Lev Davidovich Landau (Russian:Ле́в Дави́дович Ланда́у;IPA: [lʲɛv dɐˈvidəvʲitɕ lɐnˈda.u]; January 22 [O.S. January 9] 1908 –1 April 1968) was a Soviet physicist who made fundamental contributions to many areas of theoretical physics. His accomplishments include the independent co-discovery of the density matrix method in quantum mechanics (alongside John von Neumann), the quantum mechanical theory of diamagnetism, the theory of superfluidity, the theory of second-order phase transitions, the Ginzburg–Landau theory of superconductivity, the theory of Fermi liquid, the explanation of Landau damping in plasma physics, the Landau pole in quantum electrodynamics, the two-component theory of neutrinos, and Landau's equations for S matrix singularities. He received the 1962 Nobel Prize in Physics for his development of a mathematical theory of superfluidity that accounts for the properties of liquid helium II at a temperature below 7000217000000000000♠2.17 K (7000216999999999995♠−270.98 °C).