John George Valatin

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John George Valatin (Hungarian: Valatin János Györgi, 1918–19 April 1978) was a Hungarian-born British theoretical physicist and professor at Queen Mary University of London. He is best known for the Bogoliubov–Valatin transformation in many-body quantum theory.

Born in Budapest, he studied engineering at the Technical University of Budapest and earned a doctorate for work on molecular spectra. After a period in industry, he returned to academia after World War II as a lecturer. In 1947 he worked with Louis de Broglie at the Institut Henri Poincaré in Paris and earned a Doctor of Science from the University of Paris for his dissertation on the theory of the positron. In 1950 he moved to the Niels Bohr Institute in Copenhagen, where he worked on a covariant, gauge-independent formulation of quantum electrodynamics.

In 1952 Valatin joined the University of Birmingham, where he spent about 13 years with Rudolf Peierls and Paul Taunton Matthews. There he learned to use Feynman diagrams in quantum field theory and worked on regularization methods for divergences in QED. During this period he became a British citizen. He also worked with contemporary superconductivity theorists and, later, with John Bardeen, Leon Cooper and John Schrieffer.

Valatin independently developed the Bogoliubov–Valatin transformations in 1957, describing how particles pair up in quantum systems. He also generalized the Hartree–Fock method for superconductors. With Ben Roy Mottelson and David Thouless, he extended Hartree–Fock to include pairing forces in nuclear physics, giving the Thouless–Valatin self-consistent cranking model. With Carlo Di Castro, a PhD student, he studied phase transitions in superconducting thin films.

In 1965 Valatin was appointed to a chair at Queen Mary College, London, where he founded a theoretical physics group working in both particle and condensed matter physics. He had two sons with his wife and was known as a devout Christian.