Johannes Sjöstrand (born 1947) is a Swedish mathematician, specializing in partial differential equations and functional analysis.
Sjöstrand received his doctorate in 1972 from Lund University under Lars Hörmander.
He is a member of the Royal Swedish Academy of Sciences[2] and, since 2017, a member of the American Academy of Arts and Sciences.
His research deals with microlocal analysis.
He has investigated, inter alia, the Schrödinger equation of an electron in a magnetic field (with a spectrum of the Hofstadter butterfly),[3] resonances in the semiclassical limit, and quantum tunneling in the semiclassical limit.