Today we celebrate Leo Esaki, on his 101th birthday. He was born on this day in 1925 in Osaka, Japan. While working in the Sony Corporation research laboratory in Japan, Esaki used some deceptively simple experiments to prove the existence of a new kind of tunneling phenomenon in a semiconductor. His discovery also showed that this effect could be used technically in so-called tunnel diodes. Esaki’s discovery opened up a new field of research and initiated intensive and successful developments at many international research laboratories. Esaki was awarded the 1973 Nobel Prize in Physics jointly with Ivar Giaever for their experimental discoveries regarding tunneling phenomena in semiconductors and superconductors, respectively. Watch our 2004 interview: