General Physics Colloquium

'Fractional quantum Hall physics and topology in lattice systems'

Anne E. Nielsen

MPI-Quantenoptik, Garching, Germany

The discovery of the fractional quantum Hall effect in the early  eighties revealed the physical existence of phases of matter that  differ fundamentally from previously known phases, and these phases  are still under intense investigations today. The property that makes  them special is that they are topological. Topology is the study of  quantities that do not change when a geometrical object is deformed  smoothly. Examples include the twist of a Möbius strip and the hole  through a torus.

One way that topology can appear in two-dimensional quantum many-body  systems is through the existence of anyons. Anyons are localized  excitations that look like particles, but nevertheless have  properties that normal, isolated particles cannot have. Anyons are  interesting from a fundamental point of view and also for, e.g.,  quantum computation.

In recent years, there has been a lot of effort towards clarifying  under which conditions the fractional quantum Hall effect can occur.

One motivation for this is the hope to find easier and more robust  ways to realize the effect experimentally.

In this talk, I will first give an introduction to topology and the  fractional quantum Hall effect. I will then discuss some recent  proposals for engineering fractional quantum Hall physics under new  conditions.

Wine and cheese will be served at 4 PM