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Nobel laureate 'impressed' by China's atom chips
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Nobel Prize-winning German physicist Wolfgang Ketterle said Tuesday he was "impressed" by Chinese scientists' progress in creating on chips the bizarre state where thousands of atoms lose almost all their energy and behave as one.

A research team from the Chinese Academy of Sciences (CAS) said it had made over 3,000 rubidium atoms condensate on a thumbnail-sized chip for five seconds at a temperature of almost absolute zero (-273.15 degrees Celsius), a state which Albert Einstein was the first to call "condensation" eight decades ago.

Being the second Asian country to achieve this, only beaten by Japan, China is now "rapidly catching up with the frontiers of the field", Ketterle told Xinhua in an email. He shared the 2001 Nobel Prize in Physics with Eric Cornell and Carl Wieman from the University of Colorado for synthesizing the first condensate.

The team at CAS's Shanghai Institute of Optics and Fine Mechanics (SIOM) used lasers this time to cut Z and U-shaped lines 100 microns wide on the gilded surface of a silicon-based chip and generated a magnetic field around the chip by electrifying the lines.

Rubidium atoms were "trapped" in the magnetic field thus generated and, with the help of laser cooling and evaporation, were gradually frozen to a temperature of 0.0000003K (-272.999 degrees Celsius), almost the absolute zero, said SIOM.

The state of condensation for atoms was predicted by Einstein in 1924 based on Indian physicist Satyendra Nath Bose's theories. Since then, the subject of what's called Bose-Einstein Condensate (BEC) has remained hot among the world's brightest physicists.

Ketterle, now a professor at the Massachusetts Institute of Technology, said, "the main impact of atom chips is to miniaturize the experimental setup of BEC."

Traditional research apparatuses for BEC were usually huge, said Wang Yuzhu, a CAS academician who led the research team. "The magnetic field loops alone could take up half the volume of a floor-standing air conditioner, making it very expensive and difficult to do experiments."

Atoms at the BEC state act at the same frequency, like photons in a laser, but stronger, earlier researches in the field showed.

They can be used for the storage and processing of quantum information, and for atomic clocks used in navigation and space flights, Wang said, adding that scientists worldwide are working on the application of this technology.

Ketterle said, he expected Chinese physicists to "make major contributions (to the field of BEC) in the near future."

(Xinhua News Agency December 17, 2008)

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