Lev Landau was the head of the Theoretical Division at the Institute for Physical Problems from 1937 until 1962. Landau was arrested on 27 April 1938, because he had compared the Stalinist dictatorship with that of Hitler, and was held in the NKVD’s Lubyanka prison until his release on 29 April 1939, after the head of the institute Pyotr Kapitsa, an experimental low-temperature physicist, wrote a letter to Joseph Stalin, personally vouching for Landau’s behavior, and threatening to quit the institute if Landau were not released. After his release Landau discovered how to explain Kapitsa’s superfluidity using sound waves, or phonons, and a new excitation called a roton. Lev Landau led a team of mathematicians supporting Soviet atomic and hydrogen bomb development. Landau calculated the dynamics of the first Soviet thermonuclear bomb, including predicting the yield. For this work he received the Stalin Prize in 1949 and 1953, and was awarded the title “Hero of Socialist Labour” in 1954. His students included Lev Pitaevskii, Alexei Abrikosov, Evgeny Lifshitz, Lev Gor’kov, Isaak Khalatnikov, Roald Sagdeev and Isaak Pomeranchuk. Lev Landau’s 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 2.17 K (−270.98 °C).”

In 1937 Lev Landau married a woman from Kharkov, Kora T. Drobanzeva; their son Igor was born in 1946. Landau believed in “free love” rather than monogamy, and encouraged his wife and his students to practise “free love”; his wife was not enthusiastic. During his life, Landau was admitted involuntarily six times to the Kashchenko psychiatric hospital. He was an atheist. In 1957 a lengthy report to the CPSU Central Committee by the KGB recorded Landau’s views on the 1956 Hungarian Uprising, Lenin, and what he termed “red fascism”. Lev Landau died on 1 April 1968, aged 60, from complications of the injuries sustained in the car accident he was involved in six years earlier. He was buried at the Novodevichy cemetery.