CPM Seminar

Topological transport out of equilibrium

Tami Pereg-Barnea

Department of Physics
McGill University

A Floquet topological insulator is the out-of-equilibrium analogue of a topological insulator. As such it exhibits edge states in its quasi-energy spectrum. However, these Floquet states are not stationary and are not populated according to some known equilibrium distribution. It is therefore interesting to ask whether the edge states are topologically protected and whether the conductivity is quantized.

In our work we find that while the one dimensional edge modes are robust against scattering, their conductivity is generally lower than the e²/h per edge. We explain this result using an intuitive picture of side bands which is made rigorous through the Floquet-Landauer formalism. Moreover, this picture is useful in interpreting time resolved ARPES experiments on periodically driven Dirac systems.