Anthony Leggett is a physicist who has made pioneering contributions to our theoretical understanding of superfluids — matter that behaves like a fluid without viscosity at very low temperatures — and, in particular, of superfluid liquid helium. Anthony confirmed the unexpected existence of superfluidity in the light isotope of helium, helium-3, by explaining another research group’s unusual results.
Already observed in the abundant helium-4 isotope, Anthony established that superfluidity in 3He occurs at even lower temperatures. This is because helium-3, unlike helium-4, must pair with itself — in a similar manner to the electron pairing that facilitates superconductivity — in order for superfluidity to occur, something only possible at extremely low temperatures. The breakthrough resulted in him being jointly awarded the 2003 Nobel Prize in Physics.
Anthony has received many other honours in recognition of his insightful work. These include his election as a Foreign Associate of the US National Academy of Sciences in 1997 and the 2003 Wolf Foundation Prize for his research into condensed matter physics. He received a knighthood for his services to physics in 2004.
Jointly with Alexei A. Abrikosov and Vitaly L. Ginzburg for pioneering contributions to the theory of superconductors and superfluids.
In the field of physics for key insights into the broad range of condensed matter physics.