(1922–    ), German-American physicist and Nobel laureate. Born in Goerlitz, he interrupted his studies at the University of Göttingen for World War II, was captured at the Battle of the Bulge, and spent a year as a prisoner of war in an American camp in France. In 1946, he resumed his studies at Göttingen, where he received his Ph.D. in 1950. He was a researcher there (1950–52) before assuming a similar position at Duke University in 1952; three years later he began teaching at the University of Washington in Seattle, and became a full professor in 1961. In that year he also became a U.S. citizen.

Dehmelt's graduate work in NUCLEAR MAGNETIC RESONANCE (q.v.) continued throughout his postgraduate years. He experimented with polarized atoms as they changed magnetic orientation, changes called quantum transitions (see QUANTUM THEORY,). To produce the polarized atoms, he developed an ATOMIC TRAP, (q.v.) to hold a beam of polarized electrons, and in 1959 he developed his first version of a Penning trap for electrons, using a specially shaped electric field and a magnetic field to confine particles; in 1973 he was able to trap a single electron. He continued his research until he was able to measure the gyromagnetic ratio of the electron to an accuracy of four parts in a trillion. Dehmelt and his collaborators managed to trap and observe a single electron for almost a year.

For “contributions of importance for the development of atomic precision spectroscopy,” Dehmelt and the German physicist Wolfgang Paul were jointly awarded one half of the 1989 Nobel Prize in physics; the American physicist Norman Foster Ramsey, Jr., was the recipient of the other half of the prize for “the invention of the separated oscillatory fields method and its use in the hydrogen maser and other atomic clocks.”