University of Illinois at Urbana-Champaign
|TITLE:||"Majorana fermions in a spin-ladder system"|
|DATE:||Monday, January 23, 2012|
|PLACE:||Building 223 / S-105|
ABSTRACT: I will present recent work on a two-legged spin-chain version of Kitaev's honeycomb model. Like its parent, this model maps to a p-wave superconductor with a topological phase hosting Majorana fermions. The spin system exhibits Z2 vortices which control the sign of a local chemical potential in the fermionic language. I will show that the existence of Majorana fermions can be inferred from a new topological invariant based on a transfer matrix approach. Interestingly, different vortex patterns lead to a diverse set of topological phase diagrams. The results of this work suggest that periodic potentials may be used to `tune' the topology of a 1D superconducting system -- an observation relevant to current proposals to realize Majorana fermions in quantum wires. Our approach offers insight into general features of the topological phase diagram of 1D p-wave superconductors including those with disorder.