devoid of all comforts, a few kilometers from the village of Les Houches.

Soon, the school rapidly attracted the greatest names of modern physics, such as Enrico Fermi, Wolfgang Pauli, Murray Gell-Mann and John Bardeen amongst others. The young students, then unknown, included such future scientists as Pierre-Gilles de Gennes, Georges Charpak, and Claude Cohen-Tannoudji, all future winners of the Nobel prize for Physics, as well as mathematician Alain Connes, future winner of the Fields medal.

1997 Nobel Prize laureates
Physiology or Medicine
Economic Sciences

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