Hans Georg Dehmelt is a German-born American physicist, who was awarded Nobel Prize in Physics in 1989, for co-developing the ion trap technique with Wolfgang Paul, for which they shared one-half of the prize. Their technique was used for high precision measurement of the electron g-factor. He was born on September 9, 1922 in Gorlitz, Germany. Dehmelt’s Penning trap, which he developed in 1955, can confine electrons and ions in a small space for long periods of time in relative isolation. In 1973 Dehmelt used his device to isolate a single electron for observation, an unprecedented feat that opened the way for the precise measurement of key properties of electrons. Dehmelt and his colleagues went on to develop methods for measuring atomic frequencies and individual quantum jumps (the transitions between atomic energy levels) with unprecedented precision. In the 1970s Dehmelt used his trap to measure an electron’s magnetic moment to an accuracy of four parts in a trillion, the most precise measurement of that quantity at the time. He was awarded the National Medal of Science in 1995.