Born on 4 February 1927 to a Jewish family in Stuttgart, Germany, Rolf Landauer was a pioneer in the physics of information processing. As a boy, he immigrated to the US with his family in 1938 to escape Nazi persecution. Landauer attended Harvard University, earning his BA in 1945. After a brief stint in the US Navy, Landauer returned to Harvard, finishing his PhD in physics in 1950. In 1952 Landauer joined the research staff at IBM, where he would remain for the rest of his career. His early work focused on such topics as ferroelectric materials and semiconductors. By 1957 he had devised a formula that expresses the electrical conductance of a system in terms of scattering, for which he was later awarded the American Physical Society’s Oliver E. Buckley Condensed Matter Physics Prize. In 1962 Landauer became director of IBM’s solid-state sciences department. Among other things, he developed a semiconductor injection laser and investigated metal–oxide semiconductor technology. In 1965 he became assistant director of research. It was during Landauer’s management tenure during the 1960s that IBM’s research division became one of the most important and influential labs in the world. He decided to return to research and made important contributions in many areas, including conduction, the physics of computing, energy dissipation in logical operations, and the traversal time for a particle tunneling through a barrier. In 1961 he famously demonstrated that erasing a bit of information requires a thermodynamic cost, while writing information does not. Landauer’s principle demonstrated the concept that information is physical, and it was central to solving the paradox of Maxwell’s demon. In addition to the Buckley prize, Landauer won numerous other awards and was elected to the National Academy of Sciences and the National Academy of Engineering. He died of cancer in 1999 at age 72. (Photo credit: AIP Emilio Segrè Visual Archives, Physics Today Collection)
