Cornell was born in Palo Alto, California, where his parents were completing graduate degrees at nearby Stanford University.

Here he grew up with his younger brother and sister, with year-long stints in Berkeley, California, and Lisbon, Portugal, accompanying his father whilst on sabbatical.

Halfway through his undergraduate years he went to China and Taiwan for nine months to volunteer teaching conversational English and to study Chinese.

There he joined David Pritchard's group, which had a running experiment that tried to measure the mass of the electron neutrino from the beta decay of tritium.

[1] After obtaining his doctorate he joined Carl Wieman at the University of Colorado Boulder as a postdoctoral researcher on a small laser cooling experiment.

[2] He is currently a professor at the University of Colorado Boulder and a physicist (NIST fellow) at the United States Department of Commerce National Institute of Standards and Technology.