Dehmelt, Hans G (1923– )

German-born US physicist who was awarded the Nobel Prize for Physics in 1989 for his contribution to the development and application of the ion trap technique, used to store single atoms long enough to make accurate spectroscopic measurement on them. He shared the award with Norman Ramsey and Wolfgang Paul.

Dehmelt used the ion trap technique mainly for studying electrons and in 1973 he succeeded in observing a single electron in an ion trap, and holding the electron in the trap for months at a time. It proved possible to measure the magnetic moment of the trapped electron accurately to 12 digits, one of the most accurate measurements of a physical quantity ever made. Dehmelt was also able to trap and study single ions (charged atoms), pointing the way to improved atomic clocks.

Dehmelt was born and educated in Berlin, Germany. He studied physics at the University of Göttingen, attending classes held by Wolfgang Paul. After gaining his doctorate in 1949, he was invited to study at the microwave laboratory at Duke University, North Carolina, USA. He later moved to the University of Washington, Washington State, USA, demonstrating in 1956 the usefulness of ion trapping for high accuracy spectroscopy.