Hans Georg Dehmelt
1922–2017, Görlitz, Germany, Seattle, Washington, USA
German-born American physicist who shared the 1989 Nobel Prize in Physics for developing the Penning ion trap and measuring the electron's magnetic moment with record precision.
Born in Görlitz, Germany, Dehmelt served in the German army in WWII before completing his PhD at Göttingen in 1950. In 1955 he moved to the University of Washington in Seattle, where he perfected the Penning trap — a combination of electrostatic quadrupole and uniform magnetic fields holding single charged particles in a high vacuum. In 1973 his group stored a single electron for months and used the 'geonium' configuration (1976) to measure the electron's anomalous magnetic moment to about one part in 10¹², the most precise test of quantum electrodynamics at the time.
Nobel-winning work
Dehmelt's share of the prize recognized the realization of spectroscopy on individual trapped particles. His Penning-trap 'geonium atom' — a single electron bound to an ion in a Penning trap — allowed continuous Stern–Gerlach-type observation of quantum jumps and yielded the electron magnetic-moment anomaly a = 0.001159652188(4), matching QED to extraordinary accuracy.
The same trapping techniques underpin today's ion clocks, mass spectrometry of single particles and trapped-ion quantum computing.
Workplaces: University of Washington
United States, Germany