Breaking and resurgence of symmetry in the non-Hermitian Su-Schrieffer-Heeger model in photonic waveguides

Abstract

Symmetry is one of the cornerstones of modern physics and has profound implications in different areas. In symmetry-protected topological systems, symmetries are responsible for protecting surface states, which are at the heart of the fascinating properties exhibited by these materials. When the symmetry protecting the edge mode is broken, the topological phase becomes trivial. By engineering losses that break the symmetry protecting a topological Hermitian phase, we show that a new genuinely non-Hermitian symmetry emerges, which protects and selects one of the boundary modes: the topological monomode. Moreover, the topology of the non-Hermitian system can be characterized by an effective Hermitian Hamiltonian in a higher dimension. To corroborate the theory, we experimentally investigated the non-Hermitian 1D and 2D SSH models using photonic lattices and observed dynamically generated monomodes in both cases. We classify the systems in terms of the (non-Hermitian) symmetries that are present and calculate the corresponding topological invariants.

24 pages, 17 figures

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Cited by in corpus (10)

• Exact Solutions Disentangle Higher-Order Topology in 2D Non-Hermitian Lattices
• Topological phases of commensurate or incommensurate non-Hermitian Su-Schrieffer-Heeger lattices
• Thermodynamics and entanglement entropy of the non-Hermitian SSH model
• Inverse Design of Winding Tuple for Non-Hermitian Topological Edge Modes
• A non-Hermitian Su-Schrieffer-Heeger model with the energy levels of free parafermions
• Topological Phases in Non-Hermitian Nonlinear-Eigenvalue Systems
• Thermodynamics of analogue black holes in a non-Hermitian tight-binding model
• Supercharging exceptional points: Full-spectrum pairwise coalescence in non-Hermitian systems
• Emergence of Imaginary Time Crystals in the non-Hermitian Su-Schrieffer-Heeger model
• Non-Hermitian Effects in the Su-Schrieffer-Heeger model: Exploring Substrate Coupling and Decoupling Dynamics