Emergent Phenomena in Flat Worlds

Date

Jan 24, 2013

Time

4:40 PM - 5:40 PM

Speaker

Dr. Kai P. Schmidt

Affiliation

TU Dortmund

Language

en

Main Topic

Physik

Other Topics

Physik

Host

Prof. Dr. M. Vojta

Description

Emergent Phenomena in Flat Worlds Kai P. Schmidt (TU Dortmund) Correlated quantum systems in two dimensions display a variety of fascinating properties. One of the most intriguing issues is the concept of topological order which goes beyond the paradigm of classifying the ground states of nature by spontaneous symmetry breaking. Most interestingly, topologically-ordered quantum systems possess elementary excitations with fractional quantum numbers and unconventional particle statistics. One of the standard models displaying topological order is the so-called toric code wich is an exactly solvable model of interacting spins. In this talk we investigate the stability of the topological phase of the toric code model in the presence of a uniform magnetic field by means of variational and high-order series expansion approaches. We find that when this perturbation is strong enough, the system undergoes a topological phase transition whose first- or second-order nature depends on the field orientation. When this transition is of second order, it is in the Ising universality class except for a special line on which multi-criticality is expected.

Last modified: Jan 21, 2013, 4:53:33 PM