Leon Neil Cooper
1930–2024, New York City, USA, Providence, Rhode Island, USA
American physicist who discovered that electrons in a superconductor bind into Cooper pairs, the key to the BCS theory of superconductivity.
Trained at Columbia, Cooper joined John Bardeen's group at Illinois in 1955 to attack the puzzle of superconductivity. His 1956 demonstration that the Fermi sea is unstable to arbitrarily weak electron pairing — the Cooper pair — supplied the missing ingredient; with Bardeen and Schrieffer he completed the BCS theory the following year. At Brown he later worked on neural networks and cognitive science.
Nobel-winning work
Cooper shared the 1972 Nobel Prize for the BCS theory of superconductivity. His essential contribution was the 1956 'Cooper problem': two electrons above a filled Fermi sea, attracting through phonon exchange, always form a bound state, however weak the attraction.
This instability of the Fermi sea toward pairing explained why superconductors have an energy gap and condense into a macroscopic quantum state. The pairing concept has since spread to nuclear matter, neutron stars, ultracold atomic gases and even models of quark matter.
Workplaces: Brown University, University of Illinois at Urbana-Champaign
United States