Non-Hermitian Floquet phases with even-integer topological invariants in a periodically quenched two-leg ladder

Abstract

Periodically driven non-Hermitian systems could possess exotic nonequilibrium phases with unique topological, dynamical and transport properties. In this work, we introduce an experimentally realizable two-leg ladder model subjecting to both time-periodic quenches and non-Hermitian effects, which belongs to an extended CII symmetry class. Due to the interplay between drivings and nonreciprocity, rich non-Hermitian Floquet topological phases emerge in the system, with each of them been characterized by a pair of even-integer topological invariants $(w_0,w_{\pi })\in 2\mathbb{Z}\times 2\mathbb{Z}$. Under the open boundary condition, these invariants further predict the number of zero- and $\pi$-quasienergy modes localized around the edges of the system. We finally construct a generalized version of the mean chiral displacement, which could be employed as a dynamical probe to the topological invariants of non-Hermitian Floquet phases in the CII symmetry class. Our work thus introduces a new type of non-Hermitian Floquet topological matter, and further reveals the richness of topology and dynamics in driven open systems.

See https://www.mdpi.com/1099-4300/22/7/746 for the published version in the special issue of Entropy: Quantum Dynamics with Non-Hermitian Hamiltonians (Open Access)

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Cited by in corpus (1)

• Floquet engineering of topological localization transitions and mobility edges in one-dimensional non-Hermitian quasicrystals