Majorana states in a spin or qubit chain with a resonantly modulated coupling*

We show that a spin or qubit chain with the qubit coupling modulated close to twice the qubit frequency maps on the Kitaev chain. This is an example of topologically nontrivial Floquet dynamics induced in a trivial system by a simple sinusoidal modulation. The nontrivial regime exists in the frequency range with a width determined by the strength of the qubit coupling. Preparation of the system in this regime involves going through a quantum phase transition where the excitation gap closes, in the limit of an infinite chain. The results are compared with a quantum phase transition induced by a resonant parametric modulation of a system of coupled nonlinear mesoscopic oscillators, which remains topologically trivial [1].
1. M. I. Dykman, Christoph Bruder, Niels Lorch, and Yaxing Zhang, Phys. Rev. B 98 , 195444 (2018)