Detecting Chern numbers in the time-of-flight images of superconducting multi-component systems

by Dr Ville Lahtinen (NORDITA)

Wednesday 21 Aug 2013, 14:00 → 15:00 Europe/Stockholm

A5:1069

The Chern number is a definitive theoretical signature for characterizing topological phases in two dimensions. Here we show that it can be faithfully detected as a winding number through a set of time-of-flight measurements, making it a diagnostic tool also in actual cold-atom experiments. We will show that the Chern number can be decomposed in terms of pseudospin winding numbers, which enables the scheme to be readily applied also to multi-component systems. To demonstrate this we apply our measurement scheme to a chiral topological model of spinless fermions that is adiabatically connected to Kitaev’s honeycomb lattice model. We show that phases characterized by Chern number ν = ±1, where vortices bind Majorana fermions, and by ν = ±2 that emerge as the unique collective state of such vortices, are reliably identified in the presence of realistic experimental perturbations.

Reference:
Phys. Rev. A 88, 013622 (2013).