Zitterbewegung and bulk-edge Landau-Zener tunneling in topological insulators

Abstract

We investigate the ballistic Zitterbewegung dynamics and the Landau-Zener tunneling between edge and bulk states of wave packets in two-dimensional topological insulators. In bulk, we use the Ehrenfest theorem to show that an external in-plane electric field not only drifts the packet longitudinally, but also induces a transverse finite side-jump for both trivial and topological regimes. For finite ribbons of width \(W\), we show that the Landau-Zener tunneling between bulk and edge states vanishes for large \(W\) as their electric field-induced coupling decays with \(W^{-3/2}\). This is demonstrated by expanding the time-dependent Schr\"odinger equation in terms of Houston states. Hence we cannot picture the quantum spin Hall states as arising from the Zitterbewegung bulk trajectories `leaking' into the edge states as proposed in Phys. Rev. B 87, 161115 (2013).