PHYSICS COLLOQUIUM

California State University, Long Beach
Monday, October 2, 2017 11:15am in PH1-223
(Refreshments served at 10:45am in HSCI-224)

Topological Order in Condensed Matter Physics
Prof. Michael R. Peterson
California State University Long Beach

In Landau’s theory of phase transitions, different phases of matter are understood and classified in terms of symmetry that can be locally probed. Since the early 1980’s new of phases of matter called topological phases have been discovered with the integer and fractional quantum Hall effects serving as the paradigmatic examples. Much of theoretical and experimental condensed matter physics has dedicated itself to the full understanding and classification of these newly discovered topological phases—the 2016 Physics Nobel prize in physics was awarded for “for theoretical discoveries of topological phase transitions and topological phases of matter” to David Thouless, Duncan Haldane, and Michael Kosterlitz. As the name would suggest, topological phases are gapped phases that possess topological, or global, order that cannot be classified by a local symmetry. Additionally, they are characterized by particle fractionalization (so-called anyons with fractionally charged quasi-particle excitations and fractional braiding statistics) and particular ground state degeneracies. Fascinatingly, a special kind of anyon called a non-abelian anyon has potential applications in the construction of a fault-tolerant (topological) quantum computer. I will discuss the reality of so-called intrinsic topological phases in the fractional quantum Hall effect and frustrated spin systems where the strongly interacting constituents produce emergent topologically ordered phases.