Prof. Walker obtained his Ph.D. in physics from Princeton University in 1988, then spent two years at JILA before establishing his laboratory at the University of Wisconsin-Madison in 1990, where he is currently Professor of Physics. He is the recipient of an Alfred P. Sloan Research Fellowship, a David and Lucile Packard Foundation Fellowship, a National Science Foundation Young Investigator Award, and was selected as an "Outstanding Referee" by the American Physical Society in 2009. At the University of Wisconsin he has been named an H. I. Romnes Fellow and a Vilas Associate. He is a 1999 Fellow of the American Physical Society, "For pioneering research in spin exchange, optical pumping, ultracold collisions, spin polarized beams and targets, laser cooling, and electron scattering." He has supervised the research training of more than thirty students and scientists at levels ranging from high-school to post-doctoral.
Prof. Walker prepares and studies novel states of matter using lasers. In his laboratory, he and his students use lasers to cool atoms to microKelvin temperatures, and they study the interactions between atoms at these extremely low temperatures. They use lasers to produce spin-polarized atoms at temperatures ranging from microKelvins to hundreds of Kelvin, with applications to spin-polarized nuclei (used for magnetic resonance imaging, for example) and fetal biomagnetism.