Tsui, Daniel Chee (1939– )

Chinese-born US physicist who with US physicist Robert B Laughlin and German physicist Horst L Störmer was awarded the Nobel Prize for Physics in 1998 for the discovery that the application of an extremely powerful magnetic field on electrons can cause them to form a quantum fluid in which individual fractions of the electron's charge can be identified.

In 1982 Tsui and Störmer had been studying the integer Quantum Hall-Effect for which German physicist Klaus von Klitzing received the Nobel Prize for Physics in 1985. In their experiments, they used lower temperatures and applied a higher magnetic field than von Klitzing and they discovered a new integer step in the Hall resistance not previously reported. More significantly they discovered a series of new steps at non-integer sites. They called this observation the Fractional Quantum Hall effect but could not explain their findings. Robert B Laughlin explained their observation as the formation of quasiparticles, which then condensed together to form a new type of quantum liquid, similar to what had been reported for liquid helium. The electrons combined with the ‘flux quanta’ of the magnetic field to form these quasiparticles which were later called bosons. Quantum fluids are of great interest to scientists, who can apply results obtained from these liquids directly to the behaviour of subatomic particles.

Tsui was born in Henan province, China, and became a US citizen. He received his PhD in physics from the University of Chicago, USA, in 1967 and then joined Bell laboratories, Murray Hill, New Jersey, where he carried out his Nobel prize-winning research in 1982. He has been a professor at the department of electrical engineering at Princeton University, New Jersey, since 1982.