Hi,

Coming week's seminar talk will be given by Oliver Bürschaper, a visitor of Matthias Christandl:

Tuesday, Oct. 2, 16:30 in HIT J 52 on Hoenggerberg.

Best regards,

Stefan

___________________________________________________________________________

Title: Electric-magnetic duality and topological order on the lattice

Abstract: Dualities have had a profound impact in the history of physics and continue to serve as deep conceptual tools. In particular, electric- magnetic duality has a long tradition ranging all the way back to Dirac's idea of introducing magnetic monopoles to balance the asymmetry found in Maxwell's equations. Here we investigate the duality between electric and magnetic quasiparticle charges in spin systems with topological order, a new kind of collective order also appearing in the fractional quantum Hall effect. We define electric-magnetic duality for all of Kitaev's quantum double models based on groups and show that its natural habitat consists of a new class of topological models based on Hopf algebras. We interpret these as extended string-net models whose electric and magnetic projections give rise to the familiar string-net models by Levin and Wen, i.e. lattice realizations of all topological orders with parity and time-reversal invariance. Quite surprisingly, our electric- magnetic duality also yields tensor network states which are able to detect the topological structure of the surface underlying the model."

___________________________________________________________________________