David James Thouless
1934–2019, Bearsden, Scotland, Cambridge, England
British-American theoretical physicist who brought topology into condensed matter — co-inventor of the Kosterlitz–Thouless transition.
Thouless studied at Cambridge under Hans Bethe then taught at Birmingham and Washington. With Michael Kosterlitz he showed (1972–73) that in two dimensions phase transitions can occur without 'symmetry breaking', through unbinding of vortex–antivortex pairs. He was also part of the TKNN group quantizing the Hall effect via topological Chern numbers.
Nobel-winning work
The Kosterlitz–Thouless transition explains superfluidity, superconductivity and magnetism in two-dimensional films: at low temperature vortex–antivortex pairs stay bound; above a threshold they unbind and destroy long-range order. This topological idea — with the TKNN formula for the quantum Hall effect — redefined states of matter via global geometric invariants.
Workplaces: University of Washington, University of Birmingham
United Kingdom, United States