Xiao-Gang Wen

Who is Xiao-Gang Wen?

Xiao-Gang Wen is a Chinese-born American physicist. He is a Cecil and Ida Green Professor of Physics at the Massachusetts Institute of Technology. His expertise is in condensed matter theory in strongly correlated electronic systems.

He is the author of a well-known book in advanced quantum many-body theory entitled, Quantum Field Theory of Many-body Systems: From the Origin of Sound to an Origin of Light and Electrons.

Wen studied superstring theory under theoretical physicist Edward Witten at Princeton University where he received his Ph.D. degree in 1987. He later switched his research field to condensed matter physics while working with theoretical physicists Robert Schrieffer, Frank Wilczek, Anthony Zee in Institute for Theoretical Physics, UC Santa Barbara.

Wen introduced the notion of topological order and quantum order, to describe a new class of matter states. This opens up a new research direction in condensed matter physics. He found that states with topological order contain non-trivial boundary excitations and developed chiral Luttinger theory for the boundary states. The boundary states can become ideal conduction channel which may leads to device application of topological phases. He proposed the simplest topological order — Z2 topological order, which turns out to be the topological order in the toric code. He also proposed a special class of topological order: non-Abelian quantum Hall states. They contain emergent particles with non-Abelian statistics which generalizes the well known Bose and Fermi statistics. Non-Abelian particles may allow us to perform fault tolerant quantum computations. With Levin, he found that string-net condensations can give rise to a large class of topological orders. In particular, string-net condensation provides a unified origin of photons, electrons, and other elementary particles. It unifies two fundamental phenomena: gauge interactions and Fermi statistics. He pointed out that topological order is nothing but the pattern of long range entanglements. This led to a notion of symmetry protected topological order and its description by group cohomology of the symmetry group. The notion of SPT order generalizes the notion of topological insulator to interacting cases. He also proposed the SU gauge theory of high temperature superconductors.