Photo from the Nobel Foundation archive.
Born: 28 February 1948, St. Louis, MO, USA
Affiliation at the time of the award: Stanford University, Stanford, CA, USA
Prize motivation: "for development of methods to cool and trap atoms with laser light."
Prize share: 1/3
Stephen Chu was born in St. Louis, Missouri, into an academic family of Chinese heritage. He excelled at school and as a child liked to build models before becoming interested in chemistry experiments. He studied physics at the University of Rochester and continued his studies at UC Berkeley. There he began with theoretical physics until he realized that experimental physics was his calling. After Berkeley he did his Nobel Prize-winning work at Bell Labs. Chu served as United States Secretary of Energy from 2009 to 2013. He is married to physicist Jean Fetter, and the couple has two sons, Geoffrey and Michael.
At room temperature atoms and molecules in the air move about at breakneck speed. In order for them to be studied, they need to be slowed down or chilled. During the 1980s Steven Chu, Claude Cohen-Tannoudji, and William Phillips developed different methods for this. When atoms come in contact with light particles with fixed energies, photons, their movement is affected as if they had been bumped. With the aid of laser light from different directions and adjustment of the photon's energy for Doppler effects, the atoms can be cooled to extremely low temperatures and captured in a trap.