# CMT Seminar: The fractional quantum Hall effect at filling 5/2: are non-abelians real?

Monday, November 9, 2009 - 3:15pm - 4:30pm

Reiss 261A

Michael R. Peterson

University of Maryland, College Park

One of the most important discoveries in physics in the past 25 years is the fractional quantum Hall effect (FQHE): a many-body strongly interacting system exhibiting the emergence of topological quasiparticles with fractional charged excitations and statistics and, perhaps, even non-Abelian quasiparticles for the FQHE in the second orbital Landau level at even-denominator filling factor 5/2. The 5/2 FQHE is currently motivating scientists partly due to its potential role in topological quantum computation and the fact that it still is mysterious after nearly 20 years. In this talk, I discuss the actual physical reality of the proposed topological non-Abelian Moore-Read Pfaffian description of the 5/2 FQHE. Specifically, theoretically it is found that the quasi-two-dimensional nature of the experimental FQHE systems, i.e., the finite width, produces a physical environment sufficient to stabilize the Moore-Read Pfaffian state (based on exact diagonalization using the spherical and torus geometries). Our results suggest the possibility of creating optimal experimental systems for the 5/2 FQHE state which are more likely to be described by the Pfaffian ansatz. I also mention the possibility of using FQHE bilayer systems to further shed light on the physical reality of the Pfaffian and the possibility of a quantum phase transition between abelian and non-abelian phases of matter. I acknowledge support from Microsoft Project Q and this work is done in collaboration with Sankar Das Sarma and Thierry Jolicoeur.

Host: Marcos Rigol