Topology and edge modes surviving criticality in non-Hermitian Floquet systems

• URL: http://arxiv.org/abs/2602.12588v1
• Date: Fri, 13 Feb 2026 04:01:55 GMT
• Title: Topology and edge modes surviving criticality in non-Hermitian Floquet systems
• Authors: Longwen Zhou,
• Abstract summary: We reveal gapless symmetry-protected topological phases (gSPTs) in systems tuned out-of-equilibrium by periodic drivings and non-Hermitian couplings.<n>Our findings identify gSPTs in driven open systems and uncover robust topological edge modes at phase transitions beyond equilibrium.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The discovery of critical points that can host quantized nonlocal order parameters and degenerate edge modes relocate the study of symmetry-protected topological phases (SPTs) to gapless regions. In this letter, we reveal gapless SPTs (gSPTs) in systems tuned out-of-equilibrium by periodic drivings and non-Hermitian couplings. Focusing on one-dimensional models with sublattice symmetry, we introduce winding numbers by applying the Cauchy's argument principle to generalized Brillouin zone (GBZ), yielding unified topological characterizations and bulk-edge correspondence in both gapped phases and at gapless critical points. The theory is demonstrated in a broad class of Floquet bipartite lattices, unveiling unique topological criticality of non-Hermitian Floquet origin. Our findings identify gSPTs in driven open systems and uncover robust topological edge modes at phase transitions beyond equilibrium.

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