Leon Armenovich Takhtajan (Armenian: Լևոն Թախտաջյան; Russian: Леон Арменович Тахтаджян, born 1 October 1950, Yerevan) is a Russian (and formerly Soviet) mathematical physicist of Armenian descent, currently a professor of mathematics at the Stony Brook University, Stony Brook, NY, and a leading researcher at the Euler International Mathematical Institute, Saint Petersburg, Russia.
Takhtajan received in 1975 his Ph.D. (Russian candidate degree) from the Steklov Institute (Leningrad Department) under Ludvig Faddeev with thesis Complete Integrability of the Equation
Together with Ludvig Faddeev and Evgeny Sklyanin he formulated the algebraic Bethe ansatz and quantum inverse scattering method.
Together with Ludvig Faddeev and Nicolai Reshetikhin he proposed a method of quantization of Lie groups and algebras, the FRT construction.
[1][citation needed] In 1983 he was an invited speaker at the International Congress of Mathematicians in Warsaw and gave a talk titled Integrable models in classical and quantum field theory.