Floquet Topological Superfluid and Majorana Zero Modes in Two-Dimensional Periodically Driven Fermi Systems

TL;DR

This paper demonstrates how periodic modulation of optical lattice potentials can induce topological superfluid phases with Majorana zero modes in two-dimensional Fermi systems, revealing novel Floquet topological phenomena.

Contribution

It introduces a simple method to realize Floquet topological superfluids and verifies the anomalous bulk-boundary correspondence in these driven systems.

Findings

Periodic driving induces topological phase transitions.

Robust chiral Floquet edge states can exist with zero bulk winding number.

Existence of Floquet Majorana zero modes at topological defects.

Abstract

We propose a simple approach to realize two-dimensional Floquet topological superfluid by periodically tuning the depth of square optical lattice potentials. We show that the periodic driving can induce topological phase transitions between trivial superfluid and Floquet topological superfluid. For this systems we verify the anomalous bulk-boundary correspondence, namely that the robust chiral Floquet edge states can appear even when the winding number of all the bulk Floquet bands is zero. We establish the existence of two Floquet Majorana zero modes separated in the quasienergy space, with $\varepsilon_{0,\pi}=0,\pi/T$ at the topological defects.