American physicist who, with Carl E. Wieman (Wieman, Carl E.) and Wolfgang Ketterle (Ketterle, Wolfgang), won the Nobel Prize for Physics in 2001 for creating a new ultracold state of matter, the so-called Bose-Einstein condensate (BEC).

After studying at Stanford University (B.S., 1985), Cornell earned a Ph.D. from the Massachusetts Institute of Technology in 1990. In 1992 he joined the faculty of the University of Colorado. That year he also became a senior scientist at the National Institute of Standards and Technology.

In the early 1990s Cornell began searching for the Bose-Einstein condensate, which had been predicted some 70 years earlier by Albert Einstein (Einstein, Albert) and the Indian physicist Satyendra Nath Bose (Bose, Satyendra Nath). In this state atoms are so chilled and slow that they, in effect, merge and behave as one single quantum entity that is much larger than any individual atom. In June 1995, working with Wieman, Cornell used a combination of laser and magnetic techniques to slow, trap, and cool about 2,000 rubidium atoms to form a BEC. Cornell's work provided insight into the laws of physics and led to studies on possible practical uses of BECs. He became a member of the National Academy of Scientists in 2000.