During undergraduate study in 1929 at Kyoto Imperial University he majored in physics. He was engaged in graduate work for three years at the same university and was then appointed a research associate by Dr. Yoshio Nishina at the Institute of Physical and Chemical Research, Tokyo, where he started to work in a newly developed frontier of theoretical physics-quantum electrodynamics under the guidance of Dr. Nishina.
In 1937, Tomonaga went to Leipzig to study under and work with Heisenberg. He stayed there for two years and used the results obtained while working there to write up a thesis for the Tokyo University. He received his D.Sc. from Tokyo Imperial University and in 1941 he was appointed professor at the Tokyo University of Science and Literature.
Later, he was invited by Robert Oppenheimer, the leader of the Manhattan project to spend some time at the Institute for Advanced Study in Princeton. He studied a many-body problem on the collective oscillations of a quantum-mechanical system.
He received the Nobel Prize in Physics in 1965, jointly with Richard Feynman and Julian Schwinger, for their fundamental work in quantum electrodynamics, with deep –ploughing consequences for the physics of elementary particles.
He worked in Tokyo, Japan, in Leipzig, Germany in Tsukuba, Japan and at IAS (Institute for Advanced Study) Princeton, NJ. His paper on the photoelectric pair creation is well-known.
Sin-Itiro Tomonaga (March 31, 1906 – July 8, 1979)