Spin-dynamics of a quantum wave-packet via helical edge states and spin-filter effect

Topological insulator is a new class of material that is insulating in its bulk and metallic on its boundary due to the presence of helical boundary states within the energy gap of bulk modes. Considering an interface between a conductor and a topological insulator, there appears hybridization between bulk modes of the conductor and helical boundary modes of the topological insulator. It is expected that the hybridization leads to a non-trivial spin-dynamics of a quantum state at the interface and this effect suggests a new way of electronic spin-control. In this work, by means of an effective two-dimensional model of the interface and a unitary algorithm, we numerically investigate the spin-dynamics of a quantum wave-packet via the hybridization, and also examine the spin-filter effect through the helical edge channels.