Nobel prize: Physics

Three scientists who were the first to create an exotic, potentially useful state of matter called the Bose-Einstein condensate have won the 2001 Nobel Prize in Physics.

Carl E. Wieman of the University of Colorado in Boulder and Eric A. Cornell of the National Institute of Standards and Technology (NIST), also in Boulder, will share the nearly $1 million prize with Wolfgang Ketterle of the Massachusetts Institute of Technology. The Colorado scientists are members of JILA, a joint institute of NIST and the University of Colorado.

In 1995, Wieman and Cornell together used rubidium-87 atoms to make the world’s first Bose-Einstein condensate (SN: 7/15/95, p. 36). A few months later, Ketterle and his group repeated the feat with sodium atoms (SN: 12/2/95, p. 373).

Depiction of three stages of Bose-Einstein condensation in clouds of rubidium-87atoms. M. Matthews/JILA

A Bose-Einstein condensate is a cloud of gas so extremely cold that its atoms settle into a single, shared quantum state. In effect, the cloud becomes a single superatom. To create such condensates, scientists must prevent the clouds from becoming liquids or solids. Part of the trick is in the choice of atoms and part is in the handling: The condensates form only at temperatures less than a few hundred billionths of a degree above absolute zero.

The first inklings of this novel state of matter surfaced in 1924. That’s when physicists Satyendra Nath Bose and Albert Einstein jointly predicted the extraordinary phenomenon that now bears their names. However, the condensates weren’t created until scientists developed lasers and ways to use them and other instruments to trap and cool atoms (SN: 10/25/97, p. 263).

According to quantum mechanics, atoms behave both as particles and waves, which spread out in space. When the atoms get cold enough, their associated waves coalesce, enabling the formation of a superatom. By making the first Bose-Einstein condensate, Cornell and Wieman set off “a bombshell” in physics, says Theodor W. Hänsch of the Max Planck Institute for Quantum Optics in Garching, Germany. That achievement, along with Ketterle’s parallel work, was “the start of a big wave of excitement,” he adds.

Containing up to a billion atoms, Bose-Einstein condensates have given physicists a new window on the quantum world. The Royal Swedish Academy of Sciences cited Ketterle, in particular, for exploiting the condensates to probe quantum physics and the nature of matter in previously impossible ways. Bose-Einstein condensates may also prove to have practical value. In 1997, Ketterle and his colleagues demonstrated that portions can be extracted intact like drops from a faucet (SN: 2/1/97, p. 71), a step that physicists described as the first atom laser. Since then, researchers have improved upon such lasers so that they can emit atoms in a beam (SN: 5/8/99, p. 296).

Scientists are learning to use atom lasers to improve measurements of gravity, build more precise gyroscopes, and make yet more-accurate atomic clocks. Recently, Hänsch’s team and others have demonstrated that they can condense and then manipulate Bose-Einstein condensates on microchips (SN: 8/4/01, p. 73: Quantum queerness gets quick, compact), a step perhaps toward new compact instruments.

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