Physicist who won Nobel Prize for trapping single electrons
Sept. 9, 1922 - March 7, 2017
Hans G. Dehmelt, a German army veteran who served at Stalingrad and in the Battle of the Bulge during World War II, studied physics in his postwar civilian life and won the Nobel Prize for making possible the trapping of single electrons, died March 7 in Seattle. He was 94.
The University of Washington in Seattle, where he had been on the faculty for much of his career, announced the death, but did not provide a cause.
Probably none of the particles that compose the atom is as well known or as prominent in the devices of daily life as the electron. Great streams of electrons flow as electric currents through the wiring of computers, calculators and all sorts of communications equipment. They are everywhere and impossible to escape or do without.
Mr. Dehmelt’s major scientific contribution was developing a technique for isolating a single electron, pinning it down, fixing it in a place where its properties could be carefully studied without interference from the environment.
The technique he devised in the 1950s used electrical and magnetic fields to seize and hold individual electrons. The technique is also used for trapping other charged particles or ions. The electron is a negatively charged particle and as such responds to electrical and magnetic forces.
For his work, Mr. Dehmelt shared half of the 1989 Nobel Prize in physics with Wolfgang Paul of the University of Bonn in Germany, who worked in the same area. The other half went to Norman Ramsey of Harvard University.
Mr. Dehmelt’s efforts helped make possible the study of important properties of electrons, not in vast numbers, but on the level of individual carriers of electrical charge.
Atomic properties depend on the laws of quantum mechanics that permit only fixed, or quantized, energy levels. Electromagnetic radiation is emitted or absorbed in transitions among these levels.
More precise information about these levels and this radiation is obtainable if the sample involved can be reduced in size to a single particle, and if that particle can be studied over a sufficient duration.
Trapping individual electrons makes it possible to gain more precise knowledge of their properties as infinitesimally small magnets. It also has applications to quantum computing.
Mr. Dehmelt traced his years of work on electron trapping to a moment of inspiration that came while attending a lecture as a student at the University of Göttingen in Germany. With a piece of chalk, a professor made a dot on a blackboard and called it an electron.
Under quantum theory, the position of an electron could not be so simply fixed, but at that moment in Göttingen, the idea of trying to do so entered Mr. Dehmelt’s mind. It prompted him to study, calculate and control electron orbits in electric and magnetic fields until, as he said in an autobiographical sketch, “the isolation of a single electron became a reality in 1973.” This work was followed in the 1980s by isolation of an ion of magnesium.
Hans Georg Dehmelt was born in Gorlitz, Germany, on Sept. 9, 1922. An early fascination with radios sparked his interest in science. As a boy, his do-it-yourself projects so engrossed him, he wrote, that only tutoring from his father kept him from a disastrous performance in school.