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.
Dr. 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, Dr. 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.
Dr. 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.
Dr. 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 Dr. 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 Görlitz, 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.
At the start of World War II, he volunteered for an antiaircraft unit rather than be drafted. His battery was sent to relieve German troops at Stalingrad but escaped encirclement by the Red Army.
Later, serving on the Western Front, he was captured in the Battle of the Bulge and spent a year in an American POW camp in France. After his release in 1946, he supported himself by fixing and trading radios and studied physics at Göttingen.
He received a doctorate at Göttingen in 1950 and pursued postdoctoral research at Duke University in North Carolina. He joined the University of Washington as an assistant professor in 1955 and became a full professor in 1961. He retired in 2002.
His first marriage, to the former Irmgard Lassow, ended in divorce, and their son, Gerd, died in 2013. Survivors include his wife, Diana Dundore; a grandson; and a great-granddaughter.
Dr. Dehmelt was elected to the American Academy of Arts and Sciences and the National Academy of Sciences. He received the National Medal of Science from President Bill Clinton in 1995.
Dr. Dehmelt had been dating Dundore when he got the early-morning call from Stockholm in 1989 informing him of his Nobel win.
Instead of mentioning the award, he asked her to marry him. They had earlier spoken, in a lighthearted way, that he would propose if he won the prize.
According to the University of Washington, Dundore described the call as “his way of delivering the news.” The university said they married soon after.
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