Steven Chu

Steven Chu was born in St. Louis, Missouri, on 28 February 1948, to Chinese immigrant parents in a family of formidable academic achievement — he has described himself as the family's academic underachiever for taking only a Berkeley doctorate. He studied at Rochester and took his PhD at Berkeley in 1976, then joined Bell Laboratories in 1978, where he spent the most productive decade of his research life.

At Bell Labs in the mid-1980s, Chu's group built the first optical molasses: six laser beams, tuned just below an atomic resonance, arranged so that a sodium atom moving in any direction sees the light it approaches Doppler-shifted into resonance and is preferentially slowed. The atoms behaved as though immersed in a viscous fluid made of light, and cooled to around 240 microkelvin. In 1986 he added the optical dipole trap — the 'optical tweezers' — holding the cold atoms in place with a focused beam, a technique that later escaped physics entirely and became a standard tool in biology for manipulating single cells and molecules.

Chu moved to Stanford in 1987 and to a joint Berkeley/Lawrence Berkeley National Laboratory position, later directing the national laboratory. He shared the 1997 Nobel Prize in Physics with Claude Cohen-Tannoudji and William Phillips for the development of methods to cool and trap atoms with laser light. The cold atoms their techniques produced became the raw material for Bose–Einstein condensation, atomic fountain clocks, and atom interferometry.

In 2009 he became US Secretary of Energy under President Obama — the first working scientist and the first Nobel laureate to hold a US cabinet post — serving until 2013 and pushing hard on renewable energy and efficiency. He famously took personal charge of the technical response to the Deepwater Horizon blowout in 2010, including insisting on gamma-ray imaging of the failed blowout preventer. He returned to Stanford afterwards and has continued to work on both biophysics and climate.