| Abstract: |
| We present results on the interplay between nonlinearity, nonreciprocity, and topology in non-Hermitian lattices. We demonstrate that nonreciprocal topological lattices support insensitive edge states whose spectral properties remain immune to symmetry-breaking nonlinear perturbations, due to a competition between nonlinear self-interactions and mode nonorthogonality. We then analyze bulk wave-packet dynamics in the nonlinear Hatano-Nelson model, identifying three successive regimes driven by nonreciprocal amplification, and derive analytical predictions showing that nonlinearity modifies both the magnitude and time dependence of wave-packet acceleration. Finally, we show that nonlinearity enables unidirectional soliton formation in active nonreciprocal lattices, demonstrated analytically and experimentally in an active electrical transmission line. |
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