At the invitation of the National Time Service Center, Claude Cohen-Tannoudji (C. Cohen - Tannoudji), world-renowned physicist, winner of Nobel Prize in Physics in 1997 and of Quantum Electronics Award by the European Physical Society, professor of the Institut de France and Ecole Normale Superieure, visited the National Time Service Center of Chinese Academy of Sciences in Xi'an as the "Chair Professor of Einstein" from the Chinese Academy of Sciences on March 6, and gave a academic report of "Advances in Ultracold Atomic Gases and Applications", mainlyintroducing the latest progresses and developments of ultracold atomic physics as well as the application of ultracold atomic gases. More than 150 people including scientific & technical personnel of the National Time Service Center, graduate students, and experts from institutes, colleges and universities in Xi'an listened to the report.

Professor Tannoudji has long been engaged in research in the fields of atomic & molecular physics and quantum electrodynamics. Based on their important contributions to the theory and method of laser cooling and trapping of atom, Professor Tannoudji shared the Nobel Prize in Physics with Professor Steven Chu of Stanford University and Professor William D. Phillips of the U.S. National Institute of Standards and Technology in 1997.

The study on laser cooling and trapping of atom is a cutting-edge task in contemporary physics. Control of atoms has been a goal of physicists. Scientists such as Professor Tannoudji took the lead in cooling gases to the range of μK temperature in all manner of ways, revealed the nature of the role of light and atoms, and trapped the cooled-off atoms in different types of "traps". The cooled-off and trapped atoms provided an ideal sample for studying the internal structure of atoms as well as interaction between electromagnetic field and the material, promoted the development of such disciplines as atomic & molecular physics, quantum electrodynamics, etc. Seeing that precision of new atomic clock based on cold atom technology atomic clock improved hundreds times than that of the traditional atomic clock, the precision of measurement of time and frequency, basic physical constants and space navigation and positioning improved greatly. The method of trapping atom through laser cooling led directly to the rapid development of such research areas as Bose- Einstein condensation, matter-wave interference, atomic lasers, etc.

In the activity of "Chair Professor of Einstein from the Chinese Academy of Sciences" this time, Professor Tannoudji will make 4 academic reports respectively in the National Time Service Center, Xi’an, Beijing Graduate School, Institute of Physics of Chinese Academy of Sciences, and Institute of Ray Machine, Shanghai.